
Membrane Bioreactor (MBR) is a relatively new yet fast maturing technology in the area of wastewater treatment. Prevalent technologies in wastewater treatment such as a conventional activated sludge (CAS) system are gradually replaced by MBR. Conventional systems had problems in settling the activated sludge used in the secondary clarifiers. This issue has been effectively resolved by MBR technology. Commercial MBR processes employed today utilize membranes for filtration purposes which reject any solid effluent materials formed as a byproduct of biological processes. The principal difference with its predecessor technology such as CAS systems is the replacement of secondary clarifier or settlement tank with a membrane. MBR's are generally employed for larger scale water purification systems. Primarily such systems are utilized by commercial and industrial sectors or by municipalities. With growing population and increasing requirements for sufficient clean and fresh water, treatment of wastewater is imperative. Of all the MBR's employed globally, a majority belongs to municipal corporations for treatment of domestic wastewater. MBR's are classified as submerged/immersed MBR's where membranes are submerged in the aeration tank itself and external/side stream MBR's. In side stream MBR's, mixed wastewater is pumped from the aeration tank to the membrane. The MBR markets are shifting from the initial regions of adoption such as Europe, U.S.A and Japan and gradually moving towards emerging economies (China, South Korea and Brazil) with larger populations and limited fresh water supply.