Low energy single-staged anaerobic fluidized bed ceramic membrane bioreactor (AFCMBR) for wastewater treatment

•Ceramic membrane was applied in anaerobic fluidized MBR for low-strength wastewater.•Membrane net flux of 17 LMH was achieved with only periodic maintenance cleaning.•No adverse effect of the maintenance cleaning on organic removal was observed.•Average SCOD in membrane permeate of 23 mg/L was achieved.•Electrical energy required to operate the AFCMBR was only about 0.038 kWh/m3.

An aluminum dioxide (Al2O3) ceramic membrane was used in a single-stage anaerobic fluidized bed ceramic membrane bioreactor (AFCMBR) for low-strength wastewater treatment. The AFCMBR was operated continuously for 395 days at 25 °C using a synthetic wastewater having a chemical oxygen demand (COD) averaging 260 mg/L. A membrane net flux as high as 14.5-17 L/m2 h was achieved with only periodic maintenance cleaning, obtained by adding 25 mg/L of sodium hypochlorite solution. No adverse effect of the maintenance cleaning on organic removal was observed. An average SCOD in the membrane permeate of 23 mg/L was achieved with a 1 h hydraulic retention time (HRT). Biosolids production averaged 0.014 ± 0.007 gVSS/gCOD removed. The estimated electrical energy required to operate the AFCMBR system was 0.039 kWh/m3, which is only about 17% of the electrical energy that could be generated with the methane produced.