x-MBRs

Many different types of membrane bioreactors (MBRs) are being developed to treat wastewater. We can distinguish these based on labels if x-type MBRs, with the aerobic MBR (AeMBR), often just referred to as an MBR, being the most common type of system used to treat domestic and many other types of wastewaters. AeMBRs have the advantages compared to activated sludge of a smaller footprint (more compact reactor), and production of a high quality effluent in terms of solids concentrations as the effluent passes through the ultrafiltration membranes. The main disadvantage of AeMBRs are the high energy demands relative to activated sludge processes, and membrane fouling which means that the membrane must be periodically chemically cleaned or replaced.

At Penn State, we are researching the use of anaerobic membrane bioreactors (AnMBR) that contain a fluidized bed of granular activated carbon (GAC). These anaerobic fluidized bed membrane bioreactors (AFMBRs) were invented by others as a second step in wastewater treatment, which followed wastewater treatment using anaerobic fluidized bed reactors. For our work, we are examining the use of AFMBRs as a second treatment step following treatment using microbial fuel cells (MFCs). While MFCs can treat wastewater and produce electricity, once the COD of the wastewater decreases below ~150 mg/L, the current production is very low. Thus, AFMBRs are ideally well suited to reduce the COD to levels suitable for discharge or water reuse.

The research is addressing: the effectiveness of combined MFC-AFMBR systems; impacts of organic loading on AFMBRs; startup procedures for acclimating the GAC particles; development of aerobic fluidized bed MBRs (AOFMBRs); and nutrient removal in different types of MBRs.