A divided flow aerobic-anoxic baffled reactor for simultaneous nitrification-denitrification of domestic wastewater

A novel aerobic-anoxic baffled reactor is designed for the effective denitrification of real domestic wastewater without an external carbon source. The flow is divided between two inlets at the beginning of each zone to provide a carbon source for the denitrifying bacteria. The effects of operating parameters such as the ratio of chemical oxygen demand to nitrogen (COD/N), flow division ratio, and hydraulic retention time (HRT) on the nitrogen removal were investi-gated. The optimum values of COD/N and HRT were estimated using response surface methodology (RSM) coupled with a central composite experimental design. The addition of porous biomass support media considerably improved the denitrification and removal of COD. Furthermore, the aerobic-anoxic system showed high stability against sudden HRT and COD/N ratio changes. The microbial analysis showed that Alcaligenes, Achromobacter, and Bordetella were the dominant denitrifying bacteria in the anoxic zone, whereas other species coexisted in the aerobic zone.

Automated summary

A novel reactor design was developed for efficient denitrification of domestic wastewater without external carbon source. The optimal operating parameters were determined using response surface methodology, and the addition of biomass support media improved denitrification. The aerobic-anoxic system demonstrated high stability against changes in hydraulic retention time and COD/N ratio. Microbial analysis revealed the presence of dominant denitrifying bacteria in the anoxic zone.