Membrane distillation bioreactor (MDBR) for wastewater treatment, water reuse, and resource recovery: A review

Membrane bioreactors (MBRs) have been well established as an advanced wastewater treatment technology that combines activated sludge with a pressure-driven membrane separation process. They have been widely applied in municipal and industrial wastewater treatment systems due to their advantages over conventional activated sludge systems. However, MBRs still face major issues hindering their widespread implementation such as poor effluent quality due to low retention of trace organic contaminants, instability due to changing operating conditions, and organic membrane fouling. Membrane distillation (MD) bioreactor (MDBR) is a novel wastewater treatment technology that combines MBRs with an MD unit either separated at a side stream or submerged in the bioreactor. The concept of hybrid MDBR configuration was firstly introduced in 2007 which was followed by numerous journal articles. These studies demonstrated the MDBR potential for water, nutrients, bioenergy, and other value-added product recovery from domestic and industrial wastewater; however, there is still a lack of a comprehensive study that shows the full MDBR potential. Hence there is a need for a dedicated review that summarize and critically analyse these research findings and highlight the research gaps to provide clear path for future research. This review presents system availability and applications of hybrid MDBR. In particular, the review presents brief introduction of MBR and MD technologies followed by covering the evolution of MDBR as a novel technology for municipal and industrial wastewater treatment. Several applications of MDBR systems are reviewed with a focus on system performance and removal efficiencies. The potential of MDBR to widen wastewater reuse and achieve nutrient and biogas recovery is also presented. Finally, the main challenges that hinder the development of MDBR are discussed while recommendations on future perspectives towards MDBR commercialization are suggested.