Anaerobic oxidation of methane coupled to denitrification (AOM-D) is a unique microbial process which can oxidize methane coupled with nitrate reduction. This process can be a promising biotechnology for nitrogen treatment since nitrate can be reduced using methane produced from anaerobic digestion without additional carbon source requirement.AOM-D could occur in two ways. The first AOM-D that has been proposed is based on methane oxidation/denitrification by methanotrophs or syntrophic reaction between methanotrophs and denitrifying bacteria. The second AOM-D that has been proposed, is based on syntrophic reaction between reverse methanogenesis by anaerobic methanotrophic (ANME) archaea (or methanogen-like archaea) and denitrification by bacteria.
In terms of engineering application, our group has been operating a membrane biofilm reactor(MBfR)for denitrification, as shown in the figure below. CH4 and nitrate are supplied as an electron donor and electron acceptor, respectively.CH4 gas is delivered through the inside the poreless hollow fiber membrane to a biofilm that naturally accumulates on the outer surface of bubbleless membranes. Furthermore, both methane oxidation and nitrate reduction that occurs in the biofilm is facilitated by denitrifying methanotrophs.
Current research is focused on the AMO-D kinetics in a series of batch experiments, in addition to the operation of the MBfR, investigating the optimum operating conditions and substrate limitation impact on the nitrate/nitrite removal efficiency.