US20030173293A1 - Method for subsurface aerated treatment of wastewater - Google Patents
Method for subsurface aerated treatment of wastewater Download PDFInfo
- Publication number
- US20030173293A1 US20030173293A1 US10/292,185 US29218502A US2003173293A1 US 20030173293 A1 US20030173293 A1 US 20030173293A1 US 29218502 A US29218502 A US 29218502A US 2003173293 A1 US2003173293 A1 US 2003173293A1
- Authority
- US
- United States
- Prior art keywords
- wastewater
- air
- influence zone
- soil
- flow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000002351 wastewater Substances 0.000 title claims abstract description 176
- 238000000034 method Methods 0.000 title claims description 33
- 239000002689 soil Substances 0.000 claims abstract description 110
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 58
- 230000000694 effects Effects 0.000 claims abstract description 25
- 239000000203 mixture Substances 0.000 claims abstract description 22
- 238000004065 wastewater treatment Methods 0.000 claims abstract description 6
- 230000003716 rejuvenation Effects 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims description 54
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 45
- 239000001301 oxygen Substances 0.000 claims description 45
- 229910052760 oxygen Inorganic materials 0.000 claims description 45
- 239000011800 void material Substances 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 10
- 239000010865 sewage Substances 0.000 claims description 3
- 238000002386 leaching Methods 0.000 abstract description 27
- 239000004575 stone Substances 0.000 abstract description 25
- 230000008859 change Effects 0.000 abstract description 16
- 229920006395 saturated elastomer Polymers 0.000 abstract description 9
- 238000009826 distribution Methods 0.000 description 26
- 239000000470 constituent Substances 0.000 description 12
- 238000012545 processing Methods 0.000 description 12
- 239000000126 substance Substances 0.000 description 11
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 10
- 239000012528 membrane Substances 0.000 description 10
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 10
- 230000008569 process Effects 0.000 description 10
- 238000001764 infiltration Methods 0.000 description 9
- 230000008595 infiltration Effects 0.000 description 9
- 230000035699 permeability Effects 0.000 description 8
- 239000007787 solid Substances 0.000 description 7
- 238000006467 substitution reaction Methods 0.000 description 7
- 238000011144 upstream manufacturing Methods 0.000 description 7
- 241000894006 Bacteria Species 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 239000001569 carbon dioxide Substances 0.000 description 5
- 229910002092 carbon dioxide Inorganic materials 0.000 description 5
- 238000013461 design Methods 0.000 description 5
- 239000010410 layer Substances 0.000 description 5
- 230000003068 static effect Effects 0.000 description 5
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 4
- 239000003673 groundwater Substances 0.000 description 4
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 238000009434 installation Methods 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 239000000523 sample Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 230000012010 growth Effects 0.000 description 3
- 230000033001 locomotion Effects 0.000 description 3
- 238000009428 plumbing Methods 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 239000004576 sand Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 239000002680 soil gas Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 102000004190 Enzymes Human genes 0.000 description 1
- 108090000790 Enzymes Proteins 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical group [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- DOIMTEFBXJGEHS-UHFFFAOYSA-N O=[O+][O-].C Chemical compound O=[O+][O-].C DOIMTEFBXJGEHS-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 241000700605 Viruses Species 0.000 description 1
- KFVPJMZRRXCXAO-UHFFFAOYSA-N [He].[O] Chemical compound [He].[O] KFVPJMZRRXCXAO-UHFFFAOYSA-N 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- 230000002547 anomalous effect Effects 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 244000052616 bacterial pathogen Species 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000009412 basement excavation Methods 0.000 description 1
- 230000003115 biocidal effect Effects 0.000 description 1
- 230000004071 biological effect Effects 0.000 description 1
- 230000031018 biological processes and functions Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000009530 blood pressure measurement Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000003610 charcoal Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 239000010840 domestic wastewater Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 238000005206 flow analysis Methods 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000004519 grease Substances 0.000 description 1
- 239000010800 human waste Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000003973 irrigation Methods 0.000 description 1
- 230000002262 irrigation Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004060 metabolic process Effects 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000002991 molded plastic Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000005445 natural material Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910017464 nitrogen compound Inorganic materials 0.000 description 1
- 150000002830 nitrogen compounds Chemical class 0.000 description 1
- 239000012044 organic layer Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 238000005325 percolation Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000000344 soap Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/74—Treatment of water, waste water, or sewage by oxidation with air
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/28—Anaerobic digestion processes
- C02F3/2866—Particular arrangements for anaerobic reactors
- C02F3/288—Particular arrangements for anaerobic reactors comprising septic tanks combined with a filter
-
- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03F—SEWERS; CESSPOOLS
- E03F1/00—Methods, systems, or installations for draining-off sewage or storm water
- E03F1/002—Methods, systems, or installations for draining-off sewage or storm water with disposal into the ground, e.g. via dry wells
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/727—Treatment of water, waste water, or sewage by oxidation using pure oxygen or oxygen rich gas
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/78—Treatment of water, waste water, or sewage by oxidation with ozone
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/03—Pressure
Definitions
- the present invention relates to the subsurface disposal of wastewater (sewage); in particular, to disposal of wastewater by means of cesspools, septic tank type systems and associated leach fields.
- Subsurface wastewater disposal systems are widely used for on-site processing of wastewater from dwellings and other smaller volume wastewater sources.
- wastewater is delivered via a wastewater line to a septic tank for primary processing.
- the septic tank effluent, or wastewater is flowed to a leaching system for secondary processing by means of distribution pipes.
- the leaching system also commonly called a disposal field, leach field, or infiltration field, typically comprises permeable soil of the earth and some sort of excavation in the soil which is filled with stone particulate such as crushed stone or coarse gravel (typically 2.5 cm in dimension) and or a mechanical component, the function of which is to convey wastewater through a conduit, to infiltrate it into the soil.
- the principal function of the septic tank is to effect primary wastewater processing by engendering physical separation and retention of solids which are lighter and heavier than water, typically by settling and baffling. Solids, which settle out as sludge, are mostly decomposed by action of bacteria in a typically anaerobic environment. Gases, which are generated in the process, are vented to atmosphere.
- the wastewater from the septic tank is typically conveyed to the leach field by passing it through a distribution box and piping which channels wastewater to the leach field trenches, in a predetermined fashion.
- the wastewater is supposed to be free of solids of significant size. It will contain suspended solids of fine size, microorganisms such as bacterium and viruses, and various chemical constituents.
- the purpose of the leach field is generally to cause the wastewater to be treated or renovated, so it can be benignly returned to the hydrologic cycle that characterizes the movement of water into, through, and from soil beneath the surface of the earth.
- What follows is a simplified version of certain conventional ways of looking at leach field operation phenomena, to provide a conceptual framework for appreciating the invention. It is not intended to be comprehensive nor limiting.
- a traditional leach field is comprised of a trench filled with small (2-3 cm) stone pieces.
- a perforated pipe runs through the stone, delivering the wastewater along the trench.
- a popular modern type of leach field comprises a series of interconnected arch shaped molded plastic chambers having perforated walls, such as leaching chambers sold under the Infiltrator brand name. See U.S. Pat. No. 5,401,116 of J. Nichols, and U.S. Pat. No. 5,511,903 of J. Nichols et al.
- Infiltrator® chambers are directly buried in a trench in substitution of the stone-and-pipe leaching device.
- the leach field must have sufficient capacity to receive and properly process the anticipated flow of wastewater.
- the steady state capacity, or the infiltration rate, of a leach field is a function of the resistance to wastewater flow of the surfaces of the trench and the surrounding soil, as such may be influenced by hydraulic phenomena other than permeability, such as capillary action. For illustration here, only the sidewall of the trench will be now discussed. If distilled water is processed in sterile soil of a leach field, the infiltration rate is purely a function of the mechanics and hydraulics of the soil. However, in that wastewater contains organic substances, over time, an active, stable, moist biological crust layer frequently grows on surfaces. Of particular interest is the crust layer which occurs on a trench sidewall and within the nearby soil, especially when the layer tends to block openings in leaching system conduits.
- the crust also commonly called a biomat or biocrust
- the biomat is an organic layer, typically 0.5-3 cm thick. It is normally less permeable than the surrounding soil.
- the biomat often significantly determines the long-term steady state infiltration capacity of a leach field.
- the biomat also serves as a filter for bacteria and some suspended solids. In a properly functioning system, the surrounding soil to remain desirably unsaturated and aerobic, thus enabling antibiotic attack of any pathogenic bacteria, and more importantly, chemical reactions involving free oxygen. Biomat is thought to aid in filtering things which enter the influence zone.
- Foreign constituents in the wastewater may also sorb and or react with soil constituents; or they may ultimately be only diluted upon return to the ground water.
- the typical best remedy for such is to replace or extend the leach field. Failure can also be manifested by an inability of a given system to handle normal peak loads of wastewater which were handled in the past, and by inadequate purification of the wastewater in the influence zone, resulting in pollution of the groundwater. And, even if a system has not failed, it is desirable to guard against failure by having the greatest economically feasible margin of safety against failure.
- Cesspools favored in some regions, avoid the use of septic tanks. Untreated wastewater from a source is dumped into and partially treated by natural processes in the pool of an underground pit, and, the the wastewater infiltrates into the influence zone of soil surrounding the pit for futher treatment. Phenomena and problems similar to those described for leach fields will exist in cesspool influence zones.
- An object of the invention is to provide means for improving the function of septic tank type disposal systems and leach fields, to remedy failures, or forestall failure, or improve performance, in ways that are economical and practical.
- a further object of the invention is to effect desirable biochemical and physical conditions within the influence zone of a leach field.
- a still further object is to provide a way of sustaining or rejuvenating leach field performance while at the same time enabling continuous use of a septic tank type wastewater system.
- a significant pressure differential with atmospheric pressure is created, as gas, comprised of air or other biochemically active gas, flows between the conduit and the influence zone, in an amount effective for physical and or chemical change within the zone.
- gas comprised of air or other biochemically active gas
- the flow of active gas is sufficient in amount to make the composition of gas within the influence zone effectively different from the composition which exists therewithin, in the absence of such flowing.
- air flows from a conduit, into and through the influence zone, in the same direction as the wastewater flows. In another embodiment, air flows from the influence zone and into the conduit. In both embodiments, an air mover such as a blower or vacuum pump establishes a significant pressure differential in the influence zone.
- an air mover such as a blower or vacuum pump establishes a significant pressure differential in the influence zone.
- a blower pressurizes the system conduits relative to atmosphere, and air flows through the influence zone, the adjacent soil, and ultimately back to atmosphere. If the influence zone is saturated, the pressure of air causes the water in the influence zone to physically move away from the conduit and the zone is de-saturated. When not fully saturated, the pressure of air flow causes physical gas exchange, to make the composition of gas in the influence zone more near that of atmosphere.
- air flows similarly, but from an unpressurized conduit to an auxiliary pipe which is buried in the soil and maintained at below atmospheric pressure.
- and air mover lowers the pressure of gas in the conduit and air flows from atmosphere, through the soil and influence zone and into the conduit.
- air is introduced into the bottom of the leaching trench by a pipe diffuser or by pipes which run lengthwise within the trench.
- the differential air pressure between the conduit and atmosphere is at least 2.5 mm, preferably about 7.5 cm or more, water column, in order to produce a desired level of biochemically significant flow through the influence zone.
- the pressure in the soil of the influence zone when, in preferred embodiments, air is flowed from a conduit into the influence zone, the pressure in the soil of the influence zone, about 15 cm from the inner boundary of the influence zone, will be at least about 0.03 mm water column, more preferably at least 0.8 mm.
- the influence zone of a deteriorated system is substantially anaerobic in character, and flowing of air or active gas causes the change so that it becomes predominantly aerobic.
- the quantity of air or other gas which is flowed into the influence zone provides oxygen substantially in excess of the stoichiometric quantity which is required for oxidation of the oxidizable constituents in the wastewater, as such constituents are typically determined by measurement of Oxygen Demand, in particular Biological Oxygen Demand (BOD).
- BOD Biological Oxygen Demand
- a gas or liquid substance is added to the air to enhance biochemical activity.
- the auxiliary pipe is buried under the trench or is within the trench.
- a membrane is optionally placed within or on the soil, to control the direction in which air travels from or to the soil surface.
- the air flow of the invention may be maintained continuously or intermittently, with and without simultaneous flow of wastewater in a preferred practice of the invention, by means of a control system. To ensure good functioning of a system, a low volume of air is continuously flowed into the wastewater system and the air moves through the influence zone contemporaneously with wastewater.
- apparatus for treating wastewater is comprised of a primary unit, such as a septic tank or other kind of reactor for primary processing of the wastewater, a leach field, for receiving wastewater effluent of the primary unit, where the leach field is comprised of a trench in the soil, a conduit within the trench, and soil adjacent the trench comprising an influence zone, and a means, such as a blower or vacuum pump, for producing a pressure differential between the conduit and the adjacent soil, where the pressure differential is significant enough to effect a physical change, such as forcing water from the influence zone soil, or to effect biochemically significant change in the biochemistry of the influence zone.
- a primary unit such as a septic tank or other kind of reactor for primary processing of the wastewater
- a leach field for receiving wastewater effluent of the primary unit
- the leach field is comprised of a trench in the soil, a conduit within the trench, and soil adjacent the trench comprising an influence zone
- a means such as a blower or vacuum pump
- a means such as a mechanical check valve or a water trap, in the pipeline of the wastewater system, so the effect of applied pressure or vacuum is limited to localized parts of the wastewater system.
- a check valve in the distribution pipe, which runs from a septic tank or the like to a distribution box, or other distribution piping, and air pressure is injected at one or more selected points in the distribution piping or conduits.
- pressure or vacuum is applied to the wastewater line running into the septic tank and a check or other valve is present upstream of the point of connection to the wastewater line of the blower or vacuum pump source of differential pressure.
- a blower is in the stack vent of the system.
- Use of the valve means enables use of the system for processing wastewater simultaneously with use of air flow.
- a check valve bypass line, temporary storage reservoir and pump are optionally in the wastewater line to further aid in the objective of continuous use.
- the duration or periods during which air is flowed is optionally controlled by a control system which senses the composition or pressure of gas or liquid in vicinity of the influence zone or elsewhere in the wastewater system.
- the apparatus is configured so that there is a void space above the soil surface of the influence zone, through which wastewater flows downwardly.
- the void might be the space within an arch shape chamber or the spaces amongst stones within a trench.
- the water is first flowed in sufficient quantity and rate until it accumulates as a pond above the soil surface.
- the air pressure is applied to the void, to give impetus to the natural flow of water.
- the application of air pressure is ceased, and either the water flow is resumed right away, or there is a period of quite time which is substantially longer than the time of applying air pressure.
- the cycle may be repeated continuously. The process saves energy by decreasing the duration of air mover operation.
- the amount of air or other gas provides a quantity of air per unit time of system operation which quanity is many times greater, e.g., 10 to 25 times or more, than the quantity which theoretically would satisfy the biological oxygen demand of the wastewater.
- the invention is effective in improving the operation of leach fields in a cost-effective way. Leach field performance and biochemistry are improved and maintained through use of the system.
- the invention can be applied to existing installations and new installations. It is quite useful for rejuvenating the function of a system which has been either under-designed or over-used.
- FIG. 1 is a perspective view of the basic elements of a prior art septic tank wastewater system, having a composite of leaching field trench types.
- FIG. 2 is a elevation cross section through the pipe and stone filled trench portion of the leach field of the system shown in FIG. 1.
- FIG. 3 is a elevation cross section through the arch shape leaching chamber-filled trench portion of the leach field of the system shown in FIG. 1.
- FIG. 4 is a semi-schematic, part-cross sectional, side elevation view of a septic tank type wastewater system having means for creating positive pressure gradient and outward air flow in the soil adjacent the leach field trench.
