Anaerobic membrane bioreactor towards biowaste biorefinery and chemical energy harvest: Recent progress, membrane fouling and future perspectives

Anaerobic membrane bioreactor (AnMBR) holds great promise to treat a broad range of waste streams for concurrent pollutants transformation and biofuels harvest while producing less digestate residuals. In this review, recent research advances, new discoveries and commercial application status of AnMBR technique were summarized and reported. A comprehensive comparison analysis designed herein demonstrated its fascinating superiorities over the conventional activated sludge-based processes with regards to good permeate quality, less digestate residuals, low operational costs, net profit/energy output, and outstanding economic and environmental benefits. Despite the great progress achieved previously, there are still numerous challenges head for AnMBR platform applications to be tackled, particularly for severe membrane fouling, low methane content in biogas, highly dissolved methane, poor ammonia removal and phosphorus recovery, etc. To address the above problems, a new-generation process, i.e. so-called Integrated Multistage Bio-Process (IMBP) constituted of solar-driven bioelectrochemical system (BES)-AnMBR, partial nitritation/anammox (PN/A), nitrate reduction via anaerobic oxidation of methane (AOM) and biological/chemical phosphorus precipitation units, was proposed in this article, with versatile capabilities in simultaneous biowastes valorization, CO2 electromethanogenesis and simultaneous biogas upgrading, in-situ fouling control, ammonia removal, dissolved methane reutilization, and phosphorus recover as hydroxyapatite-rich nutrients. Despite the uncertainties about whether this approach possesses the powerful potential to dominate the future, but most surely, this hybrid concept will enhance the deployment and industrial competitiveness of AnMBR-based technologies in real-world scenarios, facilitating the establishment of the energy-sustainable and low-carbon society. Of course, more efforts are still required to demonstrate the feasibility of this integrated biorefinery approach. Nonetheless, this review opens up new research opportunities to integrate with other newly emerging processes to develop robust, multifunctional and sustainable AnMBR-based technologies towards biowaste biorefinery, chemical energy harvest and green, carbon-neutral society.