WO2000015563A1

WO2000015563A1 - Improved microbial biomass support structure and methods for making same

Info

Publication number: WO2000015563A1
Application number: PCT/US1999/021489
Authority: WO
Inventors: Carey Hobbs; Vidal Danilo Natividad; Glyndie Ray Brantner; Michael J. Massingill
Original assignee: Carey Hobbs; Vidal Danilo Natividad; Glyndie Ray Brantner; Massingill Michael J
Priority date: 1998-08-03
Filing date: 1999-09-17
Publication date: 2000-03-23
Also published as: AU6151199A

Abstract

The present invention is of a biomass support structure for use in waste water treatment, along with a method of manufacturing such a biomass support structure. The media of the present invention is in the form of small parcels which are fabricated of a very 'open' structure, non-woven batting material. The parcels support rapid and extensive microbial propagation and readily circulate through waste water under the effects of minimal water agitation or circulation. The biomass support structure of the present invention facilitates microbial action of accelerated, microbe-based waste water treatment programs.

Description

TITLE: IMPROVED MICROBIAL BIOMASS SUPPORT

STRUCTURE AND METHODS FOR MAKING SAME

CITATION TO PRIORAPPLICATION

This is a continuation-in-part with respect to U.S. Application, Serial No.

09/155,000, filed 17.09.98 (17 September 1998) from which priority is claimed under

35 U.S.C. §120 and under provisions of the Patent Cooperation Treaty.

BACKGROUND OF THE INVENTION

1. Field of The Invention

The present invention relates to waste water treatment and agents and

materials used in the process thereof.

2. Background Information

The conversion of ammonia (NH₃) derived from fecal material and other

biological waste to the less pernicious nitrate (NO₂) is a primary objective in

accelerated waste water treatment methodologies. This conversion occurs through the

action of microbes on the water-borne ammonia. In addition to water treatment facilities which are associated with sewage

treatment for cities, other waste water treatment programs are associated with large-

scale beef, pork, or poultry operations with waste water run-off problems as well as

with commercial fish farm operations.

In an accelerated waste water treatment program involving ammonia to nitrate

conversion through aerobic microbial action, the process of nitrification involves,

among other operative agents, two types of aerobic bacteria. Nitrosomas species

convert toxic ammonia (NH₃) into toxic nitrites (NO₂), and nitrobacter species then

convert the toxic nitrites into non-toxic nitrates (NO₃).

However, one will not achieve satisfactory, or satisfactorily rapid results if the

microbes are merely poured into the waste water in which case they will simply settle

to the bottom of the reservoir and have a very limited effect on the waste water. To

the contrary, one must foster the propagation of microbes as well as maximize

interaction of the microbes with the waste water.

The subject microbes best propagate in host environments in which the

resident colonies are protected from significant agitation and excess scouring. In view

of such considerations, practitioners of bacteria-based waste water treatment

methodologies in particular have long sought suitable biomass support structures for

microbial growth and waste water interaction.

Ideally, such a support structure will be in the form of a small, roughly golf

ball sized parcel which will be introduced by the thousands into waste water

reservoirs. Suitable biomass support structures will support microbial propagation

and will readily circulate through waste water to maximize interaction between the waste water and the resident microbes. The parcels must be sufficiently durable to

resist degradation through interaction with agitation, aeration, and water circulation

mechanisms which are common to waste water treatment systems, and ideally would

be easily cleaned (release encrusted biofilm, etc.) through the type of agitation which

is inherent to any typical waste water treatment process.

As with any environmental treatment modality, a biomass support platforms

should certainly not themselves, either directly or through its own manufacturing

process, harm the environment.

At present, there is no microbial platform (or "biomass support structure")

which supports rapid and extensive microbial propagation, readily circulates through

an aqueous medium under the effects of minimal water agitation or circulation,

exhibits a long service life, is easily cleaned of encrusted biofilm, and is

environmentally benign, both in its finished form and through its manufacturing

process. The absence of such a suitable microbial platform modality is not the

product of inaction by those involved in waste water treatment. Efforts which

preceded the present invention and were directed toward developing a suitable

biomass support structure involved the use of "foam rubber" pellets in a wide variety

of sizes, styrofoam balls, and even walnut and pistachio nut shells. Experiments with

each of these media resulted in less satisfactory results than achieved through use of

embodiments of the hereafter disclosed invention. Each of these would-be biomass

support structure exhibited very short service life lengths, failed to circulate properly

as to effect a suitable level of water/microbe interaction, and or provided insufficient

microbial propagation surfaces per unit volume. In addition, "foam rubber" and styrofoam are materials which are produced using environmentally pernicious

manufacturing processes.

