A Preliminary Comparative Analysis of MBR and CAS Wastewater Treatment Systems

A preliminary analytical study was conducted to compare the cost effectiveness and performance of a membrane bio-reactor (MBR) versus conventional activated sludge (CAS) systems for the treating of wastewater. The design and construction cost, Operation and Maintenance (O&M) cost, and foot-print of different MBR and CAS wastewater treatment plants were collected from various states. The performance data for several parameters were collected from local MBR and CAS wastewater treatment plants. It was found from this study that based on the capital cost considerations; CAS system appears to be a better option compared to the MBR system. However, for long-term operation, foot-print requirements, and treatment effectiveness to meet more stringent effluent characteristics, the MBR system appears to be a better option over the CAS system. Based on the long-term normalized cumulative cost analysis, the MBR system is a better option for a plant operating longer than 67 years, whereas the CAS system is a better option for a plant operating less than 67 years. Therefore, for a long-term operational goal and for performance considerations, the MBR system seems to be the best option.