Biomass characteristics and simultaneous nitrification-denitrification under long sludge retention time in an integrated reactor treating rural domestic sewage

▸ A novel integrated A/O biofilm reactor was proposed to treat rural domestic sewage. ▸ Sludge return and anoxic stir were needless in contrast with conventional A/O process. ▸ TN was removed efficiently by ideal SND under low C/N ratio and less sludge discharge. ▸ Wasted sludge in MBBR was disposed simply by intermittent discharge under long SRT. ▸ SRT of 42 ± 4 days promoted reduction and stabilization of aerobic biomass in MBBR.