Biomethane by psychrophilic methanogenic community isolated from sediment of Crane Lake in Zhalong wetland, Northeast China

The performance of anaerobic digesters was inhibited intensively by low temperature anaerobic digestion. In this study, a group of psychrophilic methanogenic community was isolated from psychrophilic environment, sediment of Crane Lake. The massively parallel sequencing technology, 454 pyrosequencing technique, was adopted to analyze bacterial community, with dominant phyla belonging to Firmicutes (78.64% of total bacteria), Bacteroidetes (7.97%) and Chloroflexi (3.91%). Methanobacteria sp. and Methanomicrobia sp. were detected by clone library technique. After 6 enrichment culture generations, cumulative biogas production and methane concentration achieved 195 ml and 57.4%, respectively. The optimum performance of enrichment psychrophiles exhibited at a temperature of 18 °C, and maximum voluminal biogas production was 0.26 m³ m³ _reactor d^-1. The study also investigated the biomethane conversion of enrichment psychrophiles utilizing acidified cattle dung as substrate. After 11 days of operation, the maximum biogas production and methane concentration achieved 48 ml d^-1 and 51.6%, respectively.