Comparison between a single unit bioreactor and an integrated bioreactor for nutrient removal from domestic wastewater

The simultaneous nitrogen and phosphorous removal efficiency of Bacillus cereus GS-5 immobilized single unit packed bed bioreactors was compared with that of integrated bioreactors. Both the single unit and integrated bioreactors were fed with domestic wastewater (NH4+-N 70 mg/L, NO3--N 70 mg/L and PO43--P 15 mg/L) under 300-1000 mg/L carbon loading and 7.2-28.8 L/d hydraulic loading rates. The removal efficiencies of NH4+-N, NO3--N and PO43--P in the integrated bioreactor were 94.2%, 92.3%, and 97.6%, respectively, which are slightly better than the single unit bioreactor. The specific oxygen utilization rate (SOUR) showed that the integrated bioreactor (17.06 mg-O-2/g-MLSS/h) has a higher microbial activity than the single unit bioreactor (15.2 mg-O-2/g-MLSS/h). Both the single unit and integrated bioreactors successfully resisted the organic as well as hydraulic shock loading conditions. This work established promising application prospects of both single unit fixed bed and integrated bioreactor for nutrient removal from domestic wastewater.