Municipal wastewater treatment using a membrane aerated biofilm reactor

The performance of a membrane aerated biofilm reactor (MABR) treating raw municipal wastewater primary effluent was optimized. The MABR performance was challenged by the gradual increase of the organics and ammonia surface loading rates with hydraulic retention times (HRT) of 10.7, 6.24, 4.0, 2.0 and 3.0 h. With organics and ammonia surface loading rates of 20 g total chemical oxygen demand m⁻² d⁻¹ and 3.32  gNH₄ ⁺-N m⁻² d⁻¹, respectively, the reactor achieved simultaneous organics, nitrogen and total nitrogen reductions of 98, 96 and 67%, respectively. Microbial analysis indicated the coexistence of nitrite oxidizing bacteria, ammonia oxidizing bacteria, aerobic denitrifying bacteria and other bacteria within the MABR biofilm, correlating to simultaneous nitrification, denitrification and organics within the reactor. Acceptable effluent water quality was obtained when the MABR was operated at an HRT as low as 3 h.