WO1999032406A2

WO1999032406A2 - Improved effluent treatment system

Info

Publication number: WO1999032406A2
Application number: PCT/NZ1998/000184
Authority: WO
Inventors: Ulrich Michael Rambeck
Original assignee: Ulrich Michael Rambeck
Priority date: 1997-12-19
Filing date: 1998-12-17
Publication date: 1999-07-01
Also published as: NZ329455A; WO1999032406A3; AU1893199A

Abstract

The improved effluent treatment system provides a manmade biocenosis, sealed against the ground, preferably gravity-driven free flow, where inflow (Figure 1, numeral 4 and 9), waterlevel (Figure 2, numeral 18 and following adjoined parts) and outflow (Figures 1 and 2, numeral 6 and 10) can be controlled (Figure 2, numeral 18 and following adjoined parts). Three co-dependent components, gravel in layers (Figure 1, numeral 5 and 10), microorganisms amongst the gravel (Figure 1, numeral 5 and 10) and plants (Figure 1, numeral 8 and 11) create a two-stage treatment device (Figure 1, numeral 2 and 3) in which solids become separated from the effluent to remain on top of the filter body (Figure 1, numeral 5) and become transformed into a soil-peat similar structure with the help of the plant species phragmitis Australis (Figure 1, numeral 8). The solid free effluent percolates through the filterbody (Figure 1, numeral 5) and flows via a flange (Figure 2, numeral 15-16-17) the outlet-pipe (Figure 1, numeral 6 and 12) and a controlshaft (Figure 1, numeral 7) to the treatment area two (Figure 1, numeral 3) where the final cleansing takes place. A variety of marshland plants (Figure 1, numeral 11) assists the final cleansing process. The discharge out of the treatment area is the same like out of treatment area one (Figure 2, numeral 15-16-17; Figure 1, respective 2, numeral 6; Figure 1, numeral 14). The described installation gives an alternative to septic tank systems or any other effluent treatment devices.

Description

TITLE : Improved Effluent Treatment System FIELD OF INVENTION

This invention relates to an effluent treating system, and is applicable particularly, but not

exclusively, to the treatment of effluent containing solid material.

BACKGROUND

During the past few decades the complexity and efficiency of effluent treatment plants

installed by large urban developments and major cities has increased considerably.

While complexity and efficiency have increased, a number of problems still exist with

current treatment plants. These include the absence of effective methods and processes to

deal with the solid waste, generally referred to as "sludge", produced from such plants, and

the absence of smaller, more cost-efficient plants for smaller sized towns, rural and remote

areas, or even individual dwellings. These space requirements, costly maintenance and

environmental impacts of existing treatment plants often detract from the advantages of

treating effluent for reuse.

There is an absence of an effective, simple and low cost effluent treatment system which

solves a number of these problems, while remaining cost-effective and efficient over time.

OBJECT

It is therefore an object of the invention to provide an improved effluent treatment system, or

one which will at least provide the public with a useful choice. STATEMENT OF INVENTION

Accordingly in one aspect the invention may broadly be said to consist of an improved

effluent treatment installation comprising a plurality of filtering and treatment areas, said

areas having means for allowing the ingress of effluent into each area, means for the filtering

or treatment of the effluent, or means for both the filtering and treatment of the effluent, and

means for allowing the egress of the effluent from each of the treatment and filtering areas.

Preferably the installation is comprised of at least two filtering and treatment areas. It is

desirable to refer to these areas as the first treatment area and the second treatment area.

Where the effluent contains solid material, it is desirable to separate the solid material from

the fluid or liquid so as to treat both the material and the fluid or liquid separately. Hence

when the effluent is first passed into the first treatment area it is desirable to filter as much of

the solid material from the fluid or liquid as possible. Preferably any solid material separated

from the effluent is to be retained for treatment in the first treatment area. More preferably

said treatment area contains a plurality of filter means to effect the removal of solid material

from the effluent once said effluent is passed into the first treatment area and before it is

passed into the second treatment area.

It is desirable to separate as much of any solid material as possible contained in the effluent

from the fluid or liquid once the effluent has entered the first treatment area. To achieve this

it is preferable said filter means comprises a plurality of individual filter layers through

winch the effluent may pass, each individual filter layer containing filter material of a

particular type and size. More preferably the plurality of filter layers include a final filter layer, immediately under which is a top filter layer, a plurality of intermediate filter layers,

and a bottom filter layer.

Preferably, but not necessarily, each filter layer is of substantially the same depth.

