Producing High-Purity Recycled Water for Industrial Applications with Microfiltration and Reverse Osmosis: Lessons Learned

The East Bay Municipal