Membrane Bioreactor (MBR) is the latest technology for biological degradation of soluble organic impurities. MBR technology has been in extensive usage for treatment of domestic sewage and industrial waste treatment applications. The MBR process is very similar to the conventional activated sludge process. Both have mixed liquor solids in suspension in an aeration tank. The difference in the two processes lies in the method of separation of bio-solids. In the MBR process, the bio-solids are separated by means of a polymeric membrane based on microfiltration or ultrafiltration unit, as against the gravity settling process in the secondary clarifier in conventional activated sludge process. The system operates at 12 g/l MLSS which results in a smaller aeration tank. The BOD5 after treatment is in general < 5 mg/L.