Preferably said final, top, bottom and inteπnediate filter layers are arranged in order

depending on the size of the filter material contained in each layer. More preferably said

layers are arranged such that the bottom layer contains filter material having the greatest

diameter, the final layer contains filter material of the smallest diameter, and the intermediate

layers are arranged in order of decreasing filter material diameter from the bottom layer to

the final layer.

Preferably said filter material is comprised of gravel or some other similar type of non-

reactive sub-strata.

It is desirable to ensure the maximum amount of solid material is removed from the effluent

as it is passed through treatment area one. Preferably the final filter layer of treatment area

one comprises a mixture of sand and bark, or some other similar combination of materials.

Preferably means are provided to allow the filtered effluent to pass from treatment area one

to treatment area two. It is desirable to refer to this filtered effluent as outlet water.

Once any solid material contained in the effluent has been substantially removed by passing

the effluent through treatment area one, it is desirable to further subject the resulting outlet

water to a cleaning process in treatment area two. Preferably treatment area two contains substantially similar filter means as to those described herein for treatment area one. More

preferably said filter means may be arranged in a substantially identical configuration to the

filter means as herein described for treatment area one.

It is desirable to take advantage of the various biological characteristics of a variety of plants

for the treatment of the solid material extracted from the effluent, and the resulting outlet

water. Preferably the final filter layer of each treatment area is capable of supporting a

plurality of selected plants. More preferably the filter material provided in each treatment

area provides the required support needed for said plants to survive and prosper. Preferably

the final filter layer alone contains organic material such as peat or bark to achieve this.

It is desirable to use treatment area one for the purpose of treating the solid material filtered

from the effluent. Preferably the plants used in treatment area one are selected from

predetermined genera which shows suitable characteristics for assisting in the treatment of

the solid material. More preferably the plants used in treatment area one are capable of

creating root systems into the solid material and exhibit desirable characteristics in the

mineralisation of said solid material into a substantially soil-like material.

It is desirable to use treatment area two for the purpose of treating the outlet water filtered

from the effluent. Preferably the plants used in treatment area two are selected from

the outlet water. More preferably the plants used in treatment area two exhibit desirable

biological characteristics so as to assist in the treatment and cleaning of the outlet water. Preferably the first treatment area is elevated above the second treatment area. Where more

than two treatment areas are being used, it is preferable the first treatment area is positioned

above the second treatment area, this area itself being positioned above the third treatment

area and so on.

Preferably the required sizes of the filtering and treatment areas and the complexity and

composition of the filtering means may be determined through a number of criteria,

including, but not limited to, the expected volume and quality of the effluent, the expected

volume and quality of the filtered solid material, and the number of inhabitants from the

town, city or the like relying on the treatment plant.

It is desirable to ensure effluent under treatment, or any solid content of that effluent, is

contained within each of the treatment areas, irrespective of the location of said treatment

areas. Preferably then means are provided which prevent the uncontrolled egress of any

effluent under treatment, or any contents of said effluent, from the treatment areas.

Preferably means provided for the controlling of the ingress of the effluent and the treated

effluent, and the egress of same, are sealed to prevent the uncontrolled leaking of any

effluent under treatment or any contents of said effluent from the treatment areas.

In another aspect the invention provides an effluent treatment installation including a first

treatment zone and a second treatment zone, means for supplying fluid effluent to said first

treatment zone, said first treatment zone comprising filtering means for filtering out solids

therefrom, an outlet from the said first treatment zone for the supplying of filtered fluid to

said second treatment zone, wherein the first treatment zone supports one or more first plant species capable of utilising the solids filtered out by the filtering means, said second

treatment zone comprising a support zone for one or more second plant species capable of

producing secretions for the treatment of fluid passing through said second treatment zone,

and an outlet from said second treatment zone.

Preferably the second plant species are capable of releasing antibiotic secretions.

Preferably both the first and second plant species are helophytic.

In another aspect the invention provides a method of effluent treatment comprising the steps

of supplying fluid effluent to a first treatment zone and filtering out any solid material

contained therein from the effluent by passing said effluent through a variety of filtering

means, and then treating the solid material extracted from the effluent in said first treatment

zone, and then passing the filtered fluid out of the said first treatment zone to a second

treatment zone where further filtering may take place, followed by the treating and cleaning

of the filtered effluent in said second treatment zone, and the removal of the treated effluent

from said second treatment zone.