- FIG. 5 is a semi-schematic cross sectional end view of a portion of a leach field, analogous to the views of FIGS. 2 and 3, showing how pressure-vacuum auxiliary pipes are buried in the soil laterally adjacent the chamber-filled leach field trenches. It also schematically illustrates an associated control system.
- FIG. 6 is a view analogous to FIG. 5, showing one of a plurality of pipe and stone filled trenches having an underlying auxiliary vacuum pipe; together with a graph showing how negative pressure varies with depth within the soil and apparatus shown in the left of the Figure.
- FIG. 7 is a view analogous to FIG. 5, showing one of a plurality of chamber filled trenches with one of a multiplicity of spaced apart pressure-vacuum auxiliary vertical pipes adjacent the trench.
- FIG. 8 is a semi-schematic elevation view illustrating how a pressurized air line and a check valve are positioned in the wastewater line upstream of a septic tank through which air flows.
- FIG. 9 is a view like FIG. 8 showing a J-trap check valve used in substitution of the mechanical check valve shown in FIG. 8.
- FIG. 10 is a view like FIG. 8, showing a check valve in a bypass line for a valved wastewater line.
- FIG. 11 is a view like FIG. 10, showing a reservoir and pump for receiving and forcing wastewater downstream into the septic system while it is pressurized.
- FIG. 12 is a view like FIG. 10, showing a variation on the apparatus illustrated in FIG. 11.
- FIG. 13 is a fragmentary view like the view of FIG. 4, showing a blower positioned in the stack vent line.
- FIG. 14 is a view like FIG. 3, showing an oblong air distribution diffuser lightly buried in the soil beneath the bottom of a leaching chamber.
- FIG. 15 is a view like FIG. 2, showing two air distribution perforated pipes within the stone of the trench.
- FIG. 1 illustrates components of a typical septic tank wastewater system, familiar in the prior art. Wastewater flows through wastewater line 18 from a dwelling or other source to a septic tank 20 . Wastewater flows from tank 20 , through a distribution system. In particular, the wastewater flows through distribution pipeline 22 , to distribution box 30 ; and, then through further distribution pipes 56 to the leach field 40 .
- FIG. 1 shows a composite of two familiar types of leaching field construction.
- FIGS. 2 and 3 respectively show elevation cross section views through each of the two types.
- a trench 35 is filled with crushed or naturally small stones 36 typically about 2.5 cm in dimension, (hereafter referred to as “stone”); and, a perforated pipe 32 distributes wastewater along the trench.
- the wastewater issuing from the pipe 32 may be temporarily stored in the voids within the stone; and, as indicated by the arrows 54 , it then flows into the soil 38 (also called soil profile) beneath the surface 42 of the earth through the bottom and or side walls of the trench.
- a typical biomat 44 forms on and within the surface of the trench.
- Additional biomat will typically be present on the stones in the trench, and may be present to such an extent as to run like a membrane across stones which lie at the perforations or openings of the pipe. While typical, a biomat will not necessarily be present in a wastewater system.
- the trench is filled by a string of interconnected molded arch shaped plastic leaching chambers 34 , such as Infiltrator® chambers.
- a string of interconnected molded arch shaped plastic leaching chambers 34 such as Infiltrator® chambers.
- Wastewater flows into the hollow interior of the chamber from pipe 56 , where it may be stored temporarily, and it then flows into the soil, out the open bottom wall of the trench and through perforations in the sidewall, as indicated by arrows 54 .
- the chamber defines and maintains the trench, and provides the conduit means for distributing wastewater along the trench.
- a pipe which is a continuation of line 56 , runs along the length or a chamber interior peak to abet distribution of wastewater within a string of interconnected chambers.
- the side walls of trench 35 are defined by the chamber walls and the bottom is parallel to the base of the chamber.
- the trench is made larger than the chamber, and crushed stone surrounds the chamber.
- the infiltration rate into soil is often limited at least in part by the presence of one or more biomat layers. And, in both types there will be within the soil adjacent to the trench an influence zone 50 , having a nominal outer boundary 52 , where the wastewater is (or should be, in a properly functioning wastewater system) largely renovated, or biochemically converted into a more environmentally benign form, prior to re-introduction into the ground water.
- the geometric definition of the influence zone is somewhat arbitrary and it can vary in dimension with time, as will be appreciated from the discussion in the Background and herein.
- the outer boundary 52 is imaginary and not intended to represent any limiting dimension or proportion. While the invention is described in terms of soil of the earth, it will be understood that such term comprehends installations comprised in whole or part of artificial porous material such as sand and gravel and other particulate media.
- the distribution portion of the FIG. 1 system includes a typical distribution box 30 , which is intended to balance flow between the branches of the system.
- a typical distribution box 30 which is intended to balance flow between the branches of the system.
- the distribution box is omitted, and the invention will be understood as being applicable in obvious ways to such systems.
- chambers and stone-trench pipes, dry wells, galleries, and all other substitutional devices—whether surrounded with small stone or buried directly in soil, are all considered conduits of fluid, within a context that some serve other functions as well.
- cesspools and injection wells are also considered as comprising conduits and as functioning in part at least as leach fields.
- Cesspools are devices that function as both a primary unit and a leaching unit.
- raw sewage is introduced directly from the source, and as biochemical action takes place in the pool, the wastewater percolates into the surrounding soil.
- injection wells wastewater is pumped into the earth through a vertical pipe so it disperses into material beneath or around the pipe.
- leaching chambers Most of the rest of the description here uses the example of leaching chambers.
- FIG. 4 shows a semi-schematic side elevation view of a gravity flow septic tank system, which is an improvement on the essential system shown in FIG. 1.
- a wastewater line 18 runs downwardly from building 60 to septic tank 20 , for primary processing. Wastewater from an unshown sanitary appliance or other source is introduced into inlet end 62 of the wastewater line. Gases, which come up the wastewater line from the septic tank, are vented through stack vent 58 which protrudes above the building roof.
- baffles 66 prevent floating solids from moving out of the tank an into the first part of the distribution subsystem, effluent exit pipe 22 .
- the primarily treated wastewater flows from the septic tank, through check valve 70 , into distribution box 30 , and then into leach field 40 which is comprised of several parallel strings of leaching chambers 34 , one of which strings is shown.
- Blower 71 causes pressurized air, drawn through air inlet pipe 72 to flow down air pipeline 68 and into the distribution box.
- Check valve 74 protects the blower from back flow of wastewater and smelly gas when it is not in operation.
- An odor-absorbing charcoal filter may optionally be used with or without the check valve.
- the pressure of the air will desirably hasten the flow of water out of the influence zone. Some air may move directly upwardly from the trench interior to the surface. If the soil above the trench is saturated, as it may be in a severely failed leaching system, upward flow should be helpful in restoring the system. In experiments, it has been found that upward air flow is not a particular problem. In many systems, the soil tends to be compacted above the trench, which inhibits such flow. As discussed below, a barrier on or in the soil above a leach field trench will tend to inhibit upward flow.
- the air flow into the conduit is maintained for a desired time, according to the result sought and obtained. After a time, air flow may be ceased, so the system resumes its normal operation; or, the system may be used during the time of air flow, as described below.
- a low power centrifugal blower is sufficient for producing the pressure differential which induces flow through the soil.
- the means for providing pressurized air will depend on the resistance of the air flow path.
- a regenerative type blower is used if a relatively high pressure is needed.
- other means for flowing air may be used, such as blowers, fans, compressors, etc., according to the air moving performance required and the price of the component. Unless stated otherwise, all pressures stated herein are gage pressures, i.e., relative to atmosphere.
- Biomat is normally anaerobic. To the extent such is present, air flow will tend to make it at least temporarily aerobic, thus engendering desirably different biological or chemical reactions which alter and reduce the biomat.
- air is forced into the influence zone and beyond, along the same general flow paths which wastewater has.
- the influence zone and adjacent soil are saturated, there will be a physical/hydraulic effect, as forcing air into them will tend to unsaturate them.
- the influence zone is not appropriately aerobic, the flow of air tends to make it so, both by physical displacement and by desirable biochemical activity. If there is an accumulation of oxygen-demanding constituents within the influence zone and surrounding soil, they will be desirably oxidized and reduced in amount.
- the invention process maintains or improves, as the case may be, the function of a leach field by (a) a physical (mechanical, pneumatic, hydraulic) effect; and (b) a chemical and or biological effect, which for simplicity if referred herein to as a biochemical effect, or in related fashion, to a change in biochemistry.
- an aerobic soil is one which is macroscopically aerobic, e.g., the preponderance of the volume of the soil of interest has oxygen tension sufficient for sustaining predominantly aerobic bacterium.
- An anaerobic soil in this description is one which is not aerobic. Nonetheless, within a mass of aerobic soil, such as the influence zone, the environment may vary from point to point, and anaerobic conditions can exist within a predominantly aerobic environment. For example, anaerobic micro-pores may be present within an array of aerobic macro-pores.
- the gross environment in the influence zone can be looked at in another way, according to principles of stoichiometry.
- wastewater can be characterized according to Oxygen Demand.
- Oxygen Demand is a characterization of how much oxygen is needed to effectively treat the oxidizable constituents in the wastewater to make them environmentally benign.
- Oxygen Demand is usually divided into two constituents, namely Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD). COD is commonly measured by the so-called Hach Method 8000.
- BOD Biological Oxygen Demand
- COD Chemical Oxygen Demand
- Hach Method 8000 For wastewater systems associated with habitations, BOD is the commonly used parameter of interest. It is commonly measured in accord with United States Environmental Protection Agency Standard 405.1.
- Stoichiometry refers to the chemical balance between an oxidizable material and oxidizer, in this instance, within the influence zone. If the influence zone receives a quantity of air which is stoichiometric, it means the quantity is exactly that which is necessary for complete theoretical oxidization of the oxidizable matter in the zone. In real situations, there are imperfect mixing and other influences, and to achieve full oxidation, some excess air (oxygen) is required. Thus, from this viewpoint, the desired aerobic influence zone will be characterized by oxygen-bearing gas flow over time, e.g., hours, which is in substantial excess of stoichiometry for the oxidizable constituents of the wastewater entering the zone over the same time.
- the excess stoichiometric air flow can derive from artificial means, such as through use of the invention, by natural means such as migration through permeable soil, or by a combination of those.
- artificial means such as through use of the invention
- natural means such as migration through permeable soil, or by a combination of those.
- a continuous flow of 280 l/minute of injected air provides 50-100 times the stoichiometric quantity for a typical about 1200 l/day wastewater stream.
- air is characterized as an active gas. It maintains or alters the composition of constituents and biochemistry of the influence zone. It contains oxygen and enables oxidation. Accordingly, other active gases may be used with or in substitution of air. For instance, oxygen or ozone enriched air may be used for better activity, and an oxygen-helium mixture may be used for a combination of greater fluidity and activity.
- liquid or gaseous additives such as reactive substances like hydrogen peroxide, surfactants, and the like, may be introduced into the air stream in line 68 from additive system 76 , by pumping or other obvious means. See FIG. 4. Alternatively, they may be introduced separately into the leach field conduits at the distribution box, distribution pipes 56 , or chambers. Included within the effects of such additives will be to promote wetting, to act as solvents, and to increase oxidization or to promote other biochemical activity beyond what air induces.
- an influence zone will be saturated with water and the pressure and flow within the soil of the influence zone is sufficient to unsaturate it.
- an influence zone will initially have a composition that is deficient in oxygen, being biochemically significantly less than the volume percent oxygen in air, and it will be changed so it approximates the composition of air. For instance, a starting composition of 14-19% oxygen will be changed to 20-21%, at a point about 15 cm from the inner boundary of the influence zone.
- the influence zone and surrounding soil will have constituents, in addition to oxygen, which are substantially different from the composition of air. For instance, carbon dioxide may exceed 2%, methane 1% and hydrogen sulfide 0.005%. Use of the invention will change such values in the direction of the composition of air.
- the amount of gas which is flowed into the influence zone is biochemically effective.
- the air flow is sufficient in quantity to alter the biochemical conditions in the influence zone from those conditions which would exist in the absence of flowing, to a degree which is significant to the treatment of wastewater and soil.
- biochemical or biochemistry is described above.
- Another primary aspect of the invention is to physically move water from the influence zone and to replace it by air to a degree sufficient to create an aerobic region in part or all of the influence zone and or to increase the permeability of the zone. What is an effective amount can vary with the starting condition in the influence zone.
- an effective amount of gas will change the zone so that treatment of wastewater, which simultaneously or subsequently enters the zone, will be significantly better treated.
- the quantity of wastewater e.g., volume and oxygen demand
- the quality of the effluent from the influence zone will be higher in the context of common environmental standards for underground water, the permeability of the zone will be increased
- the pressure necessary to cause a unit of gas flow through the zone will drop
- the pressure gradient within the zone for a given flow of gas will drop, the zone will change in character from anaerobic to aerobic, the quantity of water resident in the zone at any given instant will decrease
- the fraction of oxygen in the zone will increase
- the fraction of gases associated with anaerobic activity such as carbon dioxide, methane and hydrogen sulfide
- the conduit static pressure will preferably be in the range 1-100 cm water column. Obviously, when a liquid is to be pushed from a saturated zone, the initial pressure required is higher than if there is no saturation. If there is saturation, and it is alleviated by air treatment, the necessary pressure drops. Likewise, when the biochemistry is changed, soil permeability tends to be increased, and the necessary pressure drops.
- Differential pressure may be applied for many hours, extending into days or continuous operation, to achieve the desired effects.
- it can be very difficult to detect flow and pressure gradients, the presence of which is inferred and implicit because there is a measurable change in the gas content of the soil during use of the invention, as shown by the example below.
- the efficacy of the invention is often best determined by desirable change in, or maintenance of, gas content of the soil.
- oxygen is made high; carbon dioxide, methane, hydrogen sulfide and nitrogen compounds are made or kept low; all in the direction of the content of atmospheric air or in a biochemical direction which is better than air for aerobic bacterium.
- the apparatus in FIG. 4 may be modified somewhat to make an alternate embodiment in which a vacuum, instead of pressure, is applied to the distribution box, distribution pipes or chambers of the leach field.
- Check valve 70 A is replaced by a manual or motorized valve. The valve is closed during vacuum operation—assuming the vacuum level is such that it would unacceptably draw the contents from the septic tank. Any liquid drawn toward the vacuum pump is appropriately trapped by common means, and the liquid is re-introduced into the wastewater line or septic tank.
- a vacuum is applied, air is drawn from the surface of the earth, through the soil, the influence zone, any biomat, and into the chamber, in ways which will be appreciated from the other description here.
- the air drawn from the system by the vacuum pump may be exhausted to atmosphere. Thus, there is serial flow which is the reverse of that which is described when the conduit is pressurized.
- the leaching system cannot be used for processing wastewater from the septic tank during the time it is placed under vacuum.
- one or more pressure-vacuum perforated pipes 72 are installed, either as original equipment or as retrofit, in proximity to, and parallel to, the chamber-filled trenches 35 . Air is either drawn from the pipes 72 or forced into the pipes 72 , so that the leach field is beneficially affected.
- pipes 72 are connected to a vacuum pump and gas is pulled from the soil. Appropriate common traps and trap emptying means are used to handle any wastewater that is drawn into the auxiliary pipes and to the pump, and the trapped water is recycled to the septic tank or leach field.
- the evacuation of pipes 72 pulls air from the chambers to the extent they are in communication with atmosphere by means of vents in the distribution box (e.g., in substitution of line 68 ) or chambers, or through the septic tank and stack vent 58 , consistent with other discussion herein.
- auxiliary pipes When auxiliary pipes are vented, air will be drawn from the earth surface 42 downwardly through the soil 38 , as indicated by arrows in the Figure, according to the vacuum level, the permeability of the soil and conditions inside the chambers. Preferably, there is significant flow through the chambers and trench walls, to replicate to a degree the effect achieved when the chambers are pressurized, as described above in connection with FIG. 4.
