AWWA MTC64597

Membrane bioreactor (MBR) technology combines the functions of a biological reactor with membrane separation. The MBR replaces two stages of the conventional activated sludge process (biotreatment and clarification) with a single, integrated process. The main advantages of MBRs include reduced footprint, reduced sludge production due to a high biomass concentration in the bioreactor, and higher quality product water. The most substantial drawback of MBRs is membrane fouling. Fouling causes permeate flux decline and increases the frequency of membrane cleaning and replacement. Approximately 98% of MBR systems are aerobic MBRs. They have mostly been used to treat domestic and industrial wastewater, where a small footprint is required, water reuse is desired, or stringent discharge standards exist. In recent years there has been growing attention towards the use of anaerobic MBRs (AnMBRs), due to their advantages over aerobic systems, such as lower sludge production and reduced energy requirements. Despite these advantages, anaerobic MBRs are a slow-developing technology, mainly because of fouling problems. Much progress has been made in the study of fouling mechanisms in aerobic MBRs, but the same cannot be said for anaerobic MBRs. Fouling in anaerobic systems is still poorly understood. Although it has been established that struvite, bacterial cells, and colloidal matter are major membrane foulants, there is still limited information on the role of extracellular polymeric substances (EPS) and soluble microbial products (SMP) on the fouling of anaerobic MBR membranes. Furthermore, a novel approach in anaerobic MBRs is represented by the submerged configuration. At present time there is very little information about this configuration, and specifically, only two studies (Fawehinmi et al. 2005 and Hu and Stukey 2006) have been identified in the literature concerning submerged anaerobic MBRs. The main objectives of the current study are to investigate the influence of operating conditions on the production of EPS and SMP in submerged AnMBRs and to determine the role of these metabolic byproducts on membrane fouling. Includes 6 references, figure.