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

Benny M B Ensano,Mark D G De Luna,Florencio C Ballesteros,Laura Borea,Vincenzo Belgiorno,Vincenzo Naddeo

doi:10.3389/fenvs.2016.00057

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.

Highlights

Numerous water and wastewater treatment processes have been employed in order to minimize water pollution and to augment drinking water resources (de Luna et al, 2009; Naddeo et al, 2011; Cesaro et al, 2013; Secondes et al, 2014; Ballesteros et al, 2016)
In some submerged membrane electro-bioreactor (SMEBR) studies, the cathode is designed as part of the membrane module [e.g., carbon cloth electrode fabricated with polyvinylidene fluoride (PVDF) membrane or copper wire cathode inside a PP non-woven sheet] or an electrically conductive low- cost membrane is used as the cathode itself [e.g., terylene cloth modified with polypyrrole (Ppy), polyester filter cloth modified with PPy coated graphene (GR/Ppy), or with PPy coated graphene oxide (GO/Ppy)] (Akamatsu et al, 2012; Liu et al, 2012a,b, 2013b; Zhang et al, 2015)
Membrane fouling is a major limitation in membrane bioreactors (MBR) operation that should be resolved

Summary

Introduction

Numerous water and wastewater treatment processes have been employed in order to minimize water pollution and to augment drinking water resources (de Luna et al, 2009; Naddeo et al, 2011; Cesaro et al, 2013; Secondes et al, 2014; Ballesteros et al, 2016) Among these techniques, conventional activated sludge (CAS) process is the most widely used method due to Electrochemical Processes in Membrane Bioreactors its effective mineralization of organic and inorganic compounds from various types of wastewater. A more promising alternative for wastewater remediation is the combination of the activated sludge treatment with membrane filtration process This technology, known as membrane bioreactor (MBR), differs from CAS since a membrane module is used instead of the secondary clarifier to separate activated sludge from the final effluent (Xing et al, 2000). Its applications have extended widely from treatment of municipal wastewater (Weiss and Reemtsma, 2008; Ma et al, 2013; Zhou et al, 2015) to removal of toxic and hazardous compounds in landfill leachate (Ahmed and Lan, 2012), and industrial wastewaters (Artiga et al, 2005; Yigit et al, 2009; Palogos et al, 2014)

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