- auxiliary pipes 72 are placed sufficiently close to the trenches/chambers, and deep enough, to create a pressure gradient across the biomat if any and within the influence zone.
- a membrane such as plastic sheet 96 , is optionally placed in the soil profile above the pipes 72 to limit downward flow of air in between the chambers.
- the membrane When the chambers are not vented to enable air flow directly from atmosphere to the chamber interior, the membrane tends to cause the air to flow from surface 42 towards, into and through, the chambers.
- the membrane is a layer of relatively impermeable natural material, laid within the indigenous soil.
- the membrane is placed on the earth surface 42 .
- the membrane runs substantially horizontally; in other modes, the membrane may run vertically or at an angle with or without a horizontal membrane.
- the surface of the earth is compacted or otherwise treated to lessen permeability and to thereby functionally create a membrane.
- FIG. 6 shows a stone filled trench and pipe 72 , together with a coordinated graph showing the estimated nominal variation in pressure P versus depth from the surface.
- the pipe 72 is beneath and parallel to a stone filled trench 35 and evacuated.
- a sub-atmospheric pressure gradient is established along the arbitrary vertical reference line D, as indicated by the dashed line P on the right side of the Figure.
- the pressure gradient induces the air flow indicated by the arrows on the left side part of the Figure.
- the air flows through the soil above the trench, more freely through the spaces amongst the stones, and then vertically down through the soil beneath the trench, and into the pipe. Corresponding pressure gradients and flows will be inferred for chambers having evacuated auxiliary pipes directly below.
- auxiliary pipes 72 are pressurized to thus create a positive pressure gradient and related flow within the soil. This will be essentially the inverse of the phenomena just described for evacuated pipes.
- the pressure in the soil in vicinity of the trench, chamber, or pipe, as the case may be will be supra-atmospheric and air will flow into the pipe and upwardly through the soil profile to the chamber and or soil surface.
- pressure or upward air flow may also retard the downward flow and escape of wastewater to ground water, which could be either desirable or undesirable depending on reactions in the influence zone.
- FIG. 7 is a fragmentary picture which will be understood from its analogy to FIG. 5.
- FIG. 7 shows one of a plurality of spaced apart vertical pipes 78 , which is positioned adjacent one or more of the trenches, along the length of the trench, in place of the horizontal pipes 72 .
- the pipes 78 have perforated lower ends 79 , to enable air to flow into and from the soil.
- the flow of gases, according to whether the pipe is pressurized or evacuated is indicated by the double-headed arrows.
- Pipes 78 may alternatively be angled downwardly so the lower pipe ends are positioned beneath the trench, rather than adjacent to it as shown.
- vertical pipe will encompass pipes which are generally running in an upward direction, whether true vertical or at an angle to such, in which case they are only generally vertical.
- the advantage of the use of vertical injection or suction pipes is one of easy retrofit.
- Combinations of horizontal vertical (and angled) pipes and means for interconnecting them to the source of pressure or vacuum will present themselves.
- the horizontal or vertical aeration pipes shown in FIG. 5 or 7 , and the diffusers of FIGS. 14 and 15 discussed below, may be installed proximate or within individual trenches, or portions thereof, rather than generally throughout an entire leaching system, to cope with a localized problem.
- FIG. 5 The operation of the FIG. 5 embodiment, as well as operation of other embodiments of the invention, may be controlled as indicated by the schematic control diagram portion of FIG. 5.
- the composition and or pressure of gas in the influence zone or soil adjacent the zone is sensed using a gas sensor comprised of a probe 74 and an analyzer 76 .
- the analyzer provides a first signal to controller unit 94 which compares the first signal to a desired reference point (characteristic of a desired reference gas composition or pressure) and provides a second signal to the air mover 71 , to thereby modulate flow of air to or from pipe 68 and pipes 72 , according to the difference between the first signal and the reference point.
- the air flow may be modulated by stopping and starting the air mover, or by increasing or decreasing the pressure.
- the reference composition is selected in accord with the teachings herein.
- the reference composition may be such as 20% oxygen, or less than 1% carbon dioxide.
- the reference pressure is selected in relationship to other parameters which measure the performance of the influence zone, and based on accumulated experience with like wastewater systems.
- FIG. 14 is a view like FIG. 3, showing a chamber having a oblong cross section pipe 94 called here a diffuser, buried at shallow depth beneath the soil at the base of the chamber.
- Diffuser 94 may be alternatively laid on the soil at the base of the chamber.
- Diffuser 94 is connected to a source of pressurized air, so pressurized air is forced into the chamber in an evenly distributed way, to achieve the desired effect which has been described in connection with FIGS. 5 - 7 .
- FIG. 15 is like FIG. 14 and FIG. 3, showing a perforated wastewater pipe 32 in a stone filled trench 35 .
- Running along the length of the bottom of the trench are two small diameter auxiliary pipes 96 carrying pressurized air.
- the pipes 96 are shallowly placed in the soil 38 beneath the trench, in manner analogous to FIG. 14.
- FIG. 4 there is a further embodiment which is useful, when the leach field chambers are pressurized. It comprises using the characteristic of the septic tank outlet to provide the means which prevents the back flow of air toward the wastewater line 18 , instead of employing check valve 70 .
- the septic tank outlet is an elbow
- the head or water in the septic tank may resist back flow pressures of 2-100 cm water column.
- the septic tank outlet or inlet may be modified by blocking off the openings which permit air passage.
- FIG. 8 shows such a construction in semi-schematic fashion, comprising check valve 80 in wastewater line 18 .
- a check valve which is useful in this embodiment and others described is a common horizontal flap type check valve sold in connection with PVC wastewater pipe of 7.5-10 cm diameter. Manually or power actuated mechanical valves referred to herein are likewise commercially available.
- FIG. 9 The side elevation semi-schematic view of FIG. 9 shows another way for preventing back flow which can be used in substitution of a check valve, namely J-trap 82 .
- the trap type is familiar for toilets and other plumbing appliances. Sometimes, it is referred to as a U-trap.
- the J- or U-type of traps, and any other functional equivalent is referred to hereafter as a water trap.
- wastewater water is retained in the base of the J-shape contour of line 18 .
- the asymmetrical nature of the J shape means that there is more resistance to upstream flow of a fluid, compared to downstream flow.
- the J-trap is functions analogously to a check valve, in impeding flow of air and water in the downstream direction more than in the other direction.
- the back flow resistance can be overcome by raising the pressure sufficiently high, but so can a mechanical check valve be overcome by sufficiently high pressure.
- the depth of the J can be used to set the head to which the downstream part of the septic system can be subjected.
- the valve in the wastewater line functions to limit upstream movement and the valve may be a mechanical or water trap. It will be appreciated that in certain circumstances a water trap valve may be functionally sufficient and thus useful on the downstream side of the septic tank.
- FIG. 10 is a semi-schematic elevation view of a variation on FIG. 8.
- the primary wastewater line 18 is fitted with valve 80 A.
- Bypass wastewater line 86 with associated bypass check valve 82 , provides a bypass around the valve 80 A.
- Valve 80 A is kept open during periods when there is no air pressurization of the system, i.e., during use of the wastewater system as it takes place in absence of use of the invention.
- wastewater will not consequentially pass through the check valve. This eliminates possible noise that might be heard by occupants of the building, arising from operation of check valve 82 as wastewater passes through.
- FIG. 11 is a view like FIG. 10. It shows a plumbing arrangement which is useful when the pressure in the leach field, due to air flowing down feed pipe 68 , is more than the head of wastewater coming down the wastewater pipe can overcome.
- the valve 80 B in the main wastewater line 18 A is closed. This causes wastewater coming down the wastewater line 18 to accumulate in reservoir 84 .
- the pump 87 forces wastewater through line 86 and forces it into the septic tank.
- Check valve 82 B prevents any back flow when the pump is not operating.
- FIG. 12 is like FIG. 10 and shows still another plumbing variation.
- Flow to reservoir 84 along bypass line 86 is controlled by valve 82 C.
- valve 82 C When the valve 82 C is closed, wastewater flows along the main wastewater line through check valve 82 .
- the valve 82 C is opened, wastewater preferentially flows down line 86 into reservoir 84 from whence, according to signals from unshown sensors, the pump 87 C is activated to force wastewater down line 86 C to overcome the air pressure in the wastewater system.
- the apparatuses described in connection with FIGS. 10 - 12 may be alternatively installed in exit line 22 or distribution line 56 .
- FIG. 13 shows how a centrifugal type blower 71 can be placed in the stack vent line 58 , when J-trap 92 (or a functional substitute, e.g., a plurality of appliances having integral traps), or a mechanical valve (e.g., on-off or flap-check), is present to prevent back flow of pressurized air, up the wastewater line 18 into building 60 .
- J-trap 92 or a functional substitute, e.g., a plurality of appliances having integral traps
- a mechanical valve e.g., on-off or flap-check
- the blower forces air downwardly in the stack, and into the septic tank.
- the blower allows wastewater decomposition gases to escape up the stack.
- the blower may be placed at the upper end of the stack vent, exterior of the building.
- a kit of components which cooperate when installed, may be provided, e.g., to an installer of wastewater treatment system owner.
- the kit may comprise all or part of the following: a means for connecting an air flow supply to a wastewater or a distribution line, a flow checking means, an air mover, and a control system.
- the leach field conduits will not be vented to atmosphere along their lengths or at their ends farthest from the septic tank.
- the invention can be applied to such kinds of vented conduits.
- the air mover has to have capacity sufficient to achieve the necessary static pressure while accommodating the loss of air out the vent.
- the vents are fitted with valves.
- the conduits will be vented through the septic tank and stack vent.
- other vents into the conduits can have a positive or neutral effect.
- the air mover was a 93 w, 1700 l/minute blower.
- Soil gas composition was measured using a commercial gas analyzer and a probe which inhibits infiltration of surface air. See U.S. Pat. No. 6,018,909. Pressure was measured with the same kind of probe.
- the applied positive pressure at the wastewater line was continuous and ended at the time shown for the readings. It gradually declined as the flow increased with the passage of time. Wastewater use was continued during the test, with at an estimated 1200 l/day input.
- Readings S7S and S7D were taken in the influence zone, respectively at depths of 30 and 75 cm from the earth surface at the end of a 30 m first trench length. Reading S1S was taken at the inlet end of the same first trench.
- air may be applied continuously or discontinuously.
- the dynamics of the system will permit discontinuous air flow.
- water is flowed in alternation with the flow of air or other active gas.
- wastewater flow varies over the course of the day, and the time of flowing air may be varied in coordination with such.
- a blower may be run for one hour of presumed non-use, during the nighttime hours.
- a blower may be run for two equally spaced apart half hour periods each day.
- the time for airflow may be relatively small as a fraction of the total time of a wastewater flow day.
- a dosing pump or other means periodically delivers water to the leach field from a septic tank or other sump.
- the leach field is periodically dosed with wastewater, sufficient to create ponding, or a standing water level, on top of the soil of the influence zone.
- the inside of the conduit of FIG. 3 is supplied with water at a rate and quantity such that it accumulates within the chamber on the underlying influence zone.
- the trench of FIG. 2 is likewise supplied for a first period of time by flow through the perforated pipe, so that water accumulates to a certain level within the broken stone of the trench. When the pond is created, the flow of water is ceased. Then after some delay to allow natural percolation, or alternatively without delay, air pressure is applied to the conduit.
- the pressure is maintained for a certain second time period, which may be a matter of a quarter hour, or more or less.
- the air pressure time is sufficient to force the wastewater to flow through the influence zone downwardly and otherwise, and to cause air to flow into the influence zone.
- the air pressure is ceased and the system is allowed to remain quiet for a third period of time, which period of time is substantially greater, for example, two times or more greater, than the time during which air was flowed.
- the oxygen which is delivered by the airflow has a biochemically beneficial effect within the influence zone, as has been previously described.
- the third time period may be essentially zero. Monitoring of system performance and the character of water exiting the influence zone will help determine what the third time period should be.
- the cycle is repeated again with another dosing of wastewater, nominally like the first cycle.
- a sensor such as a float or other commercial liquid level sensor is installed in the void space.
- a signal from the sensor stops the inflow of water by the dosing pump, when the water reaches a predetermined level.
- the blower is energized by the control system, to apply the pressurized air.
- an oxygen sensor embedded in the influence zone is used to determine when air has sufficiently flowed into the influence zone, and to stop the flow of air.
- a timer determines when dosing is restarted. The timing and duration of dosing will obviously also be a function of the wastewater which is flowed into the system.
- air is provided in an amount which is greatly in excess of the calculated amount which would be theoretically necessary to satisfy the oxygen demand of the waste water.
- demand for a domestic dwelling will be primarily BOD.
- a system has a flow of about 1140 l/day (about 300 gal/day) and a BOD of about 150 mg/l, resulting in a calculated oxygen demand of about 0.17 kg/day.
- Air is flowed to the leach field at about 2.5 cm (1 inch) water column pressure and about 285 l/min (10 cubic feet per minute) for one hour per day, so that the total air flow is about 17,000 l.
- the weight flow of oxygen gas was about 26 times the weight of BOD in the waste water.
- the BOD of the wastewater exiting the influence zone is tested and found to be about 1 to 5 mg/l.
- a commercial establishment has a flow of about 1500 l/day (350-400 gal/day) of about 1000 mg/l BOD to a leach field.
- Air is supplied on a continuous basis at the rate of about 2850 l/min (100 cubic feet per minute).
- the input oxygen is about 1080 kg/day while the oxygen demand of the wastewater is about 2.6 kg/day.
- the flow of oxygen in the air is about 400 times the amount of oxygen demanded by the wastewater.
- the airflow per unit time provides at least several times the theoretical oxygen demand of wastewater per unit time.
- a unit of time that is convenient is a 24 hour day.
- the invention will be useful in wastewater systems which process wastewater streams from industrial, agricultural, food processing, commercial, etc., operations, which wastewater streams present the same disposal problems as domestic wastewater from habitations.
- the septic tank is a unit for primary processing or treatment of wastewater and the leach field provides secondary processing or treatment of the wastewater, as such terms are well understood in the art.
- Septic tanks are commonly known to comprise predominantly anaerobic environments.
- the invention will also be useful with leach fields which derive wastewater from other sources than primary units.
- Other devices, both aerobic and anaerobic may be substituted for septic tanks as the primary (treatment) unit. For instance, an aerobic reactor which agitates the wastewater with air may be used.
Abstract
The performance of a leach field of a septic tank type wastewater treatment system and other analogous devices is enhanced, maintained or rejuvenated by flowing air or other active gas through conduits of the system. Air is flowed serially through cesspools, leaching chambers, perforated pipes in stone filled trenches, leach pits and the like, and the adjacent soil where wastewater treatment takes place. In alternate embodiments, conduits are pressurized or evacuated; and, auxiliary pipes are buried in vicinity of the conduits. An air mover creates a differential pressure sufficient to effect a significant pressure differential with atmosphere and to effect a desired physical or biochemical change in the soil adjacent the conduits. A typical pressure will be around 7-8 cm (about 3 inch) water column. If the soil is saturated, the air pressure will push water from the soil, as well as change the gas composition in the soil. The flow of wastewater may be alternated with the flow of air. Different valve devices and piping configurations are used to manage the desired flow of air and wastewater.
Description
- This application is a continuation in part of patent application Ser. No. 09/526,381, filed Mar. 16, 2001, now U.S. Pat. No. ______, and claims benefit of Provisional Application Serial No. 60/125,070, filed Mar. 17, 1999.
- The present invention relates to the subsurface disposal of wastewater (sewage); in particular, to disposal of wastewater by means of cesspools, septic tank type systems and associated leach fields.
