Effects of feed and operating conditions on the performance and membrane fouling of a submerged anaerobic membrane bioreactor

Abstract

Anaerobic membrane bioreactors (AnMBRs) have been recognized as an effective method for enhanced wastewater treatment and re-use. However, the loss of the membrane performances due to membrane fouling remains a major obstacle in the extensive application of membrane bioreactors. In this study, a hollow fiber submerged anaerobic membrane bioreactor (SAnMBR) was developed for biorefining effluent and industrial wastewater treatment, and membrane fouling was controlled during the operation period. Subsequently, the effects of wastewater characteristics and mixed liquor properties on membrane fouling in an SAnMBR and a thermophilic submerged aerobic membrane bioreactor (TSAMBR) were studied with four different types of industrial wastewaters. In the first part of this thesis, a laboratory-scale hollow fiber SAnMBR was operated for over 5 months to assess its performance for biorefining effluent treatment and the effect of organic loading rate (OLR) on the membrane performance, sludge properties and membrane fouling of the SAnMBR. The results showed that the SAnMBR is not ideally feasible for the treatment of the synthetic biorefining effluent due to the relatively low chemical oxygen demand (COD) removal efficiency (40-70%), the reduction in biogas production rate and the intolerability of the high OLR. A higher OLR resulted in a higher EPS concentration and smaller sludge particles, thus leading to faster membrane fouling. The study showed that too high OLR should be avoided for the operation of SAnMBR.