Shrinking the Aeration Footprint: Innovative Approaches to Nitrogen Removal in MBR Systems

A 7-month pilot investigation of the biological treatment performance of the membrane tank within a membrane bioreactor (MBR) system was conducted in Tacoma, WA. The study compared performance with and without the presence of an aeration basin upstream of the membrane tank to determine if biological reactions in the membrane tank play a significant role in the treatment process to determine if the aerated volume of the biological reactor could be further reduced. Performance of the two operating schemes was evaluated for treatment efficiency of biochemical oxygen demand (BOD), carbonaceous BOD (cBOD), and ammonia removal, while denitrification and biological phosphorus removal were also monitored. Effluent concentrations of BOD, sCOD, and ammonia were similar with and without the aeration basin, suggesting that designers of MBR facilities should account for biological processes occurring within the membrane tank when sizing MBR systems.