COMPARISON OF MBR FACILITY DESIGN PROCESSES

Rapid urbanization, population growth, and finite water resources coupled with limited assimilative capacity of the receiving waters have prompted many communities to consider innovative technologies for converting wastewater to reusable water. Over the last decade, membrane bio-reactor (MBR) based treatment technology has emerged as a viable alternative to meet this growing demand. The MBR technology couples membrane filters (microfiltration or ultrafiltration) with an activated sludge biological treatment process to eliminate the need for a combination of clarifiers and tertiary filters for separation of high quality effluent from the mixed liquor solids. The MBR technology also eliminates the sludge settleability concerns and although unacknowledged by many regulatory agencies, MBR facilities provide a higher degree of bacteria and virus removal than conventional treatment technologies before any post-treatment disinfection processes. Major benefits of this technology are the elimination of major structures for clarification and filtration, operation at higher MLSS concentrations to downsize reactor sizes or decrease waste sludge quantities, significant reduction in microbial contamination, and reliable production of a high quality effluent.Recognizing the relevance of MBR technology to water quality and supply sustainability issues, this study compares the design practices and procedures applied to nine MBR facilities (see Table - 1) that are currently in operation and/or final stages of construction for communities in the metro Atlanta area and industries in other locations. Design parameters compared include effluent quality, reactor volumes, MLSS concentrations, flux, sludge age, and membrane life. In addition to summarizing the preliminary results of this study, this paper examines the changing role of the membrane vendor in design of MBR facilities based on membrane procurement procedures followed at these facilities.