Treatment and reuse of toilet wastewater by an airlift external circulation membrane bioreactor

Membrane bioreactor (MBR) is a high efficient technology for toilet wastewater treatment and reuse. Practical performance of a full-scale airlift external circulation membrane bioreactor (AEC-MBR) for toilet wastewater treatment was investigated. The results showed that the removals of COD, BOD5, NH4-N, color and turbidity were 90%, 99%, 95%, 80% and 99.7%, respectively, with the average effluent quality of COD 24 mg/L, BOD5 2.4 mg/L, NH4-N 5 mg/L, color 30° and turbidity 0.2 NTU. Abundant microorganisms could live well and play an important role in sludge health and in well performance of the MBR, because without circulation pump in the system. The maximum flux was maintained stably at 13.5 L/m2 on the TMP at 4–9 kPa for more than 5 months. The energy consumption of the AEC-MBR system was at 0.32–0.64 kWh m−3 and the operational cost was about $ 0.11/m3. More than 15 sets of AEC-MBR systems were applied successfully for toilet wastewater treatment and reuse in China in recent years.