Reducing nitrous oxide gas emissions from fill-and-draw type activated sludge process

To reduce nitrous oxide (N2O) emissions from fill-and-draw type activated sludge units treating swine wastewater, the N2O emission was compared between the continuous aeration process (conventional process) and the intermittent aeration process. About 35% of the influent nitrogen was emitted as N2O gas using the conventional process under 0.5 kg•m−3•d−1 BOD loading. About 60% of the N2O was emitted duing the first hours of aeration started just after daily charging. On the other hand, only less than 1% of the influent nitrogen was emitted as N2O gas during the intermittent aeration process.