- Subsurface wastewater disposal systems, commonly called septic tank systems or septic systems, are widely used for on-site processing of wastewater from dwellings and other smaller volume wastewater sources. Typically, wastewater is delivered via a wastewater line to a septic tank for primary processing. The septic tank effluent, or wastewater, is flowed to a leaching system for secondary processing by means of distribution pipes. The leaching system, also commonly called a disposal field, leach field, or infiltration field, typically comprises permeable soil of the earth and some sort of excavation in the soil which is filled with stone particulate such as crushed stone or coarse gravel (typically 2.5 cm in dimension) and or a mechanical component, the function of which is to convey wastewater through a conduit, to infiltrate it into the soil.
- The principal function of the septic tank is to effect primary wastewater processing by engendering physical separation and retention of solids which are lighter and heavier than water, typically by settling and baffling. Solids, which settle out as sludge, are mostly decomposed by action of bacteria in a typically anaerobic environment. Gases, which are generated in the process, are vented to atmosphere. The wastewater from the septic tank is typically conveyed to the leach field by passing it through a distribution box and piping which channels wastewater to the leach field trenches, in a predetermined fashion. The wastewater is supposed to be free of solids of significant size. It will contain suspended solids of fine size, microorganisms such as bacterium and viruses, and various chemical constituents.
- The purpose of the leach field is generally to cause the wastewater to be treated or renovated, so it can be benignly returned to the hydrologic cycle that characterizes the movement of water into, through, and from soil beneath the surface of the earth. What follows is a simplified version of certain conventional ways of looking at leach field operation phenomena, to provide a conceptual framework for appreciating the invention. It is not intended to be comprehensive nor limiting.
- As the wastewater travels from within a leach trench and through the soil in a properly functioning system, it is subjected to natural chemical and biological processes within a “zone of influence”, which may extend 30-120 cm from the trench interface with the soil. A traditional leach field is comprised of a trench filled with small (2-3 cm) stone pieces. A perforated pipe runs through the stone, delivering the wastewater along the trench. A popular modern type of leach field comprises a series of interconnected arch shaped molded plastic chambers having perforated walls, such as leaching chambers sold under the Infiltrator brand name. See U.S. Pat. No. 5,401,116 of J. Nichols, and U.S. Pat. No. 5,511,903 of J. Nichols et al. Typically, Infiltrator® chambers are directly buried in a trench in substitution of the stone-and-pipe leaching device.
- The leach field must have sufficient capacity to receive and properly process the anticipated flow of wastewater. The steady state capacity, or the infiltration rate, of a leach field is a function of the resistance to wastewater flow of the surfaces of the trench and the surrounding soil, as such may be influenced by hydraulic phenomena other than permeability, such as capillary action. For illustration here, only the sidewall of the trench will be now discussed. If distilled water is processed in sterile soil of a leach field, the infiltration rate is purely a function of the mechanics and hydraulics of the soil. However, in that wastewater contains organic substances, over time, an active, stable, moist biological crust layer frequently grows on surfaces. Of particular interest is the crust layer which occurs on a trench sidewall and within the nearby soil, especially when the layer tends to block openings in leaching system conduits.
- The crust, also commonly called a biomat or biocrust, is an organic layer, typically 0.5-3 cm thick. It is normally less permeable than the surrounding soil. Thus, the biomat often significantly determines the long-term steady state infiltration capacity of a leach field. The biomat also serves as a filter for bacteria and some suspended solids. In a properly functioning system, the surrounding soil to remain desirably unsaturated and aerobic, thus enabling antibiotic attack of any pathogenic bacteria, and more importantly, chemical reactions involving free oxygen. Biomat is thought to aid in filtering things which enter the influence zone. Nitrogen, discharged in human waste, is characteristically passed through any biomat, predominantly as ammonium (NH4 +), to be nitrified, or converted to nitrate (NO3) form, in the aerobic environment of the influence zone and adjacent soil. Foreign constituents in the wastewater may also sorb and or react with soil constituents; or they may ultimately be only diluted upon return to the ground water. As the wastewater is renovated in the influence zone, it moves mostly outwardly and downwardly toward the ambient water table in the earth. Some water may move upwardly into the vadose above the trench, by capillarity, evaporative-uptake and plant-uptake. It is usually required that the bottom of the leach field trench be a particular distance above the ambient water table, because sub-optimal wastewater treatment conditions exist in the extremely moist soil, the capillary fringe, just above the water table.
- In a properly designed, used and maintained septic tank disposal system, once biochemical equilibrium is reached, the capacity of the leach field remains stable insofar as infiltration or leaching capacity. A long term infiltration rate, or liquid acceptance rate, characteristic soils of southern New England, USA is about 8-32 liters/m2/day. However, too frequently, a septic tank system will demonstrate insufficient infiltration capacity. Typically, a failure is manifested by escape of wastewater to the surface of the soil, or by a substantial backing up of wastewater in the wastewater line. One cause of failure can be gross flow of solids from the septic tank into the leach field piping or chamber system, and blockage of the perforations in such components. The typical best remedy for such is to replace or extend the leach field. Failure can also be manifested by an inability of a given system to handle normal peak loads of wastewater which were handled in the past, and by inadequate purification of the wastewater in the influence zone, resulting in pollution of the groundwater. And, even if a system has not failed, it is desirable to guard against failure by having the greatest economically feasible margin of safety against failure.
- Among the known causes of some failures are the following. The design of the system has become inadequate for the current conditions, either due to growth of a very heavy biomat, a changed character of wastewater, or changed conditions within the soil in the influence zone. For instance, the biological oxygen demand (BOD) of the wastewater may have been increased, or the ambient soil conditions changed, so that the desired biochemical conditions for stable aerobic function in the influence zone are no longer obtained. An accumulation of unreacted wastewater within the influence zone limits oxygen transport. Thus, a cascading type of failure mode may ensue, wherein the influence zone gets bigger and bigger as it gets less and less effective.
- Cesspools, favored in some regions, avoid the use of septic tanks. Untreated wastewater from a source is dumped into and partially treated by natural processes in the pool of an underground pit, and, the the wastewater infiltrates into the influence zone of soil surrounding the pit for futher treatment. Phenomena and problems similar to those described for leach fields will exist in cesspool influence zones.
- Thus, there is a need for alternatives to the costly or sometimes physically impossible remedy of adding to or replacing the leaching system. And, if good technology is at hand, the possibility arises for putting in a smaller system initially and reducing cost, for providing greater margin of safety in any given system, or for allowing growth in use of an existing system.
- Various approaches to enhance the capacity of leaching systems have been tried, reflecting different concepts of both failure and remedy. Chemical remedies in the forms of solvents, enzymes, and other proprietary formulations, for deposit into the wastewater line with wastewater, are commercially sold, but most are disdained or ignored by professionals. U.S. Pat. No. 5,588,777 of Laak discloses the injection of soap into the leach field. U.S. Pat. No. 5,597,264 of Laak discloses a method of periodically back flushing the leach field with water. U.S. Pat. No. 4,333,831 of Petzinger describes the type of problem mentioned above, solving it by using evaporation chambers in substitution of any leach field. U.S. Pat. No. 3,907,679 of Yost describes a system in which low pressure air is forced through a septic tank and then into a long coil of wastewater piping, so wastewater evaporates into the air and is discharged to atmosphere. U.S. Pat. No. 3,698,194 of Flynn describes how air is blown into a conduit of a leach field and vented from risers at the remote end of conduit, to cause evaporation of liquid in, and to dry out grease in, the conduit, during periods when the conduit is not being used for wastewater treatment. U.S. Pat. No. 4,013,559 of Johnson describes how air is introduced into the septic tank, flowed through unique vertical concrete panel leaching system units, and then discharged to atmosphere, to encourage aerobic conditions in wastewater within the panels. However, none of these prior art technologies seem to have found wide spread use. Thus, there is a continuing need for new ways to enhance the design and performance of leaching fields, both as they are originally installed and for when there are in need of rejuvenating.
- An object of the invention is to provide means for improving the function of septic tank type disposal systems and leach fields, to remedy failures, or forestall failure, or improve performance, in ways that are economical and practical. A further object of the invention is to effect desirable biochemical and physical conditions within the influence zone of a leach field. A still further object is to provide a way of sustaining or rejuvenating leach field performance while at the same time enabling continuous use of a septic tank type wastewater system.
- In accord with the invention, when wastewater is flowed from a primary wastewater processing unit, such as a septic tank, through a conduit, and into an influence zone in the soil, a significant pressure differential with atmospheric pressure is created, as gas, comprised of air or other biochemically active gas, flows between the conduit and the influence zone, in an amount effective for physical and or chemical change within the zone. In further accord, the flow of active gas is sufficient in amount to make the composition of gas within the influence zone effectively different from the composition which exists therewithin, in the absence of such flowing. Thus, if the leach field is functioning properly, the invention maintains or improves such; and, if the field is failing, the invention will restore part or all of the function. In one embodiment, air flows from a conduit, into and through the influence zone, in the same direction as the wastewater flows. In another embodiment, air flows from the influence zone and into the conduit. In both embodiments, an air mover such as a blower or vacuum pump establishes a significant pressure differential in the influence zone.
- In a preferred embodiment, a blower pressurizes the system conduits relative to atmosphere, and air flows through the influence zone, the adjacent soil, and ultimately back to atmosphere. If the influence zone is saturated, the pressure of air causes the water in the influence zone to physically move away from the conduit and the zone is de-saturated. When not fully saturated, the pressure of air flow causes physical gas exchange, to make the composition of gas in the influence zone more near that of atmosphere. In another embodiment, air flows similarly, but from an unpressurized conduit to an auxiliary pipe which is buried in the soil and maintained at below atmospheric pressure. In another embodiment, and air mover lowers the pressure of gas in the conduit and air flows from atmosphere, through the soil and influence zone and into the conduit. In another embodiment of the invention, air flows from a pressurized auxiliary pipe buried in the soil adjacent the trench, and into a conduit vented to atmosphere. In another embodiment, air is introduced into the bottom of the leaching trench by a pipe diffuser or by pipes which run lengthwise within the trench. In preferred practice, for a wastewater system embodying typical conventional soils, the differential air pressure between the conduit and atmosphere is at least 2.5 mm, preferably about 7.5 cm or more, water column, in order to produce a desired level of biochemically significant flow through the influence zone. When, in preferred embodiments, air is flowed from a conduit into the influence zone, the pressure in the soil of the influence zone, about 15 cm from the inner boundary of the influence zone, will be at least about 0.03 mm water column, more preferably at least 0.8 mm.
- In further accord with the preferred process of the invention, the influence zone of a deteriorated system is substantially anaerobic in character, and flowing of air or active gas causes the change so that it becomes predominantly aerobic. In still further accord with the invention process, the quantity of air or other gas which is flowed into the influence zone provides oxygen substantially in excess of the stoichiometric quantity which is required for oxidation of the oxidizable constituents in the wastewater, as such constituents are typically determined by measurement of Oxygen Demand, in particular Biological Oxygen Demand (BOD). Optionally, a gas or liquid substance is added to the air to enhance biochemical activity.
- In still another embodiment, the auxiliary pipe is buried under the trench or is within the trench. A membrane is optionally placed within or on the soil, to control the direction in which air travels from or to the soil surface. The air flow of the invention may be maintained continuously or intermittently, with and without simultaneous flow of wastewater in a preferred practice of the invention, by means of a control system. To ensure good functioning of a system, a low volume of air is continuously flowed into the wastewater system and the air moves through the influence zone contemporaneously with wastewater.
- In further accord with the invention, apparatus for treating wastewater is comprised of a primary unit, such as a septic tank or other kind of reactor for primary processing of the wastewater, a leach field, for receiving wastewater effluent of the primary unit, where the leach field is comprised of a trench in the soil, a conduit within the trench, and soil adjacent the trench comprising an influence zone, and a means, such as a blower or vacuum pump, for producing a pressure differential between the conduit and the adjacent soil, where the pressure differential is significant enough to effect a physical change, such as forcing water from the influence zone soil, or to effect biochemically significant change in the biochemistry of the influence zone.
- In preferred apparatus embodiments, there is a means, such as a mechanical check valve or a water trap, in the pipeline of the wastewater system, so the effect of applied pressure or vacuum is limited to localized parts of the wastewater system. In one instance, there is a check valve in the distribution pipe, which runs from a septic tank or the like to a distribution box, or other distribution piping, and air pressure is injected at one or more selected points in the distribution piping or conduits. In another instance, there is a check valve in the wastewater line downstream of the stack vent and upstream of the point at which pressurized air is injected. In still other embodiments, pressure or vacuum is applied to the wastewater line running into the septic tank and a check or other valve is present upstream of the point of connection to the wastewater line of the blower or vacuum pump source of differential pressure. In another embodiment, a blower is in the stack vent of the system. Use of the valve means enables use of the system for processing wastewater simultaneously with use of air flow. A check valve bypass line, temporary storage reservoir and pump are optionally in the wastewater line to further aid in the objective of continuous use. The duration or periods during which air is flowed is optionally controlled by a control system which senses the composition or pressure of gas or liquid in vicinity of the influence zone or elsewhere in the wastewater system.
- In a further embodiment of the method of the invention, the apparatus is configured so that there is a void space above the soil surface of the influence zone, through which wastewater flows downwardly. For instance, the void might be the space within an arch shape chamber or the spaces amongst stones within a trench. The water is first flowed in sufficient quantity and rate until it accumulates as a pond above the soil surface. The air pressure is applied to the void, to give impetus to the natural flow of water. Then, the application of air pressure is ceased, and either the water flow is resumed right away, or there is a period of quite time which is substantially longer than the time of applying air pressure. The cycle may be repeated continuously. The process saves energy by decreasing the duration of air mover operation.
- Preferably, the amount of air or other gas provides a quantity of air per unit time of system operation which quanity is many times greater, e.g., 10 to 25 times or more, than the quantity which theoretically would satisfy the biological oxygen demand of the wastewater.
- The invention is effective in improving the operation of leach fields in a cost-effective way. Leach field performance and biochemistry are improved and maintained through use of the system. The invention can be applied to existing installations and new installations. It is quite useful for rejuvenating the function of a system which has been either under-designed or over-used.
- The foregoing and other objects, features and advantages of the present invention will become more apparent from the following description of best mode embodiments and accompanying drawings.
- FIG. 1 is a perspective view of the basic elements of a prior art septic tank wastewater system, having a composite of leaching field trench types.
- FIG. 2 is a elevation cross section through the pipe and stone filled trench portion of the leach field of the system shown in FIG. 1.
- FIG. 3 is a elevation cross section through the arch shape leaching chamber-filled trench portion of the leach field of the system shown in FIG. 1.
- FIG. 4 is a semi-schematic, part-cross sectional, side elevation view of a septic tank type wastewater system having means for creating positive pressure gradient and outward air flow in the soil adjacent the leach field trench.
- FIG. 5 is a semi-schematic cross sectional end view of a portion of a leach field, analogous to the views of FIGS. 2 and 3, showing how pressure-vacuum auxiliary pipes are buried in the soil laterally adjacent the chamber-filled leach field trenches. It also schematically illustrates an associated control system.
- FIG. 6 is a view analogous to FIG. 5, showing one of a plurality of pipe and stone filled trenches having an underlying auxiliary vacuum pipe; together with a graph showing how negative pressure varies with depth within the soil and apparatus shown in the left of the Figure.
- FIG. 7 is a view analogous to FIG. 5, showing one of a plurality of chamber filled trenches with one of a multiplicity of spaced apart pressure-vacuum auxiliary vertical pipes adjacent the trench.
- FIG. 8 is a semi-schematic elevation view illustrating how a pressurized air line and a check valve are positioned in the wastewater line upstream of a septic tank through which air flows.
- FIG. 9 is a view like FIG. 8 showing a J-trap check valve used in substitution of the mechanical check valve shown in FIG. 8.
