[Acclimatization and Community Structure Analysis of the Microbial Consortium in Nitrate-Dependent Anaerobic Methane...

Methane oxidation coupled with denitrification is an effective way to reduce the discharge of nitrate and methane. The anaerobic sludge from a laboratory wastewater treatment facility, anaerobic sludge from a wastewater treatment plant, and soil from a landfill were selected as inoculum to enrich the consortium for anaerobic methane oxidation in cooperation with nitrate reduction. The investigation of methane oxidation was carried out in these systems. The results showed that the maximum methane consumption rate of 0.05 mg·d^-1 was obtained when the anaerobic sludge from a wastewater treatment plant served as inoculum. The population of bacteria and archaea were assayed by the clone library method. The Methanosarcinales and Methanomicrobiales were present in methane oxidation as methane oxidizing archea. The Pseudomonas, Clostridia, and Thermomonas were identified as nitrate reducing bacteria in the process of nitrate reduction. Both the methane conversion rate and microbial population varied with the amount of nitrate. The nitrate reduction bacteria were Pseudomonas and Clostridia when the nitrate concentration was 200 mg·L^-1. The Pseudomonas and Thermomonas emerged when the nitrate concentration increased to 500 mg·L^-1, and the rate of methane conversion was increased by 34.7%. The results provided science evidence for the co-treatment of methane and nitrate.