EPA Method 304B Determination Of Biodegradation Rates Of Organic Compounds (Scrubber Option)
ID: |
6311B3A8E2D44C32A83115105D872D3F |
文件大小(MB): |
0.05 |
页数: |
24 |
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日期: |
2000-2-12 |
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2028,METHOD 304B: DETERMINATION OF BIODEGRADATION RATES,OF ORGANIC COMPOUNDS (SCRUBBER OPTION),1.0 Scope and Application.,1.1 Applicability. This method is applicable for the,determination of biodegradation rates of organic compounds,in an activated sludge process. The test method is designed,to evaluate the ability of an aerobic biological reaction,system to degrade or destroy specific components in waste,streams. The method may also be used to determine the,effects of changes in wastewater composition on operation.,The biodegradation rates determined by utilizing this method,are not representative of a full-scale system. Full-scale,systems embody biodegradation and air emissions in competing,reactions. This method measures biodegradation in absence,of air emissions. The rates measured by this method shall,be used in conjunction with the procedures listed in,appendix C of this part to calculate the fraction emitted to,the air versus the fraction biodegraded.,2.0 Summary of Method.,2.1 A self-contained benchtop bioreactor system is,assembled in the laboratory. A sample of mixed liquor is,added and the waste stream is then fed continuously. The,benchtop bioreactor is operated under conditions nearly,identical to the target full-scale activated sludge process,except that air emissions are not a factor. The benchtop,2029,bioreactor temperature, dissolved oxygen concentration,average residence time in the reactor, waste composition,biomass concentration, and biomass composition of the target,full-scale process are the parameters which are duplicated,in the laboratory system. Biomass shall be removed from the,target full-scale activated sludge unit and held for no more,than 4 hours prior to use in the benchtop bioreactor. If,antifoaming agents are used in the full-scale system, they,shall also be used in the benchtop bioreactor. The feed,flowing into and the effluent exiting the benchtop,bioreactor are analyzed to determine the biodegradation,rates of the target compounds. The choice of analytical,methodology for measuring the compounds of interest at the,inlet and outlet to the benchtop bioreactor are left to the,discretion of the source, except where validated methods are,available.,3.0 Definitions. [Reserved],4.0 Interferences. [Reserved],5.0 Safety.,5.1 If explosive gases are produced as a byproduct of,biodegradation and could realistically pose a hazard,closely monitor headspace concentration of these gases to,ensure laboratory safety. Placement of the benchtop,2030,bioreactor system inside a laboratory hood is recommended,regardless of byproducts produced.,6.0 Equipment and Supplies.,NOTE: Figure 304B-1 illustrates a typical laboratory,apparatus used to measure biodegradation rates. While the,following description refers to Figure 304B-1, the EPA,recognizes that alternative reactor configurations, such as,alternative reactor shapes and locations of probes and the,feed inlet, will also meet the intent of this method.,Ensure that the benchtop bioreactor system is self-contained,and isolated from the atmosphere by leak-checking fittings,tubing, etc.,6.1 Benchtop Bioreactor. The biological reaction is,conducted in a biological oxidation reactor of at least,6-liters capacity. The benchtop bioreactor is sealed and,equipped with internal probes for controlling and monitoring,dissolved oxygen and internal temperature. The top of the,benchtop bioreactor is equipped for aerators, gas flow,ports, and instrumentation (while ensuring that no leaks to,the atmosphere exist around the fittings).,6.2 Aeration gas. Aeration gas is added to the,benchtop bioreactor through three diffusers, which are glass,tubes that extend to the bottom fifth of the reactor depth.,A pure oxygen pressurized cylinder is recommended in order,2031,to maintain the specified oxygen concentration. Install a,blower (e.g., Diaphragm Type, 15 SCFH capacity) to blow the,aeration gas into the benchtop bioreactor diffusers.,Measure the aeration gas flow rate with a rotameter (e.g.,0-15 SCFH recommended). The aeration gas will rise through,the benchtop bioreactor, dissolving oxygen into the mixture,in the process. The aeration gas must provide sufficient,agitation to keep the solids in suspension. Provide an exit,for the aeration gas from the top flange of the benchtop,bioreactor through a water-cooled (e.g., Allihn-type),vertical condenser. Install the condenser through a gastight,fitting in the benchtop bioreactor closure. Design,the system so that at least 10 percent of the gas flows,through an alkaline scrubber containing 175 mL of 45 percent,by weight solution of potassium hydroxide (KOH) and 5 drops,of 0.2 percent al……
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