Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
2000-12-28
2004-08-03
Prince, Fred (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
C210S615000, C210S630000, C210S150000
Reexamination Certificate
active
06770198
ABSTRACT:
FIELD OF INVENTION
This invention relates to a method of treating waste water. The invention has particular application to the treatment of waste water where there is a relatively long period before the waste water is discharged. This invention has particular but not exclusive application to the treatment of sewerage effluent and for illustrative purposes only reference will be made to this application.
PRIOR ART
The conventional method of treating sewerage is transferring sewerage effluent through a network of sewerage mains and pumping stations to a sewerage treatment plant at or close to the site where the treated effluent will be released. At the conventional sewerage treatment plants, the sewerage effluent undergoes a series of anaerobic and aerobic incubations to remove waste including organic matter, other solids, nitrogen and phosphate and disinfection to reduce the number of pathogenic organisms in the sewerage effluent prior to its release.
As the sewerage effluent passes through the sewerage mains and pumping stations, the sewerage effluent becomes an incubating culture with the production of a variety of fermentation products including hydrogen sulphide and ammonia. The composition of the sewerage effluent is continuously changing during its passage. The noxious and aggressive atmospheres produced in the sewerage mains and sewerage treatment plants damages the mains pipe and pumping and plant equipment which as a result require regular maintenance.
At the sewerage treatment plant the fermentation products and greater numbers of undesirable microorganisms cause further problems including foaming of aerated tanks in sewerage treatment plants as a result of the proliferation of filamentous bacteria incubating in a nutrient rich environment. The foaming problem in aerobic tanks results in the need for additional treatment and extends the time for treatment before the treated sewerage effluent can be released. These problems cause the cost of treatment to rise.
SUMMARY OF THE INVENTION
The current invention was developed from the concept of using rising mains, gravity mains and various pumping wells as effective anaerobic and aerobic incubators using cultures of selected microorganisms. That is, the current invention uses the time and space provided by the collection and transfer system to effectively treat the sewerage effluent before it reaches the sewerage treatment plant. The inoculation with selected microorganism cultures results in competition for available nutrients and thus alters the type and number of microorganisms and the type and quantity of fermentation products produced in the sewerage effluent.
The invention in one aspect broadly resides in a method of treating waste water in a waste water reticulation system including
inoculating the waste water with an inoculum of selected microorganisms at a site prior to the treatment plant in the waste water reticulation system or discharge site where there is no treatment plant in the waste water reticulation system; and
incubating the waste water inoculated with the selected microorganisms to form a culture that reduces waste in the inoculated waste water.
In one preferred form the site of inoculation to the waste water is as close as possible to the site of entry of the waste. In another form the site of inoculation is a site through which flows between 25% and 75% of the volume of the waste water in the reticulation system.
In another aspect, the current invention broadly resides in a method of treating waste water in a waste water reticulation system including:
inoculating the waste water with an inoculum of selected microorganisms at a site through which flows between 25% and 75% of the volume of the waste water in the reticulation system; and
incubating the waste water inoculated with the selected microorganisms to form a culture that reduces waste in the inoculated waste water.
Preferably the inoculum of selected microorganisms is inoculated into the waste water at a site through which flows approximately 50% of the volume of the waste water in the reticulation system.
Preferably the inoculation site occurs within the first 25% of time or distance to the treatment plant.
Inoculation preferably occurs by inoculation means which may include spraying of inoculum from a nozzle or passing waste water over a support medium seeded with selected microorganisms. Inoculation may occur in existing sewerage mains, pump wells, silt collection traps and transfer stations. In addition, the surface area in the collection and transfer network provides potential sites for support mediums of inoculating microorganisms. Inoculation means may include inoculation chambers as described below.
The inoculation means employed at a particular site will depend on the conditions at the site. For example, where the level of anaerobic activity will be high because of long rising mains or long retention time due to slow flow, aerosol inoculation is preferred as it allows proliferation of augmented aerobic organisms in the effluent to help maintain a balance of aerobic and anaerobic activity and this is particularly relevant where the inoculum contains organisms which allow an increased level of dissolved oxygen to appear in the effluent during anaerobic activity. In another example where there are long gravity mains and there will be relatively high aerobic activity, a support medium of seeded selected microorganisms are positioned so that effluent passing over is inoculated with the microorganisms. This allows proliferation of augmented anaerobic organisms in the effluent to help maintain a balance of aerobic and anaerobic activity allowing some increased anaerobic activity in a largely aerobic environment.
The inoculum of selected microorganisms preferably is a mixed population of microorganisms. The inoculum of selected microorganisms preferably includes anaerobic and aerobic microorganisms. The inoculum of selected microorganisms is preferably a mixed population where the proportions of which may vary depending on the type of waste introduced into the waste water reticulation system. Further, the type of microorganisms selected may vary depending on the type of waste introduced into the waste water reticulation system. For example, where the waste introduced into the waste water reticulation system has a high proportion of fat or oil, lactic acid bacteria may be selected and an inoculum may contain a high proportion of lactic acid bacteria compared with other microorganisms. In creating the conditions where an inoculum contains a high proportion of lactic acid bacteria a relatively large amount of sugar may be added to serve as a substrate for lactic acid bacteria and other organisms which as a consequence forms acetic acid that assists in degrading the fat and oil substrates.
The selected microorganisms may include heterotrophic bacteria such as purple non-sulphur producing heterotrophic photosynthetic bacteria,
lactobacillus
, yeasts,
actinomycetes, Nocardia
species, ray fungi,
Bacillus
species, plankton and other synergistic microorganisms and chemoautotrophic bacteria. A preferred source of microorganisms is the commercially produced EM (“Effective Microorganisms”) formulations.
Inoculum of selected microorganisms may be prepared as a batch culture or is prepared from a continuous culture.
The selected microorganisms are preferably chosen because of their ability to cooperate in reducing the waste to small molecular weight products, water and CO
2
. The microorganisms are preferably chosen based on their ability to breakdown each others products.
The incubated inoculated effluent in the inoculation chambers allows the selected microorganisms to adapt to and reproduce in the effluent as a medium source. This reduces the environmental shock on the selected microorganisms when they are released to the retriculation system. In pump well inoculation chambers the subsequent culture incubates until a sensor signals for the release of the culture into the mains. In in-line inoculation chambers the subsequent culture constantly incub
Bellamy Kenneth Michael
Newton Robert Kingsley
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