Performance of anaerobic forward osmosis membrane bioreactor (AnOMBR) for dissolved gases transfer and energy recovery

Abstract

This paper focuses on the properties and mechanism of dissolved gases permeate membrane and energy recovery efficiency in the anaerobic forward osmosis membrane bioreactor under different membranes types (CTA-ES and CTA-NW), membrane orientations, temperatures (25 °C and 35 °C) and influent COD concentrations (3000 mg/L,6000 mg/L and 9000 mg/L). CTA membrane allowed the permeation of dissolved H2, and the concentration of dissolved H2 in the draw side (between 2.4 mg/L and 4.2 mg/L) was higher than the feed side (between 1 mg/L and 3.4 mg/L). This was beneficial to the anaerobic digestion because the partial pressure of H2 in the reactor was reduced. A small amount of dissolved CO2 (around 7 mg/L in draw side while between 56 mg/L and 256 mg/L in feed side) was allowed to pass through the CTA membrane. CTA membrane nearly 100% blocks the permeation of dissolved CH4 at different operation conditions in this paper. The highest methane yield was 0.256 L CH4/g COD at 35 °C with the influent COD was 6000 mg/L. This showed that AnOMBR could solve the problem of effluent containing dissolved methane in conventional anaerobic treatment, and had great potential in energy recovery.