- FIG. 10 is a view like FIG. 8, showing a check valve in a bypass line for a valved wastewater line.
- FIG. 11 is a view like FIG. 10, showing a reservoir and pump for receiving and forcing wastewater downstream into the septic system while it is pressurized.
- FIG. 12 is a view like FIG. 10, showing a variation on the apparatus illustrated in FIG. 11.
- FIG. 13 is a fragmentary view like the view of FIG. 4, showing a blower positioned in the stack vent line.
- FIG. 14 is a view like FIG. 3, showing an oblong air distribution diffuser lightly buried in the soil beneath the bottom of a leaching chamber.
- FIG. 15 is a view like FIG. 2, showing two air distribution perforated pipes within the stone of the trench.
- Reference should be made to the Background section hereof for a description of various components, processes and environment which relate to both typical septic tank wastewater systems and the invention. FIG. 1 illustrates components of a typical septic tank wastewater system, familiar in the prior art. Wastewater flows through
wastewater line 18 from a dwelling or other source to aseptic tank 20. Wastewater flows fromtank 20, through a distribution system. In particular, the wastewater flows throughdistribution pipeline 22, todistribution box 30; and, then throughfurther distribution pipes 56 to theleach field 40. FIG. 1 shows a composite of two familiar types of leaching field construction. FIGS. 2 and 3 respectively show elevation cross section views through each of the two types. In two branches, or laterals, of theleach field 40 which is shown, atrench 35 is filled with crushed or naturallysmall stones 36 typically about 2.5 cm in dimension, (hereafter referred to as “stone”); and, aperforated pipe 32 distributes wastewater along the trench. The wastewater issuing from thepipe 32 may be temporarily stored in the voids within the stone; and, as indicated by thearrows 54, it then flows into the soil 38 (also called soil profile) beneath thesurface 42 of the earth through the bottom and or side walls of the trench. Atypical biomat 44 forms on and within the surface of the trench. Additional biomat, not shown, will typically be present on the stones in the trench, and may be present to such an extent as to run like a membrane across stones which lie at the perforations or openings of the pipe. While typical, a biomat will not necessarily be present in a wastewater system. - Referring to FIG. 3, in one branch, or lateral, of the
leach field 40, the trench is filled by a string of interconnected molded arch shapedplastic leaching chambers 34, such as Infiltrator® chambers. In many respects the functioning of the chamber system is similar to the stone filled trench and thus will not be repeated. Wastewater flows into the hollow interior of the chamber frompipe 56, where it may be stored temporarily, and it then flows into the soil, out the open bottom wall of the trench and through perforations in the sidewall, as indicated byarrows 54. The chamber defines and maintains the trench, and provides the conduit means for distributing wastewater along the trench. Sometimes, a pipe, which is a continuation ofline 56, runs along the length or a chamber interior peak to abet distribution of wastewater within a string of interconnected chambers. The side walls oftrench 35 are defined by the chamber walls and the bottom is parallel to the base of the chamber. Sometimes, the trench is made larger than the chamber, and crushed stone surrounds the chamber. From the foregoing it will be appreciated that both thechambers 34 and perforated pipes and conduits which both convey and disperse wastewater at different locations. - In both types of popular leach field constructions the infiltration rate into soil is often limited at least in part by the presence of one or more biomat layers. And, in both types there will be within the soil adjacent to the trench an
influence zone 50, having a nominalouter boundary 52, where the wastewater is (or should be, in a properly functioning wastewater system) largely renovated, or biochemically converted into a more environmentally benign form, prior to re-introduction into the ground water. The geometric definition of the influence zone is somewhat arbitrary and it can vary in dimension with time, as will be appreciated from the discussion in the Background and herein. In the drawings here, theouter boundary 52 is imaginary and not intended to represent any limiting dimension or proportion. While the invention is described in terms of soil of the earth, it will be understood that such term comprehends installations comprised in whole or part of artificial porous material such as sand and gravel and other particulate media. - The distribution portion of the FIG. 1 system includes a
typical distribution box 30, which is intended to balance flow between the branches of the system. In some septic systems there is only one branch, or several legs of the leach field are connected in series, in which case the distribution box is omitted, and the invention will be understood as being applicable in obvious ways to such systems. There are other commercial and non-commercial devices which are useful as conduits, in substitution of the stone filled trenches and chambers in leach fields, for instance, concrete galleries, leaching pits, also called “dry wells”, and drip line, as used in irrigation systems. In the generality of the invention herein, chambers and stone-trench pipes, dry wells, galleries, and all other substitutional devices—whether surrounded with small stone or buried directly in soil, are all considered conduits of fluid, within a context that some serve other functions as well. For example, cesspools and injection wells are also considered as comprising conduits and as functioning in part at least as leach fields. Cesspools are devices that function as both a primary unit and a leaching unit. Typically, raw sewage is introduced directly from the source, and as biochemical action takes place in the pool, the wastewater percolates into the surrounding soil. In injection wells, wastewater is pumped into the earth through a vertical pipe so it disperses into material beneath or around the pipe. Most of the rest of the description here uses the example of leaching chambers. - A main part of the invention comprises pressurizing or evacuating leach field conduits, relative to atmosphere. Pressurizing is described first. FIG. 4 shows a semi-schematic side elevation view of a gravity flow septic tank system, which is an improvement on the essential system shown in FIG. 1. A
wastewater line 18 runs downwardly from building 60 toseptic tank 20, for primary processing. Wastewater from an unshown sanitary appliance or other source is introduced intoinlet end 62 of the wastewater line. Gases, which come up the wastewater line from the septic tank, are vented throughstack vent 58 which protrudes above the building roof. Whenwastewater 64 flows into the septic tank, baffles 66 prevent floating solids from moving out of the tank an into the first part of the distribution subsystem,effluent exit pipe 22. The primarily treated wastewater flows from the septic tank, throughcheck valve 70, intodistribution box 30, and then intoleach field 40 which is comprised of several parallel strings of leachingchambers 34, one of which strings is shown.Blower 71 causes pressurized air, drawn throughair inlet pipe 72 to flow downair pipeline 68 and into the distribution box. Checkvalve 74 protects the blower from back flow of wastewater and smelly gas when it is not in operation. An odor-absorbing charcoal filter may optionally be used with or without the check valve. - When the
blower 71 is activated, the air pressure increases in the leach field. Checkvalve 70 prevents flow backward upeffluent line 22. Referring to FIG. 4, with reference to FIG. 2 and FIG. 3, the pressure within the leaching chambers is raised sufficiently to cause flow of air through thebiomat 44, if any, and through the portions of the trench walls to which air passing through the chamber walls has access. The air flows into theinfluence zone 50. From there, the air may flow in various directions within thesoil 38, ultimately escaping fromsoil surface 42 to atmosphere. Thus air flows serially through the conduit interior, the trench wall, and the influence zone, in the same direction as wastewater flows. Should there be a substantial quantity of water in the soil of the influence zone when the blower is started, the pressure of the air will desirably hasten the flow of water out of the influence zone. Some air may move directly upwardly from the trench interior to the surface. If the soil above the trench is saturated, as it may be in a severely failed leaching system, upward flow should be helpful in restoring the system. In experiments, it has been found that upward air flow is not a particular problem. In many systems, the soil tends to be compacted above the trench, which inhibits such flow. As discussed below, a barrier on or in the soil above a leach field trench will tend to inhibit upward flow. - The air flow into the conduit is maintained for a desired time, according to the result sought and obtained. After a time, air flow may be ceased, so the system resumes its normal operation; or, the system may be used during the time of air flow, as described below. Typically, a low power centrifugal blower is sufficient for producing the pressure differential which induces flow through the soil. The means for providing pressurized air will depend on the resistance of the air flow path. A regenerative type blower is used if a relatively high pressure is needed. Alternately, other means for flowing air may be used, such as blowers, fans, compressors, etc., according to the air moving performance required and the price of the component. Unless stated otherwise, all pressures stated herein are gage pressures, i.e., relative to atmosphere.
- Biomat is normally anaerobic. To the extent such is present, air flow will tend to make it at least temporarily aerobic, thus engendering desirably different biological or chemical reactions which alter and reduce the biomat. In one mode of the invention, air is forced into the influence zone and beyond, along the same general flow paths which wastewater has. Obviously, to the extent the influence zone and adjacent soil are saturated, there will be a physical/hydraulic effect, as forcing air into them will tend to unsaturate them. To the extent the influence zone is not appropriately aerobic, the flow of air tends to make it so, both by physical displacement and by desirable biochemical activity. If there is an accumulation of oxygen-demanding constituents within the influence zone and surrounding soil, they will be desirably oxidized and reduced in amount. To the extent there is excess undesirable gas in the soil, such as methane, carbon dioxide and hydrogen sulfide, they will be incorporated into the air stream and carried away, e.g., by diffusion in accord with the law of partial pressures; and, the changed environment will selectively affect their production.
- Thus, in synopsis, the invention process maintains or improves, as the case may be, the function of a leach field by (a) a physical (mechanical, pneumatic, hydraulic) effect; and (b) a chemical and or biological effect, which for simplicity if referred herein to as a biochemical effect, or in related fashion, to a change in biochemistry.
- With respect to the biochemical effect, it is generally accepted that in a major way the efficacy of the influence zone in treating wastewater depends on the soil within the zone comprising a predominantly aerobic environment, as such is contrasted with an anaerobic environment. In a typical failed system where for one reason or another the influence zone is anaerobic, the capability for treating wastewater is as little as one-tenth that of a desirable aerobic environment which enables aerobic metabolism and oxidation. An aerobic environment is said to exist when the oxygen tension is sufficient to predominantly sustain the growth of aerobic bacterium. See Chapter 10 of the textbook of R. Atlas, “Microbiology, Fundamentals and Applications,” MacMillan Publishing Co., New York (1984). For this description, an aerobic soil is one which is macroscopically aerobic, e.g., the preponderance of the volume of the soil of interest has oxygen tension sufficient for sustaining predominantly aerobic bacterium. An anaerobic soil in this description is one which is not aerobic. Nonetheless, within a mass of aerobic soil, such as the influence zone, the environment may vary from point to point, and anaerobic conditions can exist within a predominantly aerobic environment. For example, anaerobic micro-pores may be present within an array of aerobic macro-pores.
- The gross environment in the influence zone can be looked at in another way, according to principles of stoichiometry. As is conventional in wastewater flow analysis, wastewater can be characterized according to Oxygen Demand. Oxygen Demand is a characterization of how much oxygen is needed to effectively treat the oxidizable constituents in the wastewater to make them environmentally benign. Oxygen Demand is usually divided into two constituents, namely Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD). COD is commonly measured by the so-called Hach Method 8000. For wastewater systems associated with habitations, BOD is the commonly used parameter of interest. It is commonly measured in accord with United States Environmental Protection Agency Standard 405.1. Stoichiometry, as applied here to oxygen demand, refers to the chemical balance between an oxidizable material and oxidizer, in this instance, within the influence zone. If the influence zone receives a quantity of air which is stoichiometric, it means the quantity is exactly that which is necessary for complete theoretical oxidization of the oxidizable matter in the zone. In real situations, there are imperfect mixing and other influences, and to achieve full oxidation, some excess air (oxygen) is required. Thus, from this viewpoint, the desired aerobic influence zone will be characterized by oxygen-bearing gas flow over time, e.g., hours, which is in substantial excess of stoichiometry for the oxidizable constituents of the wastewater entering the zone over the same time. The excess stoichiometric air flow can derive from artificial means, such as through use of the invention, by natural means such as migration through permeable soil, or by a combination of those. As an example of such practice, for the system referred to in connection with Table 1, a continuous flow of 280 l/minute of injected air provides 50-100 times the stoichiometric quantity for a typical about 1200 l/day wastewater stream.
- Accordingly, in the invention, air is characterized as an active gas. It maintains or alters the composition of constituents and biochemistry of the influence zone. It contains oxygen and enables oxidation. Accordingly, other active gases may be used with or in substitution of air. For instance, oxygen or ozone enriched air may be used for better activity, and an oxygen-helium mixture may be used for a combination of greater fluidity and activity. Optionally, liquid or gaseous additives, such as reactive substances like hydrogen peroxide, surfactants, and the like, may be introduced into the air stream in
line 68 fromadditive system 76, by pumping or other obvious means. See FIG. 4. Alternatively, they may be introduced separately into the leach field conduits at the distribution box,distribution pipes 56, or chambers. Included within the effects of such additives will be to promote wetting, to act as solvents, and to increase oxidization or to promote other biochemical activity beyond what air induces. - Thus, in one aspect of the invention, an influence zone will be saturated with water and the pressure and flow within the soil of the influence zone is sufficient to unsaturate it. In another aspect of the invention, an influence zone will initially have a composition that is deficient in oxygen, being biochemically significantly less than the volume percent oxygen in air, and it will be changed so it approximates the composition of air. For instance, a starting composition of 14-19% oxygen will be changed to 20-21%, at a point about 15 cm from the inner boundary of the influence zone. In another aspect of the invention, the influence zone and surrounding soil will have constituents, in addition to oxygen, which are substantially different from the composition of air. For instance, carbon dioxide may exceed 2%,
methane 1% and hydrogen sulfide 0.005%. Use of the invention will change such values in the direction of the composition of air. - In the invention process there will be a flow into the influence zone of a quantity of gas which is effective. That is, the quantity will produce part or all of the above described desired physical or chemical change. Of course, the quantity or total mass of gas put into the influence zone is a product of the flow rate and time. The flow rate of the air within the soil profile will depend on the permeability of the particular soil profile and the applied differential pressure. Generally, it is an object to keep the air mover small for purchase and operating cost and noise reasons. Thus, in one mode an air mover is run continuously to pressurize the leach field, with or without simultaneous use for wastewater. In another mode the air mover is run intermittently, either during periods of wastewater use, or in periods of non-use.
- In a primary aspect of the invention, the amount of gas which is flowed into the influence zone is biochemically effective. Put another way, the air flow is sufficient in quantity to alter the biochemical conditions in the influence zone from those conditions which would exist in the absence of flowing, to a degree which is significant to the treatment of wastewater and soil. What is meant by biochemical or biochemistry is described above. Another primary aspect of the invention is to physically move water from the influence zone and to replace it by air to a degree sufficient to create an aerobic region in part or all of the influence zone and or to increase the permeability of the zone. What is an effective amount can vary with the starting condition in the influence zone. Thus, an effective amount of gas will change the zone so that treatment of wastewater, which simultaneously or subsequently enters the zone, will be significantly better treated. Thus, one or more of the following parameters will be meaningfully and significantly affected: the quantity of wastewater (e.g., volume and oxygen demand) which can be handled in a unit volume of influence zone will be increased; the quality of the effluent from the influence zone will be higher in the context of common environmental standards for underground water, the permeability of the zone will be increased; the pressure necessary to cause a unit of gas flow through the zone will drop; the pressure gradient within the zone for a given flow of gas will drop, the zone will change in character from anaerobic to aerobic, the quantity of water resident in the zone at any given instant will decrease; the fraction of oxygen in the zone will increase; and, the fraction of gases associated with anaerobic activity, such as carbon dioxide, methane and hydrogen sulfide, will be decreased in the zone.
- It follows from the foregoing, that to get a significant quantity of air flow there must be a commensurate significant pressure differential applied across the influence zone. Usually, it is desired to effect the change in a short period—a matter of hours or days, which may lead the user toward higher pressures. A physical movement of water within the zone usually occurs in a matter or minutes; and, a significant change in biochemistry will usually occur in hours, and will approach equilibrium in hours or days. The rate at which the beneficial effects are achieved depend on the air pressure/flow, the initial and changed conditions of the influence zone (e.g. permeability, temperature, etc.), any continuing introduction of new wastewater having oxygen-demand, and so forth.