To those skilled in the art to which the invention relates, many changes in construction and

widely differing embodiments and applications of the invention will suggest themselves

without departing from the scope of the invention as defined in the appended claims. The

disclosures and the description herein are purely illustrative and are not intended to be in any

sense limiting. DRA WINGS

One preferred forai of the invention will now be described with reference to the

accompanying drawings in which;

Figure 1 shows a two stage effluent treatment system as herein described by the

specification; and

Figure 2 shows a cross-section of part of the effluent treatment system shown in figure

1.

PREFERRED EMBODIMENT

In figure 1 a two stage botanical effluent treatment plant 1 is shown.

In the preferred form of the invention, the treatment plant is separated into two areas, refeired

to for the purposes of this description as treatment area one and treatment area two, shown in

figure 1 by the numerals 2 and 3 respectively.

It is desirable for effluent being processed in the plant to move freely by the force of gravity

from treatment area one through to treatment area two, subject to any flow control

mechanisms in place to regulate the flow of the effluent through the facility. In the preferred

embodiment treatment area one is constructed above treatment area two so that a natural

downward flow of effluent through the facility is achieved. The sizes of treatment areas one and two will depend on a variety of criteria. In particular

however the effectiveness and efficiency of each effluent treatment facility is a factor of a

variety of integers including the quantity of effluent, the expected solid content of the

effluent, and where the treatment facility is being used to treat effluent from a community,

town or city, the number of inhabitants of the community, town or city.

In addition the shape and configuration of each treatment facility may be adjusted to fit the

geography of almost any installation site, and nearly any configuration may be created for

meeting the requirements and demands of the circumstances. However it is expected that

this type of effluent treatment system will require at least 40% more area than a conventional

treatment plant.

It is of course desirable to ensure any effluent treatment and the material extracted from the

effluent remains under the control of the treatment facility at all times. In particular each

facility will need to be designed to ensure material cannot leak from the treatment areas and

into the surrounding environment. In the preferred embodiment each treatment area will be

completely sealed from ground contact by a foil layer, reinforced concrete, or density-

enhanced clay, or any other kind of combination of materials which will guarantee the

integrity of the treatment areas. It is envisaged similar efforts will be required to seal the

inflow and outflow pipes, the control shafts, and any other channelling in use through the

facility. The function of the treatment plant is in two stages. Firstly treatment area one separates

solid material from the liquid, while treatment area two acts upon the output from treatment

area one, the solid-free liquid, in a treatment process.

In the preferred embodiment treatment area one is constructed as follows.

An inflow pipe 4 brings the effluent into treatment area one. In the preferred embodiment it

is expected some form of flow control mechanism will interact with inflow pipe 4, although

this is not shown in figure 1.

The effluent is passed over a filter bed 5, the purpose of which is to separate solid material

from the effluent, allowing solid-free liquid to pass vertically through the filter bed and on

into treatment area two via outflow pipe 6 and control shaft 7.

Filter bed 5 may be constructed in a variety of ways, but the general requirement is for the

filter material used in the bed to be arranged in order of decreasing size, such that the filter

material at the base of the bed has the greatest diameter, whereas the filter material at the top

of the bed has the smallest diameter. The combination of filter material chosen should reflect

the desire to ensure the maximum yield of solid material is left on the surface, allowing the

solid-free liquid to pass through to the next stage of the treatment process. For example, in

the preferred embodiment the filter bed consists of a number of layers of gravel or some

other similar non-reactive material, arranged as follows:

1. a coarse bottom layer, approximately 16-32mm in size and approximately 100mm

thick; 2. a second layer, approximately 8-16mm in size and approximately 50mm thick;

3. a third layer, approximately 4-8mm in size and approximately 50mm thick; and

4. a final layer of sand approximately 100mm thick, or a layer of sand approximately

70mm thick with yet another layer approximately 30mm thick on top of the sand

comprising a mixture of sand and peat or fine bark.

Other density and diameter combinations may be used depending on the volume and type of

effluent being treated, and also the weight constraints of the facility. Gravel is however

preferred as it provides very good permeability throughout the filter bed.

Once the solid matter has been separated from the effluent, it is desirable to further treat this

matter. To achieve this in the preferred embodiment reed 8 such as Phragmatis australis may

be planted in the surface of the filter bed, which provides the necessary biosphere for the reed

to grow. It is envisaged approximately three plants per square metre will be required. Reed

is particularly suitable for this purpose as it is able to create new root systems into the solid

matter filtered from the effluent, and by the process of mineralisation is able to convert this

filtering material into a soil-type material.

