AWWA WQTC65868

The objective of this project was to design a low pressure membrane filtration system that best utilizes the existing infrastructure and is capable of concurrent operation with the existing conventional filtration system before its conversion into a membrane filtration. Several alternatives, including conventional filtration, pressure membranes, and submerged membranes were evaluated. The submerged membrane alternative was selected as the preferred alternative because it has the lowest life-cycle capital and O&M costs and also meets the City's objectives. To make the best use of the existing infrastructure and to facilitate the eventual conversion of the existing conventional filtration to membrane filtration in the future, the membrane system is designed to fit into the existing sand filter basins in the future. To insure that the selected membrane represents the lowest overall project costs, the two most representative submerged membranes (USFilter/Memcor CMF-S system and Zenon Zeeweed® 1000 system) are fully designed, from which the contractor can select the lowest cost membrane. The challenges of this project include: almost double the amount of work without changing the deadlines; finding the optimal design for each system that fit into the existing basin dimension; and, making sure the membrane system is hydraulically compatible with the conventional system to facilitate concurrent operation. The approaches adopted in the design include: developing a unified P&ID for the two membranes to insure fair comparison; being flexible in layout for optimum performance of each membrane system; and, providing future provisions for phase II and build-out expansions. This paper presents the key factors considered and challenges encountered during membrane system design for the concurrent operation with the existing conventional systems. Includes tables, figures.