Nitrate/nitrite dependent anaerobic methane oxidation coupling with anammox in membrane biotrickling filter for nitrogen removal

Combining nitrate/nitrite dependent anaerobic methane oxidation (n-DAMO) and anaerobic ammonium oxidation (Anammox) is a promising sustainable wastewater treatment technology, which simultaneously achieve nitrogen removal and methane emission mitigation. However, the practical application of n-DAMO has been greatly limited by its extremely slow growth-rate and low reaction rate. This work proposes an innovative Membrane BioTrickling Filter (MBTF), which consist of hollow fiber membrane for effective methane supplementation and polyurethane sponge as support media for the attachment and growth of biofilm coupling n-DAMO with Anammox. When steady state with a hydraulic retention time (HRT) of 6.00 h was reached, above 99.9% of nitrogen was removed from synthetic sidestream wastewater at a rate of 3.99 g N L⁻¹ d⁻¹. This system presented robust capacity to withstand unstable partial nitritation effluent, achieving complete nitrogen removal at a varied nitrite to ammonium ratio in the range of 1.10–1.40. It is confirmed that n-DAMO and Anammox microorganisms jointly dominated the microbial community by pyrosequencing technology. The complete nitrogen removal potential at high-rate and efficient biomass retention (12.4 g VSS L⁻¹) of MBTF offers promising alternative for sustainable wastewater treatment by the combination of n-DAMO and Anammox.