Other genera of plants may be used, and it is foreseen there may be particular advantages in

using species which, for example, could be used as a fodder source or as a renewable source

of building supplies, particularly where the facility is being used in developing countries. To ensure the quality and effectiveness of the plants being used in the system is maintained,

it is envisaged regular pruning and cutting back of the plants will be required, the off-cuts of

which may be removed and composted.

In the preferred embodiment treatment area two is constructed as follows.

Treatment area two comprises the actual cleaning and treatment area for the now solid-free

liquid effluent or outlet water, which flows into treatment area 2 via inflow pipe 9. It is

similarly constructed as treatment area one, having in the preferred embodiment a filter bed

10 consisting of three layers of gravel or some other similar non-reactive material, arranged

as follows:

1. a coarse bottom layer, approximately 16-32mm in size and approximately 100mm

thick;

2. an intermediate layer, approximately 8-16mm in size and approximately 100mm

thick; and

3. a final layer, approximately 4-8mm in size and approximately 100mm thick.

Again other density and diameter combinations may be used depending on the volume and

type of outlet water being treated.

If the outlet water contains no solid material, only one type of gravel or similar material is

required, ideally having a depth of 300mm and a particle diameter of 8-16mm. The inflow pipe 9 should preferably discharge the effluent into a coarse gravel area (with

particle sizes 30mm in diameter or larger) in the first instance so as to assist in the

oxygenation of the inflow outlet water.

A number of plants produce antibiotic secretions for their self-protection, thereby treating the

outlet water over time as it settles in treatment area two. To achieve this in the preferred

embodiment a variety of marshland plants 11 may be planted in the surface of filter bed 10,

which provides the necessary biosphere for the plants to grow and prosper. It is envisaged

approximately ten different genera of plants are required, with a planting density of 3 plants

per square metre. The recommended species of plants are as follows:

1. Eleocharis palustris;

2. Iris pseudacorus;

3. Schoenoplectus lacustris;

4. Mimulus luteus;

5. Filipendula ulmaria;

6. Juncus compressus;

7. Lythrum salicaria;

8. Juncus inflexus; 9. Menta aquatica; and

10. Carex acutiformis .

.Any other combination of similar helophytic plants may be used to achieve the desired

results.

Over a period of time the outlet water is slowly treated by the plants 11 and cleansed, at

which stage the treated outlet water may be removed from the facility via control shaft 14

and outlet pipes 12 and 13.

In figure 2 an example of a control shaft configuration is shown. It is assumed in this

example the solid-free liquid is passing from treatment area one via filter bed 5 and outflow

pipe 6, into control shaft 7.

A triangular shaped body 15, possibly but not necessarily constructed of a polyester

composite or the like, is positioned at the end of the filter bed for treatment area one with a

flange 16 constructed of an appropriate wastewater resistant material, such as stainless steel

or the like. Bolts are laminated into the triangular body around pipe 17, which is required to

be glued and laminated into the triangular body.

A hole of equivalent diameter to pipe 17 is cut into the foil which encases the treatment area

allowing the pipe to be passed through from the treatment area. A matching flange squeezes

a liner together with the help of the bolts to prevent leakage from the join. The pipe 17 and

the pipe 6 lead into the shaft 7 by a short piece of tube 18 attached to the shaft. Inside the shaft a piece of tube 19a, at a 90° angle, is fitted together with tube 18 in such a way that it

may be turned vertically, in order to adjust the level of the wastewater in the filter body. Into

tube 19a two other pieces 23 and 19b are installed as shown in figure 2.

In the preferred embodiment the lowest part of pipe 18 should be level with the bottom of the

filter bed 5 from which it connects. The pipe pieces 19a, 23 and 19b may be turned to adjust

the level of the wastewater in the filter. At point 20, the highest level of wastewater in the

filter may be adjusted, which is also substantially identical with the top level of the filter

body. Opposite at the very bottom of the shaft 21 is the outlet, which is installed in a similar

fashion as pipe 17. From there an inflow pipe 9 transfers the effluent into treatment area two.

A similar configuration may be used throughout the filtering and treatment installation to

control the flow of effluent and the like from one treatment area to another. This

configuration ensures a satisfactory leak-proof handling of the effluent throughout the plant.

ADVANTAGES OF THE PREFERRED EMBODIMENT

With sensible location and layout the necessity of the use of pumps in the facility may be

reduced or even excluded, allowing gravity to be the major driver of the effluent through the

facility.

