Membrane-Coupled Aerobic Bioreactors for Use in Wastewater Treatment

A membrane-coupled aerobic bioreactor (MBR) can be described as a system coupling the aerobic bioreactor, or activated sludge tank, of a wastewater treatment system with a microor ultrafiltration membrane. The membrane serves to separate the suspended material in the sludge so that the permeate stream is free of chemicals, microorganisms, and other contaminants. The membrane may be either internally mounted so that the retentate remains in the bioreactor or externally mounted so that the retentate is either recycled to the bioreactor or wasted. The membranes are available in a variety of structures and materials which can be suited to individual application needs. The MBR has several advantages over conventional activated sludge processes, including reduced area, consistently high effluent quality, and operational separation of solids retention time (SRT) and hydraulic retention time (HRT). A mathematical model has been developed for an MBR and tested against experimental data with reasonable agreement. Additionally, studies have been conducted to investigate the effects of changing operational parameters on the MBR as well as the microbial diversity of an MBR as compared to a conventional activated sludge system.