Sustainable operation of submerged Anammox membrane bioreactor with recycling biogas sparging for alleviating membrane fouling

• Recycling biogas sparging is suitable for submerged Anammox MBR.
• Reactor reached an influent TN up to 1.7 g L−1 with TN removal efficiency of 83%.
• With sparging rate at 0.2 m3 h−1, the operation circle could prolong by 20 times.
• Anammox activity and membrane fouling mechanism were discussed.
• Recycling biogas sparging could reduce the cake layer formation rate.

A submerged anaerobic ammonium oxidizing (Anammox) membrane bioreactor with recycling biogas sparging for alleviating membrane fouling has been successfully operated for 100 d. Based on the batch tests, a recycling biogas sparging rate at 0.2 m3 h−1 was fixed as an ultimate value for the sustainable operation. The mixed liquor volatile suspended solid (VSS) of the inoculum for the long operation was around 3000 mg L−1. With recycling biogas sparging rate increasing stepwise from 0 to 0.2 m3 h−1, the reactor reached an influent total nitrogen (TN) up to 1.7 g L−1, a stable TN removal efficiency of 83% and a maximum specific Anammox activity (SAA) of 0.56 kg TN kg−1 VSS d−1. With recycling biogas sparging rate at 0.2 m3 h−1 (corresponding to an aeration intensity of 118 m3 m−2 h−1), the membrane operation circle could prolong by around 20 times compared to that without gas sparging. Furthermore, mechanism of membrane fouling was proposed. And with recycling biogas sparging, the VSS and EPS content increasing rate in cake layer were far less than the ones without biogas sparging. The TN removal performance and sustainable membrane operation of this system showed the appealing potential of the submerged Anammox MBR with recycling biogas sparging in treating high-strength nitrogen-containing wastewaters.