Membrane reciprocation as energy-efficient fouling control with high biogas recovery in a pilot-scale anaerobic membrane bioreactor

•First pilot-scale AnMBR employing membrane reciprocation for fouling control.•Membrane reciprocation consumed 62% less energy than biogas sparging.•Up to 88% generated methane recovered in biogas, with the rest in dissolved phase.•Positive net energy balance is possible in AnMBR with membrane reciprocation. Anaerobic membrane bioreactor (AnMBR) as a primary treatment has the benefit of energy recovery through biogas generation. However, high energy consumption for fouling control remains the bottleneck for its applications. To this end, this study investigated the energy outlook of using membrane reciprocation as fouling control method in a pilot-scale AnMBR treating domestic wastewater, as compared to using conventional biogas sparging. The carbon balance calculation was conducted during the AnMBR operation to identify the methane conversion from organic carbon, setting the basis for energy evaluation. Both fouling control strategies were investigated under different biogas sparging speeds and membrane reciprocation frequencies. Critical flux tests and energy calculations have shown membrane reciprocation to consume 0.59 kWh/m3 at 7 L/m2/h (LMH), 62% less energy contrasting biogas sparging (1.56 kWh/m3 at 6 LMH). With the high biogas recovery and energy-efficient fouling control, positive net energy balance (0.55–0.74 kWh/m3) was achieved in this AnMBR, highlighting the potential of AnMBR with membrane reciprocation as an energy-positive A-stage in domestic sewage treatment. [Display omitted]