A pilot study on a submerged membrane bioreactor for domestic wastewater treatment

Abstract A pilot‐scale membrane bioreactor was tested for its long‐term performance in domestic wastewater treatment. The treatment capacity was 5.5 m3/d. Over 300 days were maintained. The results demonstrated that a high‐quality effluent with COD<30 mg/L and NH3‐N<1 mg/L can be obtained. The bioreactor degraded 70% of the influent COD, while the membrane separation insured 90% of the total COD would be removed. The biomass morphology and the molecular weight distribution of the organic substances were also investigated. It was observed under a scanning electronic microscope (SEM) that sludge deposition, gel‐layer formation and microbial growth caused the membrane fouling. The membrane fouling can be under control through clear‐water washing, intensified aeration and NaClO solution in‐line cleaning.