Influence of high lipid containing wastewater on filtration performance and fouling in AnMBRs operated at different solids retention times

In this study, the filtration performance of anaerobic membrane bioreactors when treating a high strength lipid rich wastewater, corn-to-ethanol thin stillage, is evaluated at different solids retention times (SRTs). Long chain fatty acid (LCFA) inhibition, observed at high SRTs, concomitantly occurred with floc deterioration and soluble microbial product release. On the other hand, accumulation of LCFA on the sludge modified its surface hydrophobicity. Remarkably, a lesser degree of fouling was observed at increased sludge hydrophobicity. Cake layer formation was found as the most important contributor to membrane filtration resistance, whereas chemical cleaning tests indicated a low degree of irreversible organic fouling. Moreover, inorganic fouling in the form of phosphorus precipitates was identified both in the cake layer and on the membrane.