Venturi Aeration, Inc. (Pelham, NH) has experienced phenomenal acceleration of desired organic reductions in sanitary wastewater using various microbial products in concert with its unique Venturi Aerator Wastewater Oxygenator technology.
At least trace amounts of specific bacteria that are capable of assimilating the organic host material in a sanitary wastestream are always present in the wastestream itself. These bacteria are present in three forms:
- Anaerobic – Capable of functioning without oxygen
- Facultative – Capable of functioning either with or without oxygen, and
- Aerobic – Capable of functioning in the presence of oxygen
Most liquid waste materials have little or no oxygen present in the sanitary collection system, therefore in their normal state, assimilation of the organic host material is performed by anaerobic bacteria and facultative bacteria operating anaerobically. The rate of their biological activity is directly proportionate to the conditions of their environment, i.e. the temperature, pH and essential nutrients available to stimulate their activity.
From our experience with various microbes, nutrients, and biological activators, we have found that although these products can stimulate bacterial activity somewhat to perform anaerobically (without oxygen) simply by dosing a media with these product(s), we have documented a significant acceleration in bioremedial performance when these products have been used in connection with dynamic oxygenation treatment equipment.
Typically, the amount of dissolved oxygen (DO) present in the liquid wastestream proportionately stimulates the level of desired bacterial activity, i.e. the more dissolved oxygen present, the greater the biological activity observed, thus the faster the desired results will be experienced. Certainly, some desired bacterial functions, such as de-nitrification, can only be performed in an anaerobic environment. However, even this bacterial activity can be accelerated by first propagating increased colonies of facultative bacteria, followed by cessation or zone separation of the aeration process causing the increased facultative colonies to perform anaerobically after uptake of the present dissolved oxygen levels.
Microbial additive products work best when the environment in which they are being applied is as compatible as possible with the “ideal” conditions necessary to sustain microbial activity. The Venturi Aerator Wastewater Oxygenator and Conditioner is capable of providing “near ideal” conditions to the liquids in which the microbes are applied.
The Venturi Aerator Wastewater Oxygenator and Conditioner, a patented device, contains no moving parts and is used for:
- Liquids pumped through the Venturi Aerator unit are saturated with massive amounts of dissolved oxygen, (by aspirating up to 7.5 mg/l of ambient oxygen into the liquid). The Venturi Aerators adds up to 2 volumes of ambient air to one volume of liquid being processed, with a ~20% SOTR (standard oxygen transfer rating).
- Stripping VOHC’s (especially residual chlorine) from the liquid to prevent degradation of the biomass.
- Stripping CO2 from the liquid to maintain optimal pH during aerobic digestion. [CO2 is a by-product of aerobic digestion, as CO2 levels in a liquid increase pH is reduced.]
- Fracturing digestible solids into macroscopic size to increase their surface area making them more readily available for digestion.
- Eliminating odors (viz. hydrogen sulfide) present in anoxic liquids by oxidation of the H2S into soluble SO4, and oxidizing –mercaptans.
- Separating emulsified fats, oils, and greases from the liquid.
- The dosing of microbes and/or nutrients into a liquid ensures their widespread distribution and uniform dispersion in the liquid being treated.
- The kinetic energy of the wastewater discharged through the Venturi Aerator Oxygenator has sufficient force to accomplish a thorough equalization and mixing of the contents of the lagoon.
The above process enhancements are all produced concurrently simply by continuous recirculation of the process wastewater through the Venturi Aerator Wastewater Oxygenator.
Facultative Sanitary Wastewater Lagoon, Syracuse, NY
In September 1996, Dick Wood, of On-Site Services, installed a multiple unit Venturi Aerator Wastewater Oxygenator and Conditioner system into an existing facultative wastewater lagoon system consisting of a two-stage treatment system, a primary lagoon (~950,000 litres) and a polishing lagoon (~400,000 litres). These two lagoons accepted the sanitary wastewater from 115 mobile home units in suburban Syracuse, NY.
Prior to the installation of the Venturi Aerator units, Mr. Wood had been treating the two lagoons with ProBiotic products for the assimilation of a 20-year sludge build-up including grease. The lagoons had been aerated with two (2) 3.7kW surface aerators (one in each lagoon). While Mr. Wood had experienced some success in prior years in controlling hydrogen sulfide odours emitted from the anaerobic bacterial activity, over time a sludge blanket began to develop in the corners of the lagoon and along its banks. The sludge blanket became so well established that there were zones of sludge that were not being treated by the surface aerators and hydrogen sulfide odours returned. These areas were not influenced by the agitation of the surface aerators, and it grew to a point where there was a defined “radius of influence” that only extended 10 feet from the center of the surface aerator.
In the Spring of 1996, Mr. Wood reported that the sludge blanket in the primary lagoon was still substantial in depth and the corners of the lagoon exhibited significant concentrations of both settled and floating sludge. Due to frequent failures of the two surface aerators (over 10 years old), the owner was unable to maintain an aerobic zone on the lagoon surface, and residents filed numerous odor complaints with the local office of the New York State Department of Environmental Conservation (DEC). The NYDEC issued a Consent Order to the owner to take immediate action to abate the odours.
In September 1996, Mr. Wood installed a multiple Venturi Aerator Oxygenator and Conditioner system consisting of:
- one (1) model VA-100 Venturi Aerator (a 6 L/s unit) for the polishing lagoon,
- one (1) model VA-250 Venturi Aerator (a 16 L/s unit) for the primary lagoon, and
- one (1) 11kW Gorman-Rupp T4 self-priming sewage pump to power both Venturi Aerator units.
These two Venturi Aerator units were installed with the pump located on the dike between the two lagoons. A suction intake line was manifolded into one suction intake line into the Gorman-Rupp pump, and the discharge was split between the two Venturi Aerator units, one in each lagoon. This configuration provided bottom to top turnover of the contents of the lagoon, pulled solids off the bottom for resuspension and digestion. Further, the kinetic energy of the Venturi Aerator was able to start spinning the “entire” sludge blanket with two hours of startup. The continued discharge from the Venturi Aerators began to break apart the spinning sludge blanket as it passed directly under the discharged liquids.
Previously when the old surface aerators failed the operator had to get into a rowboat and release the tether and pull the floating surface aerator to shore for repairs. With the Venturi Aerators located on the bank of the lagoon, this eliminated the risk of the boat flipping over during cold winter months when there was ice on the surface of the lagoon.
- Within one (1) day, the hydrogen sulfide odours being previously emitted were completely eliminated.
- Within one (1) week, the blackened, anoxic waters changed to light brown in coloration (this change in coloration is indicative of active aerobic digestive activity), and
- Within two (2) weeks, the previously reported sludge impacted corners of the primary lagoon had been decimated by the increase in aerobic bacterial activity to the point that no discernible sludge could be seen or removed from these areas.
Note: This case study was the basis for a presentation at a conference of ProBiotic Distributors and Sales Representatives held in Phoenix, Arizona delivered on January 17, 1997 by Mr. Gary Smith