Management of dissolved methane from anaerobic effluents

Anaerobic digesters in wastewater treatment plants discharge dissolved methane, which usually stripped off to the environment on subsequent handling leading to GHG emission and loss of an energy source. To prevent the emission of methane gas, we utilized a packed bed column as a post-treatment biological process. The packing in the column is enriched with methane-oxidizing bacteria which oxidizes methane in aerobic conditions to CO2. At 37˚C, the average methane oxidation rate was 0.38 Kg COD/m3/d at a residence time of 1d. Further, on decreasing the residence time to 2 h the average methane oxidation rate was 0.98 Kg COD/m3/d indicating maximum activity of methanotrophs occurs in the first 2 h. Two methods were employed to measure dissolved methane in the samples, and they were very well correlated with an R-value of 0.93. PCR results indicate that pmoA gene responsible for methane oxidation is present in the enriched bacteria.