If pumps are required to drive effluent through the facility, it is envisaged solar powered

pumps alone may be sufficient to achieve this due to the minimal amount of energy required

to run the facility. The water generated through the filtering process may be suitable for irrigation or for other

similar purposes. It is highly unlikely however that the water would be suitable for human

consumption or for personal hygiene uses without considerable further treatment.

There are many environmental advantages of such a system, including a reduction in the

volume of insect pests normally associated with open pond-based treatment plants such as

mosquitoes, and the ability of this system to effectively treat effluent naturally without the

need for added chemicals. Further, the use of various types of plants as part of the treatment

process may assist developing communities with the production of animal fodder and/or a

renewable supply of construction materials.

In addition, depending on site restraints, the second stage of the facility may be positioned on

a building rooftop to take advantage of the evaporation process which takes place over time

as outlet water is purified, thereby providing a cooling effect to the roof of the building, as

well as shielding the roof from the direct impact of the sun's rays. This same

evaporation/cooling process could be applied commercially where factories or the like

require a cooling process to cool their products. Alternatively the system may be positioned

on a rooftop as an insulative measure to prevent heat loss through the roof in cooler or cold

conditions.

Clearly one of the main advantages of this system is the ability to treat the solid material

from the effluent and the liquid effluent in the same facility. This is particularly useful

where effluent is generated from large scale plants, in which case the liquid effluent is often

treated at technical wastewater treatment plants while the resulting sludge has to be de- watered. This normally happens on the same premises and requires an enormous input of

energy. However, the so-called first stage of this system replaces all of the complicated

technical devices required to achieve this. These devices are expensive to purchase and to

maintain. Provided that the size and handling of the basin(s) is well set up, the solid-free

effluent from the basin may be returned into the technical plant. The resulting soil-similar

material from the "full" basin may then be composted and after marginal testing can be used

in landscaping or for whatever other applications are appropriate. If the solid material is

toxic, it could be used for covering over garbage or waster dumps which are full or almost at

capacity, or could be burned in conjunction with fossil fuel in thermal power plants.

However, one of the advantages of the present system is the sludge is able to be mineralised

and the volume reduced by up to 90% without the requirements of other inputs. Exactly the

same procedure may be used for sludge generated from a variety of other sources such as, for

example, septic tanks or other similar devices.

Claims

WHAT I CLAIM IS:

1. A multi-stage effluent treatment installation for the treatment of effluent containing

solid material comprising at least two "filtering and treatment areas", means for

supplying said effluent into a first filtering and treatment area where in use said solid

material is separated from said effluent by filtering means in said first filtering and

treatment area, means for supplying the resulting filtered fluid into a second filtering

and treatment area, leaving said solid material retained within said first filtering and

treatment area wherein said solid material is acted upon by a group of plants, and said

filtered fluid, having passed into said second filtering and treatment area and being

retained in said second filtering and treatment area is acted upon by a second group of

plants.

2. A multi-stage effluent treatment installation as claimed in claim 1, wherein said first

filtering and treatment area contains filter means comprising a plurality of individual

filter layers through which the effluent may pass, with each filter layer containing

filter material of a particular type and size.

3. A multi-stage effluent treatment installation as claimed in claim 2, wherein the said

plurality of filter layers include a final filter layer, immediately under which is a top

filter layer, a plurality of intermediate filter layers, and a bottom filter layer, with said

filter layers arranged in order depending on the size of the filter material contained in

each layer such that the bottom layer contains filter material having the greatest

diameter, the final layer contains filter material of the smallest diameter, and the inteimediate layers are arranged in order of decreasing filter material diameter from

the bottom layer to the final layer.

4. A multi-stage effluent treatment installation as claimed in claim 3, wherein the filter

material is comprised of gravel or some other type of non-reactive sub-strata.

5. A multi-stage effluent treatment installation as claimed in claim 4, wherein the final

filter layer comprises a mixture of sand and bark, or some other similar combination

of materials.

6. A multi-stage effluent treatment installation as claimed in claim 5, wherein said final

filter layer is capable of supporting a plurality of selected plants, with said final filter

layer containing organic material such as peat or bark which will provide the required

support needed for said plants to survive and prosper.

7. A multi-stage effluent treatment installation as claimed in claim 6, wherein said

plants are capable of creating root systems into the solid material extracted from the

effluent.