- During use, the soil profile around a properly functioning wastewater system leach field will be moist, inasmuch as tension and capillarity will cause water to be retained. Moisture provides a soil profile with a flow resistance significantly greater than that of dry soil. Thus, simply flowing air down a conduit of a moist leach field, where the end of the conduit is vented to atmosphere, does not achieve the objects and benefits of the invention. While the environment within the conduit may be affected, there will be insufficient static pressure within the conduit to induce flow into the surrounding soil, owing to the resistance of moist soil profile and biomat if any to flow. Obviously, if the influence zone is saturated, the chance for flow is even more remote. Experiments with perforated pipe and leaching chambers buried in sand more permeable than typical soil, using fans like those suggested by the prior art, fail to induce biochemically or physically effective flow into the influence zone. To obtain flow from a pressurized conduit that will significantly affect the influence zone of a typical leaching field within a matter of hours or days, in the desired ways described herein, the conduit static pressure will preferably be in the range 1-100 cm water column. Obviously, when a liquid is to be pushed from a saturated zone, the initial pressure required is higher than if there is no saturation. If there is saturation, and it is alleviated by air treatment, the necessary pressure drops. Likewise, when the biochemistry is changed, soil permeability tends to be increased, and the necessary pressure drops. Experiments to date for a typical system, described in connection with Table 1 below, have been conducted. Relatively low pressures and per unit area mass flow rates occur in the influence zone and surrounding soil. For instance, a blower providing 290-1400 l/minute at 2.5-100 cm water column may effectively be used in a leach field having an estimated trench area sidewall and bottom area of 74 m2. A nominal flow rate soil immediately adjacent the trench wall will be of the order of 0.26-1.3 m3/m2/minute. After treatment, a Table I kind of system might be biochemically maintained by a continuous flow from a lower capacity blower, for instance one with capacity of 1700 l/minute operating at static pressure as low as about 2.5 mm water column. In most applications, on-going or maintenance pressures will probably be higher, so it will be desirable to have a blower that produces at least about 7.5 cm water column pressure.
- Differential pressure may be applied for many hours, extending into days or continuous operation, to achieve the desired effects. Thus, it can be very difficult to detect flow and pressure gradients, the presence of which is inferred and implicit because there is a measurable change in the gas content of the soil during use of the invention, as shown by the example below. The efficacy of the invention is often best determined by desirable change in, or maintenance of, gas content of the soil. In particular, oxygen is made high; carbon dioxide, methane, hydrogen sulfide and nitrogen compounds are made or kept low; all in the direction of the content of atmospheric air or in a biochemical direction which is better than air for aerobic bacterium.
- The apparatus in FIG. 4 may be modified somewhat to make an alternate embodiment in which a vacuum, instead of pressure, is applied to the distribution box, distribution pipes or chambers of the leach field. Check valve70A is replaced by a manual or motorized valve. The valve is closed during vacuum operation—assuming the vacuum level is such that it would unacceptably draw the contents from the septic tank. Any liquid drawn toward the vacuum pump is appropriately trapped by common means, and the liquid is re-introduced into the wastewater line or septic tank. When a vacuum is applied, air is drawn from the surface of the earth, through the soil, the influence zone, any biomat, and into the chamber, in ways which will be appreciated from the other description here. The air drawn from the system by the vacuum pump may be exhausted to atmosphere. Thus, there is serial flow which is the reverse of that which is described when the conduit is pressurized. The leaching system cannot be used for processing wastewater from the septic tank during the time it is placed under vacuum.
- With reference to FIG. 5, in another embodiment of the invention, one or more pressure-vacuum perforated pipes72 (called auxiliary pipes hereafter) are installed, either as original equipment or as retrofit, in proximity to, and parallel to, the chamber-filled
trenches 35. Air is either drawn from thepipes 72 or forced into thepipes 72, so that the leach field is beneficially affected. In one mode,pipes 72 are connected to a vacuum pump and gas is pulled from the soil. Appropriate common traps and trap emptying means are used to handle any wastewater that is drawn into the auxiliary pipes and to the pump, and the trapped water is recycled to the septic tank or leach field. The evacuation ofpipes 72 pulls air from the chambers to the extent they are in communication with atmosphere by means of vents in the distribution box (e.g., in substitution of line 68) or chambers, or through the septic tank and stackvent 58, consistent with other discussion herein. - When auxiliary pipes are vented, air will be drawn from the
earth surface 42 downwardly through thesoil 38, as indicated by arrows in the Figure, according to the vacuum level, the permeability of the soil and conditions inside the chambers. Preferably, there is significant flow through the chambers and trench walls, to replicate to a degree the effect achieved when the chambers are pressurized, as described above in connection with FIG. 4. To encourage such,auxiliary pipes 72 are placed sufficiently close to the trenches/chambers, and deep enough, to create a pressure gradient across the biomat if any and within the influence zone. As shown in FIG. 5, a membrane, such asplastic sheet 96, is optionally placed in the soil profile above thepipes 72 to limit downward flow of air in between the chambers. When the chambers are not vented to enable air flow directly from atmosphere to the chamber interior, the membrane tends to cause the air to flow fromsurface 42 towards, into and through, the chambers. In one alternative, the membrane is a layer of relatively impermeable natural material, laid within the indigenous soil. In another alternative, the membrane is placed on theearth surface 42. Preferably, the membrane runs substantially horizontally; in other modes, the membrane may run vertically or at an angle with or without a horizontal membrane. In still another alternative, the surface of the earth is compacted or otherwise treated to lessen permeability and to thereby functionally create a membrane. - FIG. 6 shows a stone filled trench and
pipe 72, together with a coordinated graph showing the estimated nominal variation in pressure P versus depth from the surface. Thepipe 72 is beneath and parallel to a stone filledtrench 35 and evacuated. A sub-atmospheric pressure gradient is established along the arbitrary vertical reference line D, as indicated by the dashed line P on the right side of the Figure. The pressure gradient induces the air flow indicated by the arrows on the left side part of the Figure. The air flows through the soil above the trench, more freely through the spaces amongst the stones, and then vertically down through the soil beneath the trench, and into the pipe. Corresponding pressure gradients and flows will be inferred for chambers having evacuated auxiliary pipes directly below. - In an alternate embodiment of use construction in accord with FIG. 6,
auxiliary pipes 72 are pressurized to thus create a positive pressure gradient and related flow within the soil. This will be essentially the inverse of the phenomena just described for evacuated pipes. Thus, the pressure in the soil in vicinity of the trench, chamber, or pipe, as the case may be, will be supra-atmospheric and air will flow into the pipe and upwardly through the soil profile to the chamber and or soil surface. When thepipes 72 are beneath the influence zone, pressure or upward air flow may also retard the downward flow and escape of wastewater to ground water, which could be either desirable or undesirable depending on reactions in the influence zone. - FIG. 7 is a fragmentary picture which will be understood from its analogy to FIG. 5. FIG. 7 shows one of a plurality of spaced apart
vertical pipes 78, which is positioned adjacent one or more of the trenches, along the length of the trench, in place of thehorizontal pipes 72. Thepipes 78 have perforated lower ends 79, to enable air to flow into and from the soil. As for other like Figures, the flow of gases, according to whether the pipe is pressurized or evacuated, is indicated by the double-headed arrows.Pipes 78 may alternatively be angled downwardly so the lower pipe ends are positioned beneath the trench, rather than adjacent to it as shown. Thus, the term “vertical pipe” will encompass pipes which are generally running in an upward direction, whether true vertical or at an angle to such, in which case they are only generally vertical. The advantage of the use of vertical injection or suction pipes is one of easy retrofit. Combinations of horizontal vertical (and angled) pipes and means for interconnecting them to the source of pressure or vacuum will present themselves. The horizontal or vertical aeration pipes shown in FIG. 5 or 7, and the diffusers of FIGS. 14 and 15 discussed below, may be installed proximate or within individual trenches, or portions thereof, rather than generally throughout an entire leaching system, to cope with a localized problem. - The operation of the FIG. 5 embodiment, as well as operation of other embodiments of the invention, may be controlled as indicated by the schematic control diagram portion of FIG. 5. The composition and or pressure of gas in the influence zone or soil adjacent the zone is sensed using a gas sensor comprised of a
probe 74 and ananalyzer 76. The analyzer provides a first signal tocontroller unit 94 which compares the first signal to a desired reference point (characteristic of a desired reference gas composition or pressure) and provides a second signal to theair mover 71, to thereby modulate flow of air to or frompipe 68 andpipes 72, according to the difference between the first signal and the reference point. The air flow may be modulated by stopping and starting the air mover, or by increasing or decreasing the pressure. Pressure is alternatively measured within the conduit or something connected to it, because as indicated, a drop in static pressure for a given flow is a measure of leach field improvement. The reference composition is selected in accord with the teachings herein. For instance, the reference composition may be such as 20% oxygen, or less than 1% carbon dioxide. The reference pressure is selected in relationship to other parameters which measure the performance of the influence zone, and based on accumulated experience with like wastewater systems. - FIG. 14 is a view like FIG. 3, showing a chamber having a oblong
cross section pipe 94 called here a diffuser, buried at shallow depth beneath the soil at the base of the chamber.Diffuser 94 may be alternatively laid on the soil at the base of the chamber.Diffuser 94 is connected to a source of pressurized air, so pressurized air is forced into the chamber in an evenly distributed way, to achieve the desired effect which has been described in connection with FIGS. 5-7. FIG. 15 is like FIG. 14 and FIG. 3, showing aperforated wastewater pipe 32 in a stone filledtrench 35. Running along the length of the bottom of the trench are two small diameterauxiliary pipes 96 carrying pressurized air. In another alternative, thepipes 96 are shallowly placed in thesoil 38 beneath the trench, in manner analogous to FIG. 14. - Referring again to the FIG. 4, there is a further embodiment which is useful, when the leach field chambers are pressurized. It comprises using the characteristic of the septic tank outlet to provide the means which prevents the back flow of air toward the
wastewater line 18, instead of employingcheck valve 70. For instance, when the septic tank outlet is an elbow, the head or water in the septic tank may resist back flow pressures of 2-100 cm water column. If the septic tank by design permits through-flow of air, such as when a tee fitting is used instead of an elbow, then the septic tank outlet or inlet may be modified by blocking off the openings which permit air passage. When these circumstances exist, the flow of wastewater into and out of the septic tank may be maintained during air pressurization of the leach field, assuming the resultant increase in head at the inlet end of the septic tank is tolerable. This will be further understood by the discussion which applies to the use of a water trap valve upstream or downstream of the septic tank, below. - Another alternative system design is as follows. It is very common that a septic tank will enable unimpeded flow-through of gases, from outlet to inlet. When such is the case, the location of the
check valve 70 shown in FIG. 4 for the pressurized leach field may be changed. It may be moved towastewater line 18, upstream of the septic tank, and thepressurized air line 68 may be connected between the valve and the septic tank. FIG. 8 shows such a construction in semi-schematic fashion, comprisingcheck valve 80 inwastewater line 18. Of course, the septic tank cannot leak excessively out the top if this option is to be practical. A check valve which is useful in this embodiment and others described is a common horizontal flap type check valve sold in connection with PVC wastewater pipe of 7.5-10 cm diameter. Manually or power actuated mechanical valves referred to herein are likewise commercially available. - The side elevation semi-schematic view of FIG. 9 shows another way for preventing back flow which can be used in substitution of a check valve, namely J-
trap 82. The trap type is familiar for toilets and other plumbing appliances. Sometimes, it is referred to as a U-trap. Generally, the J- or U-type of traps, and any other functional equivalent, is referred to hereafter as a water trap. As illustrated in FIG. 9, wastewater water is retained in the base of the J-shape contour ofline 18. The asymmetrical nature of the J shape means that there is more resistance to upstream flow of a fluid, compared to downstream flow. Thus the J-trap is functions analogously to a check valve, in impeding flow of air and water in the downstream direction more than in the other direction. Obviously, the back flow resistance can be overcome by raising the pressure sufficiently high, but so can a mechanical check valve be overcome by sufficiently high pressure. Obviously, the depth of the J can be used to set the head to which the downstream part of the septic system can be subjected. In the generality of the invention involving pressurization, the valve in the wastewater line functions to limit upstream movement and the valve may be a mechanical or water trap. It will be appreciated that in certain circumstances a water trap valve may be functionally sufficient and thus useful on the downstream side of the septic tank. - FIG. 10 is a semi-schematic elevation view of a variation on FIG. 8. The
primary wastewater line 18 is fitted withvalve 80A.Bypass wastewater line 86, with associatedbypass check valve 82, provides a bypass around thevalve 80A.Valve 80A is kept open during periods when there is no air pressurization of the system, i.e., during use of the wastewater system as it takes place in absence of use of the invention. Thus, with appropriate pipeline angling and positioning, wastewater will not consequentially pass through the check valve. This eliminates possible noise that might be heard by occupants of the building, arising from operation ofcheck valve 82 as wastewater passes through. - FIG. 11 is a view like FIG. 10. It shows a plumbing arrangement which is useful when the pressure in the leach field, due to air flowing down
feed pipe 68, is more than the head of wastewater coming down the wastewater pipe can overcome. In such instance, thevalve 80B in themain wastewater line 18A is closed. This causes wastewater coming down thewastewater line 18 to accumulate inreservoir 84. By means of a reservoir level sensor system, thepump 87 forces wastewater throughline 86 and forces it into the septic tank.Check valve 82B prevents any back flow when the pump is not operating. - FIG. 12 is like FIG. 10 and shows still another plumbing variation. Flow to
reservoir 84 alongbypass line 86 is controlled byvalve 82C. When thevalve 82C is closed, wastewater flows along the main wastewater line throughcheck valve 82. When thevalve 82C is opened, wastewater preferentially flows downline 86 intoreservoir 84 from whence, according to signals from unshown sensors, thepump 87C is activated to force wastewater downline 86C to overcome the air pressure in the wastewater system. The apparatuses described in connection with FIGS. 10-12 may be alternatively installed inexit line 22 ordistribution line 56. - The elevation view of FIG. 13 shows how a
centrifugal type blower 71 can be placed in thestack vent line 58, when J-trap 92 (or a functional substitute, e.g., a plurality of appliances having integral traps), or a mechanical valve (e.g., on-off or flap-check), is present to prevent back flow of pressurized air, up thewastewater line 18 intobuilding 60. When actuated, the blower forces air downwardly in the stack, and into the septic tank. When not actuated, the blower allows wastewater decomposition gases to escape up the stack. Particularly for retrofit purposes, the blower may be placed at the upper end of the stack vent, exterior of the building. - For original installation or retrofit purposes, a kit of components, which cooperate when installed, may be provided, e.g., to an installer of wastewater treatment system owner. The kit may comprise all or part of the following: a means for connecting an air flow supply to a wastewater or a distribution line, a flow checking means, an air mover, and a control system.
- In the most likely way in which the invention will be used, the leach field conduits will not be vented to atmosphere along their lengths or at their ends farthest from the septic tank. However, the invention can be applied to such kinds of vented conduits. When the chambers are pressurized, there is an obvious disadvantage in that the air mover has to have capacity sufficient to achieve the necessary static pressure while accommodating the loss of air out the vent. Alternately, the vents are fitted with valves. And, as has been mentioned, in various modes of the invention, e.g. when the conduits have subatmospheric pressure, it is contemplated that the conduits will be vented through the septic tank and stack vent. For such modes, other vents into the conduits can have a positive or neutral effect.
