Optimization of a nitrite-dependent anaerobic methane oxidation (n-damo) process by enhancing methane availability

The nitrite-dependent anaerobic methane oxidation (n-damo) process is believed to have good application prospects, but its development is limited by the low growth rate and low specific activity of n-damo bacteria. In this study, immobilized biologically activated carbon (IC) and high static pressure (HP) were investigated to improve the performance of the n-damo process by enhancing methane availability. Both IC and HP improved the activity of n-damo bacteria, and the highest n-damo specific activity was obtained in the HP-IC system, which reached 47.65 +/- 0.21 mu mol N L-1 g(-1) h(-1). The larger specific surface area of biomass in the HP system was conducive to the transfer of methane, whereas IC increased the methane absorption capacity by approximately 10-fold and facilitated the methane supply to n-damo bacteria. Furthermore, q-PCR analysis revealed that both HP and IC improved the growth rate of n-damo bacteria, while HP could also enrich the diversity of n-damo bacteria.