In view of the foregoing, it would well serve those involved in waste water

treatment programs which utilize microbes for nitrification or denitrification processes

to have available a biomass support structure which supports rapid and extensive

microbial propagation, readily circulates through an aqueous medium under the

effects of minimal water agitation or circulation, exhibits a long service life, is easily

cleansed to biofilm encrusting, and is environmentally benign, both in its finished

form and through its manufacturing process.

In addition, providing a useful and practical biomass support structure would

serve to contain bacterial populations in a treatment vessel, thereby obviating the need

for settling/clarifying of filtering mechanisms for returning otherwise escaping

microbes to the treatment vessel.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a novel biomass support

structure for use in waste water treatment.

It is another object of the present invention to provide a biomass support

structure which supports rapid and extensive microbial propagation.

It is another object of the present invention to provide a biomass support

structure which readily circulates through an aqueous medium under the effects of

minimal water agitation or circulation.

It is another object of the present invention to provide a biomass support

structure which exhibits a long service life. It is another object of the present invention to provide a biomass support

structure which is environmentally benign, both in its finished form and through its

manufacturing process.

It is another object of the present invention to provide a biomass support

structure which supports rapid and extensive microbial propagation, readily circulates

through an aqueous medium under the effects of minimal water agitation or

circulation, exhibits a long service life, and is environmentally benign, both in its

finished form and through its manufacturing process.

It is another object of the present invention to provide a biomass support

structure which serves to contain bacterial populations in a treatment vessels, thereby

obviating the need for settling/clarifying of filtering mechanisms for returning

otherwise escaping microbes to the treatment vessel.

In satisfaction of these and related objectives, the present invention provides a

biomass support structure for use in waste water treatment and an associated method

of manufacturing the same. The media of the present invention satisfies all stated

objectives by supporting rapid and extensive microbial propagation, readily

circulating through waste water under the effects of minimal water agitation or

circulation, exhibiting a long service life, and posing no environmental hazards

through use or manufacture. Use of the biomass support structure of the present

invention facilitates superior microbial action of accelerated, bacteria-based waste

water treatment programs within acceptable cost considerations, both because of

initial acquisition costs and service life of the parcels. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of the biomass support structure of the present

invention is a small spherical object (approximately one inch in diameter) which is

formed from a non- woven batting material. The preferred batting for the present

parcels is comprised of approximately 85%) polyester fibers and approximately 15%

acrylic resin. The polyester fibers are, in turn, comprised of approximately 40% of

solid round, pentelobal and/or round hollow fibers which are between three and ten

denier. The balance of the fibers will, for the preferred embodiment, be co-polymer,

bi-component fiber or polypropylene, and in any event characterized as a low melt

polymer.

The batting used in formation of the parcels of the present invention is

manufactured through a series of steps which begins with "opening" the fiber stock.

"Opening", in the textile industry, is defined as a preliminary operation in the

processing of staple fibers which separates compressed masses of staple into loose

tufts and removes any heavier impurities (such as dirt, pieces of vegetation, etc.).

Once opened, the fibers are fed through large conduits under force of air into

the feed hopper of a card. A card is a machine used in the manufacture of staple yarns

or webs. The card separates, aligns and delivers the fibers in a sliver form to further

manufacturing equipment, and removes impurities from the fiber stock. A card

consists of a series of large cylinder-like rollers which are juxtaposed in a gear-like

arrangement, but with the rollers usually rotating in non-complimentary directions

such that the fibers therebetween are forcibly shredded and combed into desired

alignments. The mechanical action on the fibers is accomplished by action of thousands of short wires or metallic teeth which extend from the surfaces of the

various rollers.

Roller top cards, single or double doffer cards, and cards with or without

randomizing rolls can be used in manufacturing the batting for the biomass support

structures of the present invention. Thibeau cards, Hunter garnets, Proctor and

Schwartz garnets, and Hollingsworth Voss Hergeth cards, and Ta-You cards are all

candidates. However, the preferred card is exemplified by the two cylinder, single

doffer, flat wire top Hollingsworth Master Card which will be known to those skilled

in the non-woven fabrics industry.

As batting is formed by the card, a crosslapping machine lays down the webs

from the card onto a moving floor apron to form a low density batt. A crosslaping

machine ("crosslapper") lays sheets of fibrous material onto a surface in a manner

which, if onto a stationary surface, would produce a perpetually growing fan-fold like

assemblage of sheets. Because, however, the crosslapper in this case lays the webs

from the card onto a moving floor apron (basically a very large, wide conveyor), a

multi-layer sheet of fibrous webs, of substantially consistent thickness is carried along

the moving floor apron.

As the batting is carried away from the card by the moving floor apron, it

moves beneath a spray nozzle array through which is applied a binder to secure and

fortify the fibrous matrix as against later disintegration under mechanical stress or

abrasion. In the preferred mode of the present product and method of manufacture

thereof, a latex emulsion (available from Rohm & Haas under the model designation TR 407) is applied to the batting to produce a batting in which the binder constitutes

approximately 15%) of its completed weight.

