Abstract
Membrane fouling is a considerable challenge for the stable operation of anaerobic membrane-based bioreactors. Membrane used as a cathode is a common measure to retard fouling growth in anaerobic electrochemical membrane bioreactors (AnEMBR), which; however, cannot avoid the fouling growth. Here we report a strategy using the membrane as an anode to resist membrane fouling in an AnEMBR. Although aggravating in the initial stage, the fouling on the anode membrane is gradually alleviated by the anode oxidation with enriching exoelectrogens to finally achieve a dynamic equilibrium between fouling growth and decomposition to maintain the operation stable. A mesh-like biofilter layer composed of cells with less extracellular polymeric substance (EPS) is formed on the membrane surface to lower the trans-membrane pressure and promote the interception of the anode membrane. The membrane has high electron storage and transfer capacities to accelerate the oxidation of the intercepted fouling materials, especially, the redundant EPSs of the biofilter layer.
Highlights
Membrane fouling is a considerable challenge for the stable operation of anaerobic membrane-based bioreactors
Membrane fouling is a considerable challenge for the stable operation of anaerobic digester with membrane bioreactor technology (AnMBR), though the produced biogas may sparge the surface of the membrane to alleviate the fouling[2,3,4]
Proteins and polysaccharides are the main constituents of the extracellular polymeric substances (EPS), and EPS as well as microbial cells contribute a majority of the membrane fouling of MBR17,18
Summary
Membrane fouling is a considerable challenge for the stable operation of anaerobic membrane-based bioreactors. Once the fouling is maintained to a certain extent to intercept particles and ensure the sufficient water flux through the cake layer, the pore size of membrane is not required to be quite small to directly intercept the particles, but can be amplified to lessen the fouling that blocks in the pores Complex organics such as proteins and polysaccharides have been reported to be decomposed in the anode of the bioelectrochemical system via microbial anodic oxidation[12,13,14]. We expect that the sludge cake layer formed on the anode membrane surface functions as a fouling-resistant biofilter to intercept particles of the effluent, and the mechanisms of fouling decomposition and fouling roles are explored
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