- The following is an example of the practice of the invention. Pressurized air was applied to the wastewater line of a long-functioning single family dwelling septic tank type system. Table 1 shows selected representative measurements of composition of soil profile gas content and pressure over time. The septic tank permitted free flow-through of air, thus the pressure in the leach field conduits was the same as at the wastewater line. The leach field was comprised of two 30 m serially connected lengths of perforated pipe in stone filled trench. The indigenous soil was comprised of silt, with some clay and a trace of fine sand and gravel. The soil temperature adjacent the trenches was about 13 degrees C. The arrangement was like that shown in FIG. 8, with a
check valve 80 in the wastewater line. The air mover was a 93 w, 1700 l/minute blower. Soil gas composition was measured using a commercial gas analyzer and a probe which inhibits infiltration of surface air. See U.S. Pat. No. 6,018,909. Pressure was measured with the same kind of probe. The applied positive pressure at the wastewater line was continuous and ended at the time shown for the readings. It gradually declined as the flow increased with the passage of time. Wastewater use was continued during the test, with at an estimated 1200 l/day input. Readings S7S and S7D were taken in the influence zone, respectively at depths of 30 and 75 cm from the earth surface at the end of a 30 m first trench length. Reading S1S was taken at the inlet end of the same first trench. All readings were taken at 15-30 cm from the inner boundary of the influence zone, that is, from the outer surface of the stone filled trench, which was not well defined in the long-used system. Generally, subsurface pressure measurements can be quite variable, which is in large measure believed due to local variations in the essential soil. For instance, a horizontal worm hole may have a significant local effect. The data in Table 1 represent typical or average data. They show how the influence zone of the soil was desirably changed in the aerobic direction over time and how unwanted constituents were decreased. The methane reading for S6D is apparently anomalous.TABLE 1 Soil gas composition change as a function of time for a pressurized septic system. Conduit Volume Percent Parts Per Million Influence Probe Time Pressure Carbon Hydrogen Zone Pressure Location Hr mm H2O Oxygen Dioxide Methane Sulfide mm H2O S7S 0 0 20.5 0.84 10 0 0 16 200 20.1 1.18 5 0 0.050 408 120 20.9 0.1 0 0 0.025 S6D 0 0 19.1 2.00 0 0 0 16 200 19.6 1.56 0 0 0.065 408 120 20.4 0.98 15 0 0.050 SlS 0 0 14.3 >5.00 0 0 0 16 200 16.5 4.38 0 0 0.025 408 120 20.9 0.16 0 0 0.075 - In other variations of the invention, air may be applied continuously or discontinuously. Generally, it is desirable to limit the amount of time in which air is flowed, to decrease the cost of operating the blower or other air mover. Often, the dynamics of the system will permit discontinuous air flow. In some instances, water is flowed in alternation with the flow of air or other active gas. In many instances, such as in the case of a domestic dwelling, wastewater flow varies over the course of the day, and the time of flowing air may be varied in coordination with such. For example, a blower may be run for one hour of presumed non-use, during the nighttime hours. For another example, a blower may be run for two equally spaced apart half hour periods each day. As in these examples, the time for airflow may be relatively small as a fraction of the total time of a wastewater flow day. In another application, a dosing pump or other means periodically delivers water to the leach field from a septic tank or other sump.
- In a further embodiment of the invention, the leach field is periodically dosed with wastewater, sufficient to create ponding, or a standing water level, on top of the soil of the influence zone. For example, the inside of the conduit of FIG. 3 is supplied with water at a rate and quantity such that it accumulates within the chamber on the underlying influence zone. For another example, the trench of FIG. 2 is likewise supplied for a first period of time by flow through the perforated pipe, so that water accumulates to a certain level within the broken stone of the trench. When the pond is created, the flow of water is ceased. Then after some delay to allow natural percolation, or alternatively without delay, air pressure is applied to the conduit. The pressure is maintained for a certain second time period, which may be a matter of a quarter hour, or more or less. The air pressure time is sufficient to force the wastewater to flow through the influence zone downwardly and otherwise, and to cause air to flow into the influence zone. Then the air pressure is ceased and the system is allowed to remain quiet for a third period of time, which period of time is substantially greater, for example, two times or more greater, than the time during which air was flowed. During the third period of time, the oxygen which is delivered by the airflow has a biochemically beneficial effect within the influence zone, as has been previously described. Alternatively, the third time period may be essentially zero. Monitoring of system performance and the character of water exiting the influence zone will help determine what the third time period should be. Finally, the cycle is repeated again with another dosing of wastewater, nominally like the first cycle.
- In one mode of alternating air flow with water flow, engineering judgment is used to determine the times of flows and a simple cycle timer is used to control the system. In another mode, the wastewater system is fitted with a more elaborate control system comprising part or all of the following. A sensor, such as a float or other commercial liquid level sensor is installed in the void space. A signal from the sensor stops the inflow of water by the dosing pump, when the water reaches a predetermined level. Immediately, or after a timer-controlled period, the blower is energized by the control system, to apply the pressurized air. Then, an oxygen sensor embedded in the influence zone is used to determine when air has sufficiently flowed into the influence zone, and to stop the flow of air. A timer then determines when dosing is restarted. The timing and duration of dosing will obviously also be a function of the wastewater which is flowed into the system.
- In further practice of the invention, air is provided in an amount which is greatly in excess of the calculated amount which would be theoretically necessary to satisfy the oxygen demand of the waste water. Typically, such demand for a domestic dwelling will be primarily BOD. The following is an illustration of such a situation. A system has a flow of about 1140 l/day (about 300 gal/day) and a BOD of about 150 mg/l, resulting in a calculated oxygen demand of about 0.17 kg/day. Air is flowed to the leach field at about 2.5 cm (1 inch) water column pressure and about 285 l/min (10 cubic feet per minute) for one hour per day, so that the total air flow is about 17,000 l. Thus, there is a flow of about 4.5 kg of atmospheric oxygen through the system. And, the weight flow of oxygen gas was about 26 times the weight of BOD in the waste water. The BOD of the wastewater exiting the influence zone is tested and found to be about 1 to 5 mg/l.
- In another example, a commercial establishment has a flow of about 1500 l/day (350-400 gal/day) of about 1000 mg/l BOD to a leach field. Air is supplied on a continuous basis at the rate of about 2850 l/min (100 cubic feet per minute). Thus the input oxygen is about 1080 kg/day while the oxygen demand of the wastewater is about 2.6 kg/day. So the flow of oxygen in the air is about 400 times the amount of oxygen demanded by the wastewater. In the generality of the invention, the airflow per unit time provides at least several times the theoretical oxygen demand of wastewater per unit time. Typically, a unit of time that is convenient is a 24 hour day.
- While the septic tank system designs described herein are most widely used in connection with dwellings, the invention will be useful in wastewater systems which process wastewater streams from industrial, agricultural, food processing, commercial, etc., operations, which wastewater streams present the same disposal problems as domestic wastewater from habitations. In a septic tank system, the septic tank is a unit for primary processing or treatment of wastewater and the leach field provides secondary processing or treatment of the wastewater, as such terms are well understood in the art. Septic tanks are commonly known to comprise predominantly anaerobic environments. The invention will also be useful with leach fields which derive wastewater from other sources than primary units. Other devices, both aerobic and anaerobic, may be substituted for septic tanks as the primary (treatment) unit. For instance, an aerobic reactor which agitates the wastewater with air may be used.
- Although this invention has been shown and described with respect to a preferred embodiment, it will be understood by those skilled in this art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.
Claims (18)
1. A method of subsurface sewage treatment, wherein waste water is flowed from a conduit into an influence zone within soil, in which zone the biochemistry of the waste water is changed by biochemical activity, toward being environmentally benign, and wherein said waste water is then flowed within the soil away from the influence zone, which comprises creating a significant gas pressure differential within the influence zone, to thereby flow a biochemically or physically effective amount of gas comprised of air or other active gas within the influence zone.
2. The method of claim 1 , wherein the gas flow is sufficient to cause the composition of the gas within the influence zone to significantly differ from the composition of gas which is otherwise present in the influence zone, in absence of said gas flow.
3. The method of claim 2 , wherein the influence zone is changed from anaerobic to aerobic.
4. The method of claim 2 , wherein the measured oxygen in the influence zone at a point about 15 cm from the inner boundary of the influence zone is increased from less than about 20 weight percent to about 20 weight percent or more.
5. The method of claim 1 wherein said gas is flowed simultaneously with, and in the same direction as, the flow of wastewater.
6. The method of claim 1 wherein, for a unit time, the amount of air or other active gas which is flowed contains several times the calculated weight amount of oxygen which would theoretically satisfy the oxygen demand of the wastewater which is flowed into the system and then the influence zone.
7. The method of claim 1 wherein the unit time is a day and wherein the oxygen which is flowed in with the gas is at least 10 times that which would theoretically satisfy said oxygen demand.
8. The method of claim 7 , wherein the oxygen demand, measured in terms of BOD, of the wastewater is at least about 100 milligrams per liter, and wherein the flow of oxygen in the gas is at least about 2500 milligrams per liter.
9. The method of claim 1 , wherein the significant pressure differential is created by a blower.
10. The method of claim 1 wherein the gas pressure within the influence zone is at least about 0.03 mm water column above atmosphere at a point about 15 cm from the inner boundary of the influence zone.
11. The method of claim 10 wherein said gas pressure is at least about 0.08 mm.
12. The method of claim 1 , wherein at least a portion of the wastewater flows vertically downward through the influence zone from a void space thereabove, which void space is within or below said conduit, which method further comprises:
(a) flowing wastewater into the void space so that it flows into the influence zone for a first period of time;
(b) providing pressurized air to the void space for a second period of time, to thereby impel water through the influence zone;
(c) ceasing said providing of pressurized air for a third period of time, to enable the air pressure in the void space to naturally dissipate; and,
(d) repeating step (a) again.
13. The method of claim 12 wherein said steps (a), (b), (c), and (d) are repeated a multiplicity of times.
14. The method of claim 12 wherein said third time period of step (c) is at least two times greater than said second time period of step (b)
15. The method of claim 14 , wherein said third time period is about one hour and said first time period is less than about one quarter hour.
16. The method of claim 12 which further comprises the steps of:
(e) sensing the level of water within the void space, and generating a signal responsive to such;
(f) flowing wastewater into the void space at a rate and amount sufficient to cause water to accumulate within the void space and rise to a first liquid level, whereby a first level of water signal is generated; and,
(g) ceasing the flowing of wastewater and providing pressurized air in response to said first level of water signal.
17. The method of claim 16 wherein said steps (a) through (g) are repeated a multiplicity of times.
18. A method of rejuvenating a subsurface wastewater treatment system, wherein waste water is flowed from a conduit into an influence zone in the soil, in which zone the biochemistry of the waste water is altered by biochemical activity, which comprises creating a significant gas pressure differential within the influence zone, to thereby flow a biochemically or physically effective amount of gas comprised of air or other active gas into the influence zone.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/292,185 US20030173293A1 (en) | 1999-03-17 | 2002-11-12 | Method for subsurface aerated treatment of wastewater |
US10/830,271 US6923905B2 (en) | 1999-03-17 | 2004-04-21 | Apparatus for subsurface aerated treatment of wastewater |
US10/830,263 US6887383B2 (en) | 1999-03-17 | 2004-04-21 | Method for subsurface aerated treatment of wastewater |
US10/845,739 US7157011B1 (en) | 1999-03-17 | 2004-05-13 | Vent for leach field aeration |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12507099P | 1999-03-17 | 1999-03-17 | |
US09/526,381 US6485647B1 (en) | 1999-03-17 | 2000-03-16 | Method and apparatus for treating leach fields |
US10/292,185 US20030173293A1 (en) | 1999-03-17 | 2002-11-12 | Method for subsurface aerated treatment of wastewater |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/526,381 Continuation-In-Part US6485647B1 (en) | 1999-03-17 | 2000-03-16 | Method and apparatus for treating leach fields |
US09/526,381 Continuation US6485647B1 (en) | 1999-03-17 | 2000-03-16 | Method and apparatus for treating leach fields |
Related Child Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/830,271 Continuation US6923905B2 (en) | 1999-03-17 | 2004-04-21 | Apparatus for subsurface aerated treatment of wastewater |
US10/830,263 Continuation US6887383B2 (en) | 1999-03-17 | 2004-04-21 | Method for subsurface aerated treatment of wastewater |
Publications (1)
Publication Number | Publication Date |
---|---|
US20030173293A1 true US20030173293A1 (en) | 2003-09-18 |
Family
ID=22418062
Family Applications (3)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/526,381 Expired - Lifetime US6485647B1 (en) | 1999-03-17 | 2000-03-16 | Method and apparatus for treating leach fields |
US10/292,185 Abandoned US20030173293A1 (en) | 1999-03-17 | 2002-11-12 | Method for subsurface aerated treatment of wastewater |
US10/830,263 Expired - Lifetime US6887383B2 (en) | 1999-03-17 | 2004-04-21 | Method for subsurface aerated treatment of wastewater |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/526,381 Expired - Lifetime US6485647B1 (en) | 1999-03-17 | 2000-03-16 | Method and apparatus for treating leach fields |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/830,263 Expired - Lifetime US6887383B2 (en) | 1999-03-17 | 2004-04-21 | Method for subsurface aerated treatment of wastewater |
