United States Environmental Protection Agency EPA/540/F-93/506 July 1993 vvEPA SUPERFUND INNOVATIVE TECHNOLOGY EVALUATION Emerging Technology Bulletin Methanotrophic Bioreactor System BiotroP, Inc. Technology Description: BioTrol's Methanotrophic Bioreactor is an above-ground remedial system for water contaminated with halogenated volatile organic compounds, including trichloroethyl- ene (ICE) and related chemicals. Its design features circumvent problems peculiar to treatment of this unique class of chemicals. First, microorganisms are not known which utilize these chemi- cals as a primary carbon source; so a specific organism (Methylosinus trichosporium OB3b, or simply OB3b) is used which oxidizes these compounds rapidly while utilizing methane, an abundant and inexpensive source of carbon, as its growth sub- strate. Second, because of the ability of the bacterium to degrade ICE in the absence of the growth substrate, growth of the organism and degradation of the contaminants can take place in separate reactor vessels. This is important because these con- taminants are extremely volatile, and bubbling of methane or air through the reaction vessel would likely result in stripping of the contaminants from the water. A two-stage bioreactor system (diagramed in Figure 1) was designed which circumvents these problems. The first stage involves the propagation of OB3b on methane in a continuous- flow suspended growth reactor (culture vessel). Cells grown in the culture vessel are supplied to the second stage (plug flow) contactor where the culture medium is mixed with the contami- nated water. For the pilot demonstration, the culture vessel consisted of a 400- L fermenter which was modified to permit continuous-flow fer- mentation and the use of methane as the growth substrate. Methane transfer efficiency to the culture vessel was improved by addition of a circulating gas-saturation device. The plug flow Ground Water IPlug Flow Contactor v Effluent Figure 1. Bioreactor system flow diagram. Printed on Recycled Paper ------- United States Environmental Protection Agency EPA/540/F-93/506 July 1993 v>EPA SUPERFUND INNOVATIVE TECHNOLOGY EVALUATION Emerging Technology Bulletin Methanotrophic Bioreactor System BiotroP, Inc. Technology Description: BioTrol's Methanotrophic Bioreactor is an above-ground remedial system for water contaminated with halogenated volatile organic compounds, including trichloroethyl- ene (ICE) and related chemicals. Its design features circumvent problems peculiar to treatment of this unique class of chemicals. First, microorganisms are not known which utilize these chemi- cals as a primary carbon source; so a specific organism (Methylosinus trichosporium OB3b, or simply OB3b) is used which oxidizes these compounds rapidly while utilizing methane, an abundant and inexpensive source of carbon, as its growth sub- strate. Second, because of the ability of the bacterium to degrade ICE in the absence of the growth substrate, growth of the organism and degradation of the contaminants can take place in separate reactor vessels. This is important because these con- taminants are extremely volatile, and bubbling of methane or air through the reaction vessel would likely result in stripping of the contaminants from the water. A two-stage bioreactor system (diagramed in Figure 1) was designed which circumvents these problems. The first stage involves the propagation of OB3b on methane in a continuous- flow suspended growth reactor (culture vessel). Cells grown in the culture vessel are supplied to the second stage (plug flow) contactor where the culture medium is mixed with the contami- nated water. For the pilot demonstration, the culture vessel consisted of a 400- L fermenter which was modified to permit continuous-flow fer- mentation and the use of methane as the growth substrate. Methane transfer efficiency to the culture vessel was improved by addition of a circulating gas-saturation device. The plug flow IPlug Flow Contactor v Effluent Figure 1. Bioreactor system flow diagram. Printed on Recycled Paper ------- |