EPA Method 304A Determination Of Biodegradation Rates Of Organic Compounds (Vent Option)
|
ID： |
EE25B01B45B5425E81CD4E85BDE1D4C4 |
|
文件大小(MB)： |
0.05 |
|
页数： |
24 |
|
文件格式： |
|
|
日期： |
2000-2-12 |
|
购买： |
文本摘录（文本识别可能有误，但文件阅览显示及打印正常，pdf文件可进行文字搜索定位）：
2004,METHOD 304A: DETERMINATION OF BIODEGRADATION RATES,OF ORGANIC COMPOUNDS (VENT 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. 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.,Bioreactor temperature, dissolved oxygen concentration,average residence time in the reactor, waste composition,biomass concentration, and biomass composition of the full,2005,scale process are the parameters which are duplicated in the,benchtop bioreactor. 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 flow rate of the exit,vent is used to calculate the concentration of target,compounds (utilizing Henry's law) in the exit gas stream.,If Henry's law constants for the compounds of interest are,not known, this method cannot be used in the determination,of the biodegradation rate and Method 304B is the suggested,method. 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,2006,ensure laboratory safety. Placement of the benchtop,bioreactor system inside a laboratory hood is recommended,regardless of byproducts produced.,6.0. Equipment and Supplies.,NOTE: Figure 304A-1 illustrates a typical laboratory,apparatus used to measure biodegradation rates. While the,following description refers to Figure 304A-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 (except for the exit vent,stream) 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,reactor 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.,2007,A pure oxygen pressurized cylinder is recommended in order,to maintain the specified oxygen concentration. Install a,blower (e.g., Diaphragm Type, 15 SCFH capacity) to blow the,aeration gas into the reactor 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. Install a,splitter which directs a portion of the gas to an exit vent,and the……
……