COST TRENDS OF MBR SYSTEMS FOR MUNICIPAL WASTEWATER TREATMENT

Cost estimates were developed for full-scale (1 and 5 MGD) MBR facilities designed to treat municipal wastewater. These estimates included both capital and operational / maintenance (O&M) costs related to the headworks, MBR process (biological process and membrane system), chlorine disinfection and effluent storage. The costs associated with the membrane systems were developed from budgetary cost quotes provided by suppliers which have recently introduced newly developed MBR products into the U.S. market. Each of these products offer unique design features aimed towards the reduction of capital and/or operation costs. All other costs associated with the MBR facilities were developed from previous conceptual designs performed by the project team and updated using current standard engineering cost indices.Total estimated capital plus annual costs (/1000 gal treated) for the newly developed MBR systems (1-MGD capacity) ranged from 2.02–2.58. The range in costs directly reflects the range in membrane system and membrane replacement costs provided by the participating MBR suppliers. Evaluation of cost estimates for 1 and 5 MGD capacity MBR facilities revealed an average economy of scale of 16.5% for the non-membrane components (i.e. headworks, process basins, buildings etc.) of the MBR facility and 23.6% for the membrane system only. Comparison of the current MBR cost estimates to historical costs estimates (adjusted for inflation) suggest that a steady decrease has occurred in the membrane system cost of MBRs between 2000–2006. However, an opposite trend was observed over the same time period for costs associated with the non-membrane components of the MBR facility. The drop in membrane system costs are attributed to advancements in manufacturing and increased competition in the market place while the increased costs of facility components are attributed to the increased cost of concrete and other raw materials used for plant construction. Results from this analysis shows these opposing trends have resulted in the overall total cost of MBR facilities to be fairly level (i.e.