Biosolutions Newsletter
 

                               Vol. 4, Issue 2, December 2004

Contents

1. The Most Versatile Tool for Treatability Studies
2.  EZ-BOD Meter Great for Biotreater Monitoring

3.  Tying It All Together: Microcat-BK
 
4.  Microcat-BK-HC for Hand Cleaning

5.  Two New Feeders Ease Task of Periodic Dry MICROCAT Product Additions

6.  Bioscience at Technical Meetings

Introduction

The most complex thing about respirometry is its name. The technique is one of the simplest and most reliable ways to determine the treatability of wastewater influents to optimize wastewater treatment plant operation and to evaluate the bioremediability of soils and sludges.

ER at its most basic involves growing microorganisms in a controlled environment and then measuring the amount of oxygen they consume to quantify the growth rate. In the Bioscience 2000 Respirometer microbial growth, taking place in a sealed reactor, generates carbon dioxide, which is quantitatively absorbed. Consumption of oxygen by the microbes lowers the atmospheric pressure in the reactor, activating a level switch that turns on current to an oxygen generator. Oxygen (and waste hydrogen) are produced in the electrolysis generator by passing an electric current between electrodes immersed in a dilute acid solution.

The amount of oxygen generated to re-establish pressure equilibrium in the reactor is directly related to the amount of current consumed by electrolysis, providing an accurate and easily usable measure of microbial respiration and growth. The oxygen equivalents of the current drawn are fed directly into a computer for record keeping and analysis.

The BI-2000 respirometer is generally equipped with 8 independent reactors - expandable to 16 - which can be used simultaneously for different tests. Reactors are also available for testing soil samples or other non-liquid substrates, and for special purposes such as determining anaerobic gas production.

In a typical test, two or more reactors are charged with a microbial seed in water, including nutrients and pH adjustments. The microbial seed might be taken from a wastewater treatment plant or consist of commercially available microorganisms, such as Bioscience’s MICROCAT® products. The seed is "grown" for a period of time to establish a base line respiration rate. A sample of the influent to be tested is then added to another reactor.The oxygen consumed in the presence of influent is compared to the oxygen consumed by the control. Higher oxygen consumption indicates a biodegradable substrate. Lower oxygen consumption indicates toxicity.

In treatability tests the object is to determine, first, if the influent is treatable at all - does it kill the indigenous biomass? and second, if the sample is biodegradable, to determine how it affects the growth rate of wastewater plant biomass or selected microorganisms, such as hydrocarbon degraders. This process has been used by DuPont to screen influents to its commercial toll industrial waste treatment facility and to determine what operational changes or additions might be necessary to handle compounds that might be toxic or inhibitory to the existing biomass.

Bioscience publishes a wide variety of test protocols for use with the BI-2000. In addition to toxicity screening, as in DuPont’s program, the system is widely used for inhibition testing, determination of the general health of a treatment plant’s biomass, and quick, easy biokinetic testing. It is an excellent tool for determining product or compound biodegradability per internationally recognized test procedures (OECD).

Inhibition testing uses various concentrations of the test influent to determine the treatability of an influent stream as a function of its concentration. Some influents, treatable at one concentration, become inhibitory or toxic at higher levels, and may require diversion or step-feeding into the treatment plant. The respiration rate for the varying concentrations of test substance is determined from the oxygen uptake data collected by the respirometer and compared to the standard to determine the relative treatability of each concentration.

Short-term respirometry tests on varying concentrations of influent can be used in conjunction with soluble COD tests on the same influent to predict the anticipated reaction kinetics in the aeration basin. This information can be used to predict a system’s ability to degrade a specific waste or determine the operational parameters required to degrade it. In this procedure five different waste concentrations are tested in the respirometer. These waste concentrations are measured in terms of soluble COD. Oxygen uptake readings are used to determine the specific growth rate for the biomass subjected to the varying concentrations. Biokinetic constants are calculated from this growth rate data and the growth rates for the varying concentrations can be compared to standard models to determine normal or inhibition kinetics. The biokinetic parameters of the varying waste concentrations can also be used to help predict the required process control parameters for effective treatment of the influent.

These tests quantify the biotreatment system’s capacity to degrade the target waste. The oxygen uptake results, plus other easy-to-obtain waste degradation data, can be converted into recommendations for design, operation and management of the biotreatment or bioremediation system. The BI-2000 is widely applied for activated sludge process control, biotreatment system design, organic compound biodegradation kinetics, waste toxicity studies, and design and operation of bioremediation processes, such as slurry reactors or groundwater remediation plants.

The BI-2000 is the second generation of microbial respirometer offered by Bioscience, Inc. With a variety of bioreactors it can test biological activity in soil samples, wastes containing volatile components, and samples with very high or low BOD. It can also be used with an optional gas collection system to control and monitor anaerobic reactions.

Compared to other methods of measuring biological activity, the BI-2000 has a high degree of precision, good equilibrium of sample and gas, and continuous oxygen resupply, simulating conditions in an operating aeration basin. The amount of oxygen consumed is a direct measure of the microbial population’s ability to degrade the contaminants in a waste stream. In the BI-2000 it is displayed automatically in graphs of oxygen uptake and oxygen uptake rate vs. time.

