Application of the membrane biological reactor system for combined sanitary and industrial wastewater treatment

In the early 1990s, the General Motors Corporation (GM) adopted the use of the membrane biological reactor (MBR) system for treatment of automotive manufacturing plant wastewaters both in the US and internationally. The MBR process consists of a suspended growth biological reactor combined with a membrane unit either located external to the bioreactor or mounted directly within the bioreactor, Recently, the GM Worldwide Facilities Group operated an external membrane MBR system pilot plant at the Delphi Steering manufacturing plant in Saginaw, MI treating combined industrial and sanitary wastewater, The pilot plant study was completed in order to support the design of a full-scale MBR system for the Delphi Steering plant located in Queretaro, Mexico. The major equipment items utilized in the pilot study were a 1.51 m(3) complete mix, aerobic bioreactor coupled to a cross-flow, tubular, ultrafiltration membrane unit containing 0.98 m(2) of membrane area. After a start-up phase, the pilot plant was operated under various wastewater feed ratios (i.e., ratio of sanitary to industrial feed rate) at a constant bioreactor hydraulic retention time (HRT) of approximately 1 day and a solids retention time (SRT) of approximately 70 days. The results from the pilot plant study implied that a full-scale MBR system operating at a sanitary to industrial wastewater feed ratio in the ranee of 1:1 to 4:1, and at HRT and SRT values of respectively, 1 and 70 days, should result in an effluent chemical oxygen demand and biological oxygen demand of respectively, less than 400 and 10 mg/l. (C) 2000 Published by Elsevier Science Ltd.