The hybrid MABR process achieves intensified nitrogen removal while N2O emissions remain low

Abstract

The hybrid membrane aerated biofilm reactor (MABR) process represents a full-scale solution for sustainable municipal wastewater treatment. However, most of the existing hybrid MABR processes retain large aerobic bioreactor volumes for nitrification, which is undesirable for energy and carbon savings. In this study, we used the plant-wide modeling approach with dynamic simulations to examine a novel hybrid MABR configuration with aeration controls that change the anoxic and aerobic fractions of the bioreactor volume. Result showed that the novel hybrid MABR showed “swinging” nitrification and denitrification capacities in response to diurnal loadings, achieving intensified nitrogen removal performance under both warm and cold temperature scenarios. N2O emissions from the hybrid MABR were only 1/5 of the emissions from the conventional activated sludge. The model predicted higher CH4 emissions from the hybrid MABR than the activated sludge process due to the methanogen growth in the oxygen-depleted MABR biofilm layer. Future measurements for CH4 emission are needed to obtain a holistic picture of the carbon footprint of the hybrid MABR process.