The Effect of Membrane Material on Fouling in Anaerobic Membrane Bioreactor Treating Domestic Wastewater

Roy Bernstein, Desalination & Water Treatment , Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
Amit Grossman, Desalination & Water Treatment , Ben-gurion University Of The Negev, Midreshet Ben-gurion, Israel
Gideon Oron, Desalination & Water Treatment , Ben-gurion University Of The Negev, Midreshet Ben-gurion, Israel
Yang Yang, Desalination & Water Treatment , Ben-gurion University Of The Negev, Midreshet Ben-gurion, Israel

Anaerobic membrane bioreactor (AnMBR) is an emerging advanced wastewater treatment technology (WWT). Yet, its potential is still unattained and its application is very limited due to several drawbacks, of which the high energy cost for fouling control is perhaps the most significant.

The goal of this study was to explore the effect of the membrane hydrophilicity on the fouling propensity in a lab-scale high throughput AnMBR treating real domestic wastewater. Three common UF membranes with similar morphological properties were investigated: polyacrylonitrile (PAN), a hydrophilic membrane, and polyethersulfone (PES) and polyvinyl difluoride (PVDF), hydrophobic membranes. The membranes pore size, surface roughness, contact angle zeta potential, and water permeability were measured. Then, the membranes were placed in the high-throughput AnMBR. The fouling of each membrane was evaluated by monitoring the changes in the trans-membrane pressure (TMP). In addition, each type of membrane was taken-out after 1, 4, 8 and 30 days, and the fouled membrane surface and the foulants compositions in the extracellular polymeric substance (EPS) were analyzed.

The TMP of the three membranes, as well as the concentrations of the different components in the EPS, were similar during the first few days of filtration. After several days, the TMP of the hydrophobic membranes (PES and PVDF) rapidly increased, whereas the TMP of the hydrophilic membrane (PAN) remained relatively stable  throughout the 30 days experiment. This was also evident by a much higher EPS concentration measured on the PES and PVDF membranes surface compared with that measured on the PAN membrane surface. It is estimated that the low fouling of the PAN membrane was due to the combination of the relatively low hydrophilicity and the frequent physical cleaning (gas sparging and backwashing). Further research will focus on investigating other membranes and the effect of morphological parameters on fouling.

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