Membrane Contactors for Maximizing Biomethane Recovery in Anaerobic Wastewater Treatments: Recent Efforts and Future Prospect

Abstract

Increasing demand for water and energy has emphasized the significance of energy-efficient anaerobic wastewater treatment; however, anaerobic effluents still containing a large portion of the total CH4 production are discharged to the environment without being utilized as a valuable energy source. Recently, gas–liquid membrane contactors have been considered as a promising technology to recover such dissolved methane from the effluent due to their attractive characteristics such as high specific mass transfer area, no flooding at high flow rates, and low energy requirement. Nevertheless, the development and further application of membrane contactors were still not fulfilled due to their inherent issues such as membrane wetting and fouling, which lower the CH4 recovery efficiency and thus net energy production. In this perspective, the topics in membrane contactors for dissolved CH4 recovery are discussed in the following order: (1) operational principle, (2) potential as waste-to-energy conversion system, and (3) technical challenges and recent efforts to address them. Then, future efforts that should be devoted to advancing gas–liquid membrane contactors are suggested as concluding remarks.