The emulsion is applied from nozzles oriented at a 95° angle relative to the

planer surface of the batting. Each nozzle has an orifice diameter of > 0.0160 inches

and resides in a VJET 95015 spraying system (available from the Spraying Systems,

Inc. of Wheaton, Illinois. The nozzle arrays are adjusted to a height of between ten

and fourteen inches from the batting surface, and the emulsion is dispensed under

pressure of between fifty and sixty p.s.i.

After the batt is spray coated with latex emulsion, it then goes to a three pass

drying oven to activate and dry the latex.

The latex emulsion-treated batting is next passed through a heated nip roller to

"encrust" the batting with a cured layer of latex emulsion. The heated nip rollers are

heated to between 300°F and 450°F with a pressure on the rollers against the batting

between 60 p.s.i to 100 p.s.i.

An array of parallel "seams" are formed along the length of the batting as it

emerges from the heated nip rollers. These seams permanently compress the batting

along 1/8" to 1/16" lines with uncompressed batting extending from either side of

each seam. The seams may be formed by literal stitching (as the word "seam" might

imply), or by heat sealing, ultrasonic action, or any other method which forms a

durably compressed line along the length a batting.

Circular dies are then used to cut plugs from the batting. Each die is

positioned to cut a plug from the batting (a circular plug in the preferred embodiment

and mode of the present invention), each plug being bisected by a seam such that batting material radiates from the line of compression of the mass of batting as

effected by the seam. The resulting cut-out emerges substantially as a sphere, the size

of which is determined simply by the size of the die and the inherent limit of size

dictated by spacing of the seams. The preferred embodiment of the biomass support

structure is approximately 1 1/4 inches in diameter.

The spherical parcels which are produced as just described are used in the

treatment of waste water by introducing a number of parcels which, at least when

measured in their dry state, occupy not less than a volume of approximately 10% of

the volume of waste water to be treated.

Through action of even very slight currents in the waste water (virtually

always generated for aeration and circulation purposes in any waste water treatment

facility) the parcels of the above-described composition and manufacture are semi-

buoyant and readily undulate through the water insuring microbe/waste water

interaction as a substrate for microbes. However, the parcels are not sufficiently

buoyant (contrasted with foam rubber pellets, for example) to simply float on top of

the water, blow away in wind, and resist periodically contacting the bottom of the

waste water reservoir where intended, initial microbial "contamination" occurs and

initial microbial propagation begins.

Experiments have compared the parcels of the present invention with

alternative media as described above, and found that, among other desirable, more

beneficial characteristics, the present parcels exhibit a much longer service life than

the compared media. The other media tended, to varying, but always marked degrees,

to degrade or "erode" through interaction with reservoir walls an aeration or agitation equipment, or simply to breakdown through constant exposure to the aqueous and

chemically hostile environment. The present parcels exhibited far less degradation or

erosion.

As with any of the microbial media thus far described, the microbes which is

introduced into the waste water for ammonia conversion will form colonies in each of

the present parcels. However, the density and distribution of fibers (the "openness")

exhibited by the present parcels provides considerably enhanced surface space areas

per unit volume of parcels for microbial propagation, when compared to alternative

microbial media. Apparently as a result of fostering greater microbial propagation, as

well as the much improved undulation characteristics of the parcels, tests demonstrate

the a given volume of the present biomass support structures produce a higher level of

ammonia conversion per unit time than an equal volume of the alternative media

(foam pellets, nut shells, etc.).

The biomass support structures of the present invention are much more easily

cleansed of biofilm and other encrustations which, if not removed, render the

structures useless in the water treatment processes. Testing by the present inventors

reveal that the present biomass support structures are easily freed of contamination

(such as by biofilm encrustation) merely by the agitation which is inherent in the

aeration and other agitations which are part of any typical waste water treatment

regimen. This is in stark contrast to existing biomass support structures which, once

so contaminated, are rendered virtually useless in the waste water treatment process.

Although the invention has been described with reference to specific

embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative

embodiments of the inventions will become apparent to persons skilled in the art upon

the reference to the description of the invention. It is, therefore, contemplated that the

appended claims will cover such modifications that fall within the scope of the

invention.

Claims

We Claim:

1. A microbial biomass support structure for use in waster water

treatment, said biomass support structure being constructed of a non-woven batting

material, a portion of said batting material having seam means extending substantially

from a first exterior surface of said parcel through the thickness of said parcel to an

opposite second exterior surface of said parcel and binding layers of said batting

material together.

2. A method for producing a biomass support structure useful in waste

water treatment comprising the steps of:

selecting a piece of fibrous batting material;

imposing on said batting a seam which compresses said batting material along

the course of said seam; and

cutting from said batting a parcel across at least a portion of the breadth of

which parcel a portion of said seams extends whereby fibers of said

batting from which said parcel radiate and form the periphery of said

parcel.