Development of anaerobic osmotic membrane bioreactor for low-strength wastewater treatment at mesophilic condition

Abstract A novel anaerobic osmotic membrane bioreactor (AnOMBR) was developed for treating low-strength wastewater. The AnOMBR utilizes a forward osmosis (FO) membrane to retain influent organic waste, which facilitates anaerobic wastewater treatment and energy recovery in the form of methane gas. The feasibility of AnOMBR for treating low-strength wastewater at mesophilic temperature was evaluated and membrane fouling was investigated. Permeate flux declined under the combined effects of both salt accumulation and membrane fouling. Although flux reduction was dominated by the effect of salt accumulation in the reactor, the presence of organic fouling and inorganic scaling could be clearly identified. Bulk pH could be maintained within neutral to slightly alkaline due to the retention of alkalinity by the FO membrane. The AnOMBR shows good and stable removal of soluble chemical oxygen demand (sCOD) and nearly complete removal of total phosphorous. However, only partial removal of total nitrogen and ammonia was observed. The elevated salt environment appeared to have little effect on bioactivity of methanogens, and stable methane production of 0.3 L/g sCOD digested was obtained.