Combination of Electrochemical Processes with Membrane Bioreactors for Wastewater Treatment and Fouling Control: A Review

Abstract

This paper provides a critical review about the integration of electrochemical processes into membrane bioreactors (MBR) in order to understand the influence of these processes on wastewater treatment performance and membrane fouling control. The integration can be realized either in an internal or an external configuration. Electrically enhanced membrane bioreactors or electro membrane bioreactors (eMBRs) combine biodegradation, electrochemical and membrane filtration processes into one system providing higher effluent quality as compared to conventional MBRs and activated sludge plants. Furthermore, electrochemical processes, such as electrocoagulation, electrophoresis, and electroosmosis, help to mitigate deposition of foulants into the membrane and enhance sludge dewaterability by controlling the morphological properties and mobility of the colloidal particles and bulk liquid. Intermittent application of minute electric field has proven to reduce energy consumption and operational cost as well as minimize the negative effect of direct current field on microbial activity which are some of the main concerns in eMBR technology. The present review discusses important design considerations of eMBR, its advantages as well as its applications to different types of wastewater. It also presents several challenges that need to be addressed for future development of this hybrid technology which include treatment of high strength industrial wastewater and removal of emerging contaminants, optimization study, cost benefit analysis and the possible combination with microbial electrolysis cell for biohydrogen production.

Assessment of Microbial Community Structure and Function in Serially Passaged Wastewater Electro-Bioreactor Sludge: An Approach to Enhance Sludge Settleability

“…In activated sludge process, the solids/liquid separation typically takes place through a separation of spontaneously aggregated flocs by gravity sedimentation in secondary clarifiers 1 , while in membrane bioreactors, the biosolids are separated by means of a polymeric membrane based on microfiltration or ultrafiltration 2 . The integration of electrochemical processes into wastewater treatment bioreactors combine biodegradation, electrochemical, and sludge separation processes into one system, achieving high effluent quality when compared to conventional process 3 – 5 . Current density (CD) is a crucial factor which affects the performance of electrochemical treatment in electrically enhanced wastewater treatment bioreactors, controlling the dosing rate of metal ions and the gas bubble density that are released in the solution via redox reactions of electrodes 6 .…”

Effect of hydraulic retention time on microbial community structure in wastewater treatment electro‐bioreactors

“…The integration of electrochemical processes into membrane bioreactors (MBRs) combines biodegradation, electrochemical and membrane filtration processes into one system achieving high effluent quality as compared to conventional MBRs and activated sludge processes (Ensano et al, 2016). New and cheaper developments have suggested that the continuous and intermittent application of a direct current (DC) field has proven to enhance membrane filterability and is similarly effective in controlling membrane fouling (Akamatsu, Lu, Sugawara, & Nakao, 2010;Akamatsu et al, 2012;Liu, Liu, Gao, & Yang, 2012;Liu et al, 2014).…”

Removal of Pharmaceuticals from Wastewater by Intermittent Electrocoagulation

“…This can be explained by the interactions between aluminium and phosphate ions inside the reactor which resulted in the significant removal of the latter from the solution [57]. Aside from adsorption onto Al(OH) 3 coagulants, excess aluminium ions (Al 3+ ) react with phosphorous ions to form (AlOH) 3 (PO 4 ) 2 (s) and AlPO 4 (s) that precipitate out in the bioreactor according to the following reactions (Equations (7) and (8)) [58]:…”