While the BI-2000 is excellent for bench testing and longer biodegradation studies, the EZ-BOD meter is a single-reactor respirometer that is portable and easy for wastewater plant operators and technicians to use. The small, portable EZ-BOD meter from Bioscience has everything you need to operate a biotreater efficiently in a single package. It will monitor the system rapidly, diagnose operating problems and evaluate influent waste streams for toxicity

The EZ-BOD meter utilizes measurements of dissolved oxygen (DO) and specific oxygen uptake rate in a stirred and aerated reaction vessel. To evaluate toxicity, the self-contained reactor is filled with the wastewater to be evaluated and seeded with sludge from the biotreater. Continuous DO measurements feed into an on-board computer programmed to convert the readings to oxygen uptake rate. Accurate toxicity readings can be obtained in as little as 15 minutes, so that toxic or inhibitory waste streams can be diverted.

The meter, which weighs just 25 pounds, includes a membrane keypad, LCD screen readout, printer, aeration pump and DC stir motor. Other built-in programs enable the operator to evaluate treatment plant biomass activity in as little as 5 minutes, and to accurately predict five-day BOD readings of samples in 30 to 60 minutes. Information from the EZ-BOD can be stored on a disk or downloaded to a PC for a permanent record.

For further information call 1-800-627-3069, FAX 610-691-2170, or visit our web site at www.bioscienceinc.com.

Chemical compounds for vehicle washing or parts cleaning– solvents, detergents, or surfactants, or a combination thereof-- are usually chosen for their effectiveness in a particular application. Although consideration is also given to safety and handling of vapors, there has been little attention to the problem of disposing of wastewater from cleaning procedures. It may be collected and sent to a disposal facility, which can be quite expensive, or flushed down the drain, often with entrained hydrocarbons that can adversely affect sewer lines, lift stations or wastewater treatment plants downstream. This is particularly true of solvent-based cleaners, redeposit grease on any downstream obstruction.

Bioscience has developed a two-part approach to the problem: Microcat-BK-A Degreaser and Microcat-BK-B Biodegrader. Microcat-BK-A is a citrus-based degreaser and cleaning agent proven effective during several years of application in U.S. oilfields. It has been used in waste pits to solubilize crude oil deposits so that they can be biodegraded. Unlike many cleaning products, Microcat-BK-A itself is pH neutral and readily biodegradable.

Microcat BK-B is a blend of naturally occurring microorganisms and growth accelerators specially selected and adapted for rapid degradation of both Microcat-BK-A and those hydrocarbons and other soils it has removed. The water-based Microcat-BK-A emulsion acts as a medium for biological degradation, right in the wastewater runoff storage tank. The only other requirement for conversion of hydrocarbons into cell protein, carbon dioxide and water is oxygen, which can be supplied by a simple aerator.

The result of the two part system, custom designed by Bioscience for each application, is wastewater that can meet local, state and federal guidelines for disposal in municipal sewage lines, without the danger of downstream deposits, and the elimination of high disposal fees for hazardous wastes, such as solvent residues.

Microcat-BK-A is such an effective cleaner that those who have experienced it would use the product even if it were not biodegradable. That it also saves money on water makeup costs and ultimate disposal costs, while solving a possible community relations problem, makes it an ideal solution to a variety of tough cleaning problems in the equipment rebuilding, vehicle washing and metalworking industries

As described above, Microcat-BK-A, a degreasing formulation based on naturally occurring plant extracts,, has proven highly effective for vehicle washing, parts degreasing and other heavy-duty industrial cleaning procedures. It is safe for plants and people, non-corrosive and non-caustic, and when combined with the bacterial product, Microcat-BK-B, rapidly degrades hydrocarbons in wash water to harmless proteins and fatty acids, reducing or eliminating wastewater disposal costs and overloading of wastewater processing facilities.

Now the same type of product is available in a milder formulation for hand cleaning, to replace skin-drying detergents, abrasives and synthetic surfactants. Called Microcat-BK-HC, the new product is effective on all kinds of oily grime, works faster than other commercial hand cleaners and will not irritate skin. Rinse water can be biodegraded in the same systems used for parts cleaning or pressure washing wastewater.

For further information, call Bioscience, Inc. at 610-974-9693, or e-mail us at bioscience@bioscienceinc.com.

For most effective application, MICROCAT biological products must be applied regularly to systems such as wastewater treatment plants, sewer lines, lift stations and grease traps. Bioscience now offers dry feeders that dispense precise amounts of product at pre-determined times, saving time and money while eliminating waste.

The larger feeder will hold an average one-month supply of dry product for use in large lift stations or medium-sized wastewater treatment plants. It automatically meters up to 6 kg per day of dry product, hydrates it, and adds the mixture to the system. The feeder is available for sale or lease.

A smaller unit operates on the same principle but at lower cost. It has a hopper capacity of 15 pounds and is intended for large grease traps or small wastewater treatment plants.

For further information, call Bioscience, Inc. at 610-974-9693, or e-mail us at bioscience@bioscienceinc.com.

Bioscience president Thomas G. Zitrides recently took part in a seminar for the Technical Association of the Pulp and Paper Industry (TAPPI) in Atlanta. The program addressed the subject of bioaugmentation in the treatment of paper mill wastewater.

The company exhibited biological products and analytical instruments at Booth 2647 at the Water Environment Federation WEFTEC conference in New Orleans, Oct. 3-6.

Cold weather is already settling on northern climes. If you expect problems with ammonia removal through the winter, now is the time to start adding small amounts of nitrifiers (MICROCAT-XNL or XNC) to your wastewater treatment systems. It is much more difficult – and more expensive– to recover once you have lost nitrification and it is very cold! Contact us for a custom-tailored application program for your plant.

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