EVALUATION AND OPTIMIZATION OF MEMBRANE BIOREACTORS FOR WATER RECLAMATION

Four leading commercially available MBR (membrane bioreactor) systems were operated at the pilot scale over a 16-month period at the Point Loma Wastewater Treatment Plant (PLWTP) located in San Diego, CA. The four MBR systems tested included Kubota, US Filter / Jet Tech, Zenon and Mitsubishi Rayon. A primary objective of the pilot testing was to obtain operational and water quality data on the Kubota and US Filter MBR systems, which are relatively new to the US market. Furthermore, the project was conducted to assess the performance of MBR systems while operating on advanced primary effluent containing coagulant and polymer. Phase I pilot testing was conducted between April - October 2002. During this time period, both the US Filter and Kubota MBR systems were operated on raw wastewater from the PLWTP. Phase II pilot testing began in November 2002 and ended in August 2003 during which time the four MBR systems were operated on advanced primary effluent. Pilot test results from the two new suppliers (Kubota and US filter) showed the systems achieved high removal of particulate, microbial and organic contaminants. This is an important finding for the water quality community as it increases the number of MBR suppliers proven to be suitable for reclaimed water production. In addition, testing results indicated that the MBR systems could operate successfully on advanced primary treated effluent, which contains residual coagulant and polymer. This finding is significant as operation of MBRs on advanced primary effluent may prove to be more cost effective than operation on raw wastewater due to the lower solid and organic content. Lastly, it was shown MBR systems could be successfully operated other under optimized conditions including flux and HRT.