Methanotrophs and Methanogens for Pollution Control: PCE, TCE Removal fromGroundwater and Macro Nutrient Removals from Wastewater, Annual Report, April 1, 1989-March 31, 1990

摘要

The study is the second phase of a large effort to utilize aerobic bacteria thatuse methane gas as an energy source to degrade toxics often found in contaminated groundwater. The focus of the effort was on the attached microbial film expanded bed reactor as a bioreactor that would accumulate large concentrations of bacteria. During the past year, most experiments included continuously flowing bioreactor parametric definition at 35 C with trichloroethylene. Earlier work had defined good potential for the methanotrophic attached film expanded bed (MAFEB) for establishing high microbial concentrations that would enable high flow rate treatment of water. It was found that the maximum specific substrate removal rate was 0.54 mgTCE/gVS-d and the half rate coefficients, K(sub s), was 3.7 mgTCE/L. These values were similar for batch and continuous operations with slightly lower K(sub s) values determined for the continuous operations. The relatively high value of K(sub s) indicates that the methanotrophic system has some difficulty rapidly degrading TCE. For this reason, an anaerobic first stage system was considered. This was tested and found to be feasible with the degradation rates greater than 100 times that of the methanotrophic system. The disadvantage of the AAFEB using the methanogenic system was that the final product was vinyl chloride. This was found to be rapidly degraded by the MAFEB step.