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.

Use of spray nozzles to recover dissolved methane from an Upflow Anaerobic Sludge Blanket (UASB) reactor effluent

“…The problems associated to packed column technology are flooding, channelling, and wall flow, limiting the operation ranges of liquid and gas flows (Lee et al 2021).…”

“…Among anthropogenic sources, wastewater treatment and their related activities account for around 9% of global environmental methane emissions (Lee et al 2021).…”

“…Even addressing recent efforts and future prospect of membrane contactors, literature shows that fouling and wetting are still inherent problems of this technology and although hydrophobic coatings to avoid wetting and the use of patterns on membrane surfaces, the development of anti-fouling membranes, and the use of solvent-based membrane contactor to avoid fouling are being tested, membrane separation for d-CH 4 recovery from anaerobic effluents still needs to develop its economic viability and process safety (Song et al 2018;Lee et al 2021).…”

Fouling characterisation in PVDF membrane contactors for dissolved methane recovery from anaerobic effluents: effect of surface organofluorosilanisation

“…Membrane contactor processes have shown great feasibility in different applications due to their high energy efficiency and small footprint (Jiménez-Robles et al 2020;Lee et al 2021;Liu et al 2021b;Sohaib et al 2022). Such applications include CO 2 capture from biogas and flue gases, nutrient recovery from wastewaters, biobutanol recovery from fermentation broths, and CH 4 degassing (Klaassen et al 2005;Centeno-Mora et al 2020;Davey et al 2020;Zhang et al 2020;Zhu et al 2020).…”

Graphene Oxide-Based Membranes Intercalated with an Aromatic Crosslinker for Low-Pressure Nanofiltration

“…Over the last few decades, the acceleration of global water scarcity by climate change has necessitated the development of technologies that can produce clean water from alternative water resources, such as seawater and wastewater. Among those technologies, membrane-based separations have played a pivotal role in the conversion of alternative water resources into clean water [ 1 , 2 , 3 , 4 , 5 ]. In particular, low-pressure nanofiltration (NF) is a highly useful and applicable process that offers low energy requirements and excellent removal efficiencies for most contaminants, including divalent ions [ 6 , 7 ].…”