OXYGEN — NATURE’S CATALYST FOR ENHANCED BIO-REMEDIATION
by: Gary L. Smith
President, Venturi Aeration, Inc.
[Note: This paper was the basis for a presentation at a conference of Manufacturers, Distributors and Sales Representatives of various microbial products in Phoenix, Arozona delivered on January 17, 1997]
Venturi Aeration, Inc. (Pelham, NH) has experienced phenomenal acceleration of desired remedial results using various microbial microorganisms in connection with Venturi Aeration’s Oxygenator technology.
At least trace amounts of specific bacteria that are capable of assimilating the host material are always present. The 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, therefore in the normal state, assimilation of the 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 using microbes, nutrients, and various activators, we have found that although these products can stimulate bacterial activity somewhat to perform anaerobically (without oxygen) simply by dosing a media with the product(s), we have documented a significant acceleration in bioremedial performance when these products have been used in concert 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.
BioCatalytic products 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 Oxygenator and Conditioner is capable of providing “near ideal” conditions to the liquids in which the microbes are applied.
The Venturi Oxygenator and Conditioner contains no moving parts and is used for:
- Saturating a liquid being pumped through the unit with massive amounts of dissolved oxygen, (by aspirating up to 7.5 mg/l of ambient oxygen into the liquid).
- 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 depressed.]
- 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 to insure their widespread distribution in the liquid being treated.
The above process enhancements are all produced concurrently simply by re-circulating the process liquid or waststream through the Venturi Oxygenator.
I: Syracuse, NY Facultative Lagoon Project
In September 1996, Dick Wood, On-Site Servcies, installed a multiple Venturi Aerator Wastewater Oxygenator and Conditioner system in an existing facultative wastewater lagoon system consisting of a primary lagoon and a polishing lagoon. Prior to the installation, Mr. Wood had been treating the two lagoons with both seed microorganisms and micronutrients for the assimilation of a 20 year sludge build-up. The lagoons had previously been aerated with two (2) 3.7kW surface aerators (one in each lagoon) and Mr. Wood had experienced some success in prior years in the control of hydrogen sulfide odors emitted from the anaerobic bacterial activity.
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 old surface aerator, the owner was unable to maintain an aerobic zone on the lagoon surface, and residents filed odor complaints with the New York State Department of Environmental Conservation (DEC).
In September, 1996, Mr. Wood purchased and 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 Venturi Aeration Pump (Gorman-Rupp T4) system to power both units.
- Within one (1) day, the hydrogen sulfide odors being previously emitted were 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.
II. Field Project: Industrial Leachfield Remediation, Massachusetts
An industrial client of Venturi Aeration’s experienced a “total failure” of its leachfield system in the summer of 1995. Unfortunately, the leachfield system had been the recipient of both organic waste materials and discharges of industrial waste which contained petroleum hydrocarbon oils and grease, and various dissolved metals (copper, nickel, zinc, bronze alloy, and magnesium). The leachfield was situated directly under the parking lot of the facility and was the sole source of discharge of the plant’s wastewater. The leachfield was approximately ten (10) years old.
The failure resulted in the almost daily pumping of the septage tank to prevent ground overflow in the parking lot from the adjacent distribution box. Estimates of replacement costs of the leachfield averaged $ 300,000.00.
In October 1995, Venturi Aeration, Inc. was contracted to solve the problem. First, Venturi Aeration personnel installed equipment inside the facility to recycle their industrial wastewater and to prevent further contamination of the leachfield by industrial wastewater [zero discharge system]. Secondly, a leachfield oxygenation and conditioning system was designed to pump activated and acclimated bacteria and nutrients into the leachfield to clear the plugged leachfield.
A consortium of bacertia and micronutrients were used with the treatment and dosage equipment was set up to continually dose the failed field (throughout the piping system) by adding the consortia into the distribution box. This was performed after first treating the field with metals sequestering agents to prevent damage to the working biomass and it was accomplished during the very cold New England winter months of 1995-96.
- Within three (3) weeks, the leachfield was partially opened to the point that no additional daily septage pumping was necessary.
- Within twelve (12) weeks, the percolation rate of the leachfield had increased to the State’s leachfield performance specifications [310 CMR 15.00, Title 5 State Environmental Code] and the on-site treatment equipment was removed at the end of 16 weeks..
- Since the winter of 1995, no overflows of the leachfield system have occurred.
- The leachfield was inspected in December 1996 and was found to be completely within Title 5 code requirements and hydraulically functioning as designed.
The above case studies are but two examples of enhancing the performance of the various microbial products when used in concert with the “venturi-aeration” Oxygenation system.