Country Status (8)
Country | Link |
---|---|
US (3) | US6485647B1 (en) |
EP (1) | EP1169270A4 (en) |
JP (1) | JP2002538961A (en) |
KR (1) | KR20020001755A (en) |
AU (1) | AU765035B2 (en) |
CA (1) | CA2361723C (en) |
NZ (1) | NZ513819A (en) |
WO (1) | WO2000055098A1 (en) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6969464B1 (en) * | 2001-01-17 | 2005-11-29 | Potts David A | Dewatering a leach field |
US20090145830A1 (en) * | 2007-12-06 | 2009-06-11 | S-Box Llc | Subsurface sewage disposal and wastewater treatment system |
US8070949B1 (en) | 2007-08-20 | 2011-12-06 | Ezflow, L.P. | Micro diffusion of oxygen for treatment and dispersal of wastewater in a drain field |
WO2011146470A3 (en) * | 2010-05-17 | 2012-03-01 | Presby Patent Trust | Apparatus and method for processing liquid waste |
US20120224994A1 (en) * | 2009-02-24 | 2012-09-06 | John William Steiner | Air cleaning apparatus |
WO2013056055A3 (en) * | 2011-10-14 | 2013-06-13 | Presby Patent Trust | Liquid waste treatment apparatus |
US8815094B2 (en) | 2005-05-24 | 2014-08-26 | Presby Patent Trust | Fluid conduit with layered and partial covering material thereon |
US8974670B1 (en) | 2010-08-26 | 2015-03-10 | JRL Innovations Inc. | Method for enhanced aerobic activity and bio-mat control for onsite wastewater disposal systems |
US20180177146A1 (en) * | 2016-08-25 | 2018-06-28 | DroughtDietProducts.com | Liquid containment and focus for subterranean capillary irrigation |
Families Citing this family (37)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030070985A1 (en) * | 1999-03-17 | 2003-04-17 | Potts David A. | Apparatus for subsurface aerated treatment of wastewater |
JP2002538961A (en) * | 1999-03-17 | 2002-11-19 | ポッツ、デビッド、エイ. | Method and apparatus for leaching area treatment |
US20070068856A1 (en) * | 1999-05-10 | 2007-03-29 | Chaffee Kevin R | Wastewater treatment apparatus |
US6726401B1 (en) * | 2001-01-17 | 2004-04-27 | David A. Potts | Treatment of a leach field |
US6814866B1 (en) * | 2001-01-17 | 2004-11-09 | David A. Potts | Heating a leach field |
US6942800B2 (en) * | 2001-11-19 | 2005-09-13 | Michael J. Jungbauer | Septic system treatment process |
AU2002353441A1 (en) * | 2001-12-20 | 2003-07-09 | Arcaid International Limited | Percolation test apparatus |
US6821424B1 (en) * | 2002-04-25 | 2004-11-23 | Steven A. Branz | Wastewater treatment and dispersal system |
US7300577B1 (en) | 2002-04-25 | 2007-11-27 | Branz Steven A | Wastewater treatment and dispersal system |
US20040265061A1 (en) * | 2003-04-16 | 2004-12-30 | Chaffee Kevin R. | Subsurface wastewater infiltration system |
US7374670B2 (en) | 2005-06-03 | 2008-05-20 | Potts David A | High aspect ratio wastewater system |
US7465390B2 (en) * | 2004-06-04 | 2008-12-16 | Potts David A | Low aspect ratio wastewater system |
US20080135472A1 (en) * | 2004-08-19 | 2008-06-12 | Chaffee Kevin R | Trickling Filter Wastewater Treatment Device |
US8777515B1 (en) | 2005-02-28 | 2014-07-15 | James M. Donlin | Adaptable modular subsoil drainage system |
JP4088630B2 (en) * | 2005-02-28 | 2008-05-21 | シャープ株式会社 | Wastewater treatment equipment |
US8104994B1 (en) | 2005-02-28 | 2012-01-31 | Donlin James M | Subsoil drainage system |
US7662277B1 (en) | 2005-04-29 | 2010-02-16 | Kevin R Chaffee | Wastewater treatment apparatus |
US20080203002A1 (en) * | 2005-06-03 | 2008-08-28 | Potts David A | High treatment efficiency leach field |
US8636444B2 (en) | 2005-09-26 | 2014-01-28 | Frank Currivan | Fluid distribution system |
US20070187323A1 (en) * | 2006-02-10 | 2007-08-16 | Williams James A Jr | Environmental Waste Water Cultivation System |
US7708259B2 (en) * | 2007-02-23 | 2010-05-04 | Jesse Alan James | Self-standing weighted diffuser assembly |
US20090242492A1 (en) * | 2008-04-01 | 2009-10-01 | Rodney Ruskin | Subsurface wastewater disposal system |
GB2462091A (en) * | 2008-07-23 | 2010-01-27 | Charles Raphael Davila | Parallel sewer system |
EP3583938A1 (en) * | 2009-03-16 | 2019-12-25 | The University of Memphis Research Foundation | Chitosan pastes fro delivering an agent to a wound |
US8617390B2 (en) | 2010-11-11 | 2013-12-31 | David A. Potts | Wastewater system with pressure gradient transport |
US8834727B2 (en) | 2012-05-16 | 2014-09-16 | David A. Potts | Pressurized gas lifting and gas rejuvenation |
WO2014055838A1 (en) | 2012-10-05 | 2014-04-10 | Richard Couch | Subsurface sewage disposal system |
US9403692B2 (en) | 2013-03-15 | 2016-08-02 | David A. Potts | Wastewater treatment system |
US9809941B1 (en) | 2014-10-17 | 2017-11-07 | James M. Donlin | Flared modular drainage system with improved surface area |
US10267012B2 (en) * | 2016-02-23 | 2019-04-23 | Voidform Products, Inc. | Plumbing void construction unit |
US10378678B2 (en) * | 2016-02-23 | 2019-08-13 | Void Form Products, Inc. | Plastic void construction unit |
US10260222B1 (en) * | 2017-03-29 | 2019-04-16 | Suntree Technologies Holdings, Llc | Inline bioremediation liquid treatment system |
CA3073361A1 (en) | 2017-09-18 | 2019-03-21 | Drain Fields Patent Ab | Modular bio bed and ventilated system for waste water treatment |
CN107628716B (en) * | 2017-09-20 | 2020-09-01 | 华北理工大学 | Sewage treatment device |
CN108483621B (en) * | 2018-04-17 | 2020-04-21 | 西安建筑科技大学 | Optimal region for determining multi-stage water inlet process of sewage treatment and adjusting method |
US11118339B2 (en) * | 2018-05-17 | 2021-09-14 | Anvita Bansal | System for collecting and storing urine |
US11795679B2 (en) | 2021-07-19 | 2023-10-24 | Prinsco, Inc. | Asymmetric leaching chamber for onsite wastewater management system |
Citations (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2432889A (en) * | 1945-04-07 | 1947-12-16 | Arthur L Herrmann | Closure panel and strip therefor |
US3564854A (en) * | 1969-05-13 | 1971-02-23 | George W Berthold | Septic tank system |
US3680704A (en) * | 1971-03-11 | 1972-08-01 | Richard J Schaefer | Ozone sewage treatment apparatus |
US3698194A (en) * | 1971-02-01 | 1972-10-17 | John F Flynn | Automatically aerated leaching field system |
US3907679A (en) * | 1973-03-26 | 1975-09-23 | Coate Burial Vault Inc | Sewage treatment system including effluent evaporator |
US3951804A (en) * | 1973-02-23 | 1976-04-20 | Alvin Jack Smith | Aerated sewerage disposal |
US4013559A (en) * | 1975-11-19 | 1977-03-22 | Johnson Rollin W | Prefabricated panels for sub-surface sewage effluent and waste water disposal |
US4021338A (en) * | 1976-08-07 | 1977-05-03 | Wisconsin Alumni Research Foundation | Method for treating septic tank effluent seepage beds and the like |
US4588325A (en) * | 1984-07-26 | 1986-05-13 | Seefert Kenneth F | Modular rock replacing drain field apparatus |
US5336017A (en) * | 1989-04-24 | 1994-08-09 | Infiltrator Systems, Inc. | Leaching system conduit with interlocking end joint |
US5382363A (en) * | 1993-12-27 | 1995-01-17 | Boylen; Wilford M. | Septic system and method |
US5827010A (en) * | 1997-03-20 | 1998-10-27 | The English Oak Partnership, L.P. | On-site sewage treatment and disposal system |
US6018909A (en) * | 1996-05-28 | 2000-02-01 | Potts; David A | Subsurface soil conditioning |
US6162020A (en) * | 1998-12-04 | 2000-12-19 | Nca2Bioprocess, Inc. | Airlift pump apparatus and method |
US6576130B2 (en) * | 2000-07-17 | 2003-06-10 | North American Wetland Engineering, Inc. | Absorption field reclamation and maintenance system |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2432887A (en) | 1944-09-14 | 1947-12-16 | Lyman J Haviland | Sewage disposal apparatus comprising a septic tank and an evaporating tank having a vent |
US4333831A (en) | 1980-12-22 | 1982-06-08 | Petzinger Manfred W A | Evaporation septic tank sewage system |
US4826601A (en) * | 1986-08-01 | 1989-05-02 | Waste Treatment Technologies, Inc. | Sewage treatment method |
US5547589A (en) * | 1995-06-01 | 1996-08-20 | Carroll, Ii; Paul L. | Water recovery from a septic tank |
US5588777A (en) | 1995-06-30 | 1996-12-31 | Laak; Rein | Wastewater treatment system |
US5597264A (en) | 1995-06-30 | 1997-01-28 | Laak; Rein | Leaching field and method of making |
US5766475A (en) * | 1995-11-13 | 1998-06-16 | American Manufacturing Company, Inc. | Waste water disposal system |
JPH11216441A (en) * | 1998-02-02 | 1999-08-10 | Hosuparu Kk | Waste disposal method |
JP2002538961A (en) * | 1999-03-17 | 2002-11-19 | ポッツ、デビッド、エイ. | Method and apparatus for leaching area treatment |
US6814866B1 (en) * | 2001-01-17 | 2004-11-09 | David A. Potts | Heating a leach field |
US6726401B1 (en) * | 2001-01-17 | 2004-04-27 | David A. Potts | Treatment of a leach field |
-
2000
- 2000-03-16 JP JP2000605529A patent/JP2002538961A/en active Pending
- 2000-03-16 CA CA 2361723 patent/CA2361723C/en not_active Expired - Lifetime
- 2000-03-16 EP EP00916366A patent/EP1169270A4/en not_active Withdrawn
- 2000-03-16 AU AU37479/00A patent/AU765035B2/en not_active Ceased
- 2000-03-16 WO PCT/US2000/006799 patent/WO2000055098A1/en not_active Application Discontinuation
- 2000-03-16 US US09/526,381 patent/US6485647B1/en not_active Expired - Lifetime
- 2000-03-16 NZ NZ51381900A patent/NZ513819A/en not_active IP Right Cessation
- 2000-03-16 KR KR1020017011449A patent/KR20020001755A/en not_active Application Discontinuation
-
2002
- 2002-11-12 US US10/292,185 patent/US20030173293A1/en not_active Abandoned
-
2004
- 2004-04-21 US US10/830,263 patent/US6887383B2/en not_active Expired - Lifetime
Patent Citations (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2432889A (en) * | 1945-04-07 | 1947-12-16 | Arthur L Herrmann | Closure panel and strip therefor |
US3564854A (en) * | 1969-05-13 | 1971-02-23 | George W Berthold | Septic tank system |
US3698194A (en) * | 1971-02-01 | 1972-10-17 | John F Flynn | Automatically aerated leaching field system |
US3680704A (en) * | 1971-03-11 | 1972-08-01 | Richard J Schaefer | Ozone sewage treatment apparatus |
US3951804A (en) * | 1973-02-23 | 1976-04-20 | Alvin Jack Smith | Aerated sewerage disposal |
US3907679A (en) * | 1973-03-26 | 1975-09-23 | Coate Burial Vault Inc | Sewage treatment system including effluent evaporator |
US4013559A (en) * | 1975-11-19 | 1977-03-22 | Johnson Rollin W | Prefabricated panels for sub-surface sewage effluent and waste water disposal |
US4021338A (en) * | 1976-08-07 | 1977-05-03 | Wisconsin Alumni Research Foundation | Method for treating septic tank effluent seepage beds and the like |
US4588325A (en) * | 1984-07-26 | 1986-05-13 | Seefert Kenneth F | Modular rock replacing drain field apparatus |
US5336017A (en) * | 1989-04-24 | 1994-08-09 | Infiltrator Systems, Inc. | Leaching system conduit with interlocking end joint |
US5382363A (en) * | 1993-12-27 | 1995-01-17 | Boylen; Wilford M. | Septic system and method |
US6018909A (en) * | 1996-05-28 | 2000-02-01 | Potts; David A | Subsurface soil conditioning |
US5827010A (en) * | 1997-03-20 | 1998-10-27 | The English Oak Partnership, L.P. | On-site sewage treatment and disposal system |
US6162020A (en) * | 1998-12-04 | 2000-12-19 | Nca2Bioprocess, Inc. | Airlift pump apparatus and method |
US6576130B2 (en) * | 2000-07-17 | 2003-06-10 | North American Wetland Engineering, Inc. | Absorption field reclamation and maintenance system |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6969464B1 (en) * | 2001-01-17 | 2005-11-29 | Potts David A | Dewatering a leach field |
US9556604B2 (en) | 2005-05-24 | 2017-01-31 | Presby Patent Trust | Liquid waste treatment apparatus |
US8815094B2 (en) | 2005-05-24 | 2014-08-26 | Presby Patent Trust | Fluid conduit with layered and partial covering material thereon |
US8070949B1 (en) | 2007-08-20 | 2011-12-06 | Ezflow, L.P. | Micro diffusion of oxygen for treatment and dispersal of wastewater in a drain field |
US20090145830A1 (en) * | 2007-12-06 | 2009-06-11 | S-Box Llc | Subsurface sewage disposal and wastewater treatment system |
US20120224994A1 (en) * | 2009-02-24 | 2012-09-06 | John William Steiner | Air cleaning apparatus |
WO2011146470A3 (en) * | 2010-05-17 | 2012-03-01 | Presby Patent Trust | Apparatus and method for processing liquid waste |
US8501006B2 (en) | 2010-05-17 | 2013-08-06 | Presby Patent Trust | Apparatus and method for processing liquid waste |
AU2011256246B2 (en) * | 2010-05-17 | 2014-07-10 | Presby Plastics, Inc. | Apparatus and method for processing liquid waste |
US8974670B1 (en) | 2010-08-26 | 2015-03-10 | JRL Innovations Inc. | Method for enhanced aerobic activity and bio-mat control for onsite wastewater disposal systems |
US9352991B1 (en) | 2010-08-26 | 2016-05-31 | JRL Innovations Inc. | System for enhanced aerobic activity and bio-mat control for onsite wastewater disposal |
US9688556B2 (en) | 2010-08-26 | 2017-06-27 | JRL Innovations Inc. | Method for enhanced aerobic activity and bio-mat control for onsite wastewater disposal systems |
US9981867B2 (en) | 2010-08-26 | 2018-05-29 | JRL Innovations Inc. | System for enhanced aerobic activity and bio-mat control for onsite wastewater disposal systems |
US8999153B2 (en) | 2011-10-14 | 2015-04-07 | Presby Patent Trust | Liquid waste treatment system |
WO2013056055A3 (en) * | 2011-10-14 | 2013-06-13 | Presby Patent Trust | Liquid waste treatment apparatus |
US20180177146A1 (en) * | 2016-08-25 | 2018-06-28 | DroughtDietProducts.com | Liquid containment and focus for subterranean capillary irrigation |
US11944045B2 (en) * | 2016-08-25 | 2024-04-02 | Drought Diet Products | Liquid containment and focus for subterranean capillary irrigation |
Also Published As
Publication number | Publication date |
---|---|
EP1169270A1 (en) | 2002-01-09 |
NZ513819A (en) | 2001-09-28 |
US6887383B2 (en) | 2005-05-03 |
US6485647B1 (en) | 2002-11-26 |
US20040195177A1 (en) | 2004-10-07 |
JP2002538961A (en) | 2002-11-19 |
KR20020001755A (en) | 2002-01-09 |
CA2361723C (en) | 2006-08-29 |
AU765035B2 (en) | 2003-09-04 |
WO2000055098A1 (en) | 2000-09-21 |
AU3747900A (en) | 2000-10-04 |
CA2361723A1 (en) | 2000-09-21 |
EP1169270A4 (en) | 2004-09-22 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6887383B2 (en) | Method for subsurface aerated treatment of wastewater | |
US6923905B2 (en) | Apparatus for subsurface aerated treatment of wastewater | |
US6652743B2 (en) | System and method for removing pollutants from water | |
US6576130B2 (en) | Absorption field reclamation and maintenance system | |
Pell et al. | Infiltration of Wastewater in a Newly Started Pilot Sand‐Filter System: I. Reduction of Organic Matter and Phosphorus | |
US7309434B2 (en) | Apparatus and method for wastewater treatment | |
US5980739A (en) | Wastewater treatment method and apparatus | |
WO1998058881A1 (en) | Method and apparatus for biological treatment of waste water | |
Siegrist et al. | Design and performance of onsite wastewater soil absorption systems | |
US7118669B1 (en) | Wastewater treatment and dispersal system | |
US20100200502A1 (en) | Septic system remediation method and apparatus | |
US20050077237A1 (en) | Method for recovering a disposal trench with a biomat slime, and method for operating a waste treatment vessel | |
US7309423B1 (en) | Wastewater treatment and dispersal system | |
US6969464B1 (en) | Dewatering a leach field | |
CN109437393B (en) | High-load ecological ground sewage filtering treatment method | |
US7429320B2 (en) | Wastewater treatment system | |
CN205676317U (en) | A kind of unpowered high load capacity subsurface infiltration sewage disposal hybrid system | |
CN115072943B (en) | High-load underground infiltration system and treatment process for domestic sewage | |
US20220212951A1 (en) | Infiltration system management | |
JP2983209B1 (en) | Infiltration type wastewater treatment apparatus and method of laying it | |
Anderson et al. | Performance evaluation of in-ground passive nitrogen reduction systems (PNRS) | |
Amador et al. | NOWRA Conference 2005 AERATION TO IMPROVE THE WATER QUALITY AND HYDRAULIC FUNCTIONS OF SEPTIC SYSTEM LEACHFIELDS | |
JP3261463B2 (en) | Soil purification method for sewage | |
JPH0142756B2 (en) | ||
Aldrich | Pretreatment to Enhance Nutrient Removal with Constructed Wetlands |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: EXPRESSLY ABANDONED -- DURING PUBLICATION PROCESS |