Converting Residuals to Reuse: Taking Aeration out of Oxidation

Aeration accounts for up to 60% of the total energy required for a typical activated sludge wastewater plant. A new process was developed that decreases aeration demand during secondary wastewater treatment. This process, called BIOBROx, blends oxidant-laden residuals with screened municipal wastewater followed by treatment in a fixed-bed (FXB) bioreactor. Pilot testing showed that the BIOBROx process was effective at removing perchlorate and nitrate from membrane residuals. Considerable biochemical oxygen demand (BOD) and suspended solids were also removed across the process. A 3.8-mgd BIOBROx demonstration facility is now operating at the Magna Water District. The BIOBROx train treats 1/3 to 1/2 of Magna's total wastewater flow, uses no aeration, has an empty-bed contact time of 10 minutes, and has a footprint that is one-twentieth the size of the conventional secondary processes. Preliminary data show effluent that even under these conditions, BOD5 and TSS levels in the effluent from the BIOBROx process are similar to those in Magna's conventional secondary treatment effluent.