8. A multi-stage effluent treatment installation as claimed in claim 7, wherein said

plants are selected from predetermined genera which shows suitable characteristics

for assisting in the treatment of said solid material and the mineralisation of said solid

material extracted from the effluent.

9. A multi-stage effluent system as claimed in claim 1, wherein said second filtering and

treatment area contains filter means comprising a plurality of individual filter layers

through which the filtered fluid may pass and be retained in said second filtering and

treatment area, with each filter layer containing filter material of a particular type and

size.

10. A multi-stage effluent system as claimed in claim 9, wherein the said plurality of

filter layers include a final filter layer, immediately under which is a top filter layer, a

plurality of intermediate filter layers, and a bottom filter layer, with said filter layers

arranged in order depending on the size of the filter material contained in each layer

such that the bottom layer contains filter material having the greatest diameter, the

final layer contains filter material of the smallest diameter, and the intermediate

layers are arranged in order of decreasing filter material diameter from the bottom

layer to the final layer.

11. A multi-stage effluent treatment installation as claimed in claim 10, wherein the filter

material is comprised of gravel or some other similar type of non-reactive sub-strata.

12. A multi-stage effluent treatment installation as claimed in claim 10 or 11 , wherein the

final filter layer comprises a mixture of sand and bark, or some other similar

combination of materials.

13. A multi-stage effluent treatment installation as claimed in claim 12, wherein said final

filter layer is capable of supporting a plurality of selected plants, with said filter layer containing organic material such as peat or bark which will provide the required

support needed for said plants to survive and prosper.

14. A multi-stage effluent treatment installation as claimed in claim 13, wherein said

plants are selected predetermined genera which show suitable characteristics for

assisting in the treatment and cleansing of the filtered fluid.

15. A multi-stage effluent system as claimed in any one of the preceding claims, wherein

the second plant species are capable of releasing antibiotic secretions.

16. A multi-stage effluent system as claimed in any one of the preceding claims, wherein

both the first and second plant species are helophytic.

17. A multi-stage effluent system as claimed in any one of the preceding claims, wherein

the first filtering and treatment area is elevated above the second filtering and

treatment area, and where said effluent system comprises more than two filtering and

treatment areas, the first filtering and treatment area is elevated above the second

filtering and treatment area, with the second filtering and treatment area being

positioned above the third filtering and treatment area and so on.

18. A multi-stage effluent treatment installation as claimed in any one of the preceding

claims, wherein the size of the installation and the complexity and composition of the

filtering means included therein are determined with respect to a number of criteria,

including but not limited to the expected volume and quality of the effluent, the

expected volume .and quality of the filtered solid material, and the number of inhabitants from the town, city or the like relying on the effluent treatment

installation.

19. A multi-stage effluent treatment installation as claimed in any one of the preceding

claims, wherein means are provided which prevent the uncontrolled egress of any

effluent under treatment, or any contents of said effluent, from the filtering and

treatment areas.

20. A multi-stage effluent treatment installation as claimed in any one of the preceding

claims, wherein means are provided for controlling the ingress of the effluent and the

treated effluent, and the egress of same, and said means are sealed to prevent the

uncontrolled leaking of any effluent under treatment of any contents of said effluent

from the treatment areas.

21. A multi-stage effluent treatment installation including a first treatment zone and a

second treatment zone, means for supplying fluid effluent to said first treatment zone,

said first treatment zone comprising filtering means filtering out solids therefrom, an

outlet from the said first treatment zone for the supplying of filter fluid to said second

treatment zone, wherein the first treatment zone supports one or more first plant

species capable of utilising the solids filtered out by the filtering means, said second

treatment zone comprising a support zone for one or more second plant species

capable of producing secretions for the treatment of fluid passing through said second

treatment zone, and an outlet from said second treatment zone.

22. A method for the treatment of effluent comprising the steps of supplying fluid

effluent to a first treatment zone filtering out any solid material contained therein

from the effluent by passing said effluent through a variety of filtering means, and

then treating the solid material extracted from the effluent in said first treatment zone,

and then passing the filtered fluid out of the said first treatment zone to a second

treatment zone where further filtering may take place, followed by the treating and

cleaning of the filtered effluent in said second treatment zone, and the removal of the

treated effluent from said second treatment zone.

23. A method of filtering and cleaning effluent substantially as described herein by the

accompanying specification.

24. A multi-stage effluent treatment installation substantially as described herein by the

accompanying specification.

25. A multi-stage effluent treatment installation substantially as described herein by the

accompanying drawings.