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This paper discusses the planning and design for a large membrane bioreactor system.Specifically, the preliminary design study, a pilot testing study, and the final design arediscussed for a new 10-mgd membrane bioreactor currently under construction for theLoudoun County Sanitation Authority in Virginia. The preliminary design study comparedmembrane bioreactors to conventional technologies, resulting in the conclusion thatmembrane bioreactors are cost competitive with conventional technology for achieving high-qualityeffluent.The pilot testing study confirmed the results of the preliminary design study and resulted insome significant findings regarding the effects of pretreatment and coagulant addition onmembrane performance. Based on the results of the pilot testing operation, a membrane-flux maintenance strategy was developed to optimize performance through a combination ofpretreatment, scheduled maintenance cleaning, and coagulant addition. Throughout the pilotoperating period, the pilot membrane bioreactor (MBR) was operated at an average membrane flux rate ofapproximately 33 percent higher than that recommended by the manufacturer.The paper discusses how the findings of the pilot testing study were incorporated into thedesign of the full-scale facility. The completed facility will be one of the largest MBRs inthe United States. As one of the first MBR designs in the 10-mgd size range, scale up of thetechnology for the treatment of high flows was an important consideration. The designincluded features such as full preliminary and primary treatment with coarse and finescreening of MBR influent, flow equalization capabilities to address the peak flowlimitations of membranes, individual membrane trains to facilitate membrane cleaning, etc.The role of a membrane vendor pre-selection program is also discussed as a means forreducing risk to the owner as means of finalizing equipment cost and for developing apartnership between the engineering consultant and the selected vendor. Includes tables, figure.

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Edition: Vol. - No. Published: 03/01/2005 Number of Pages: 13File Size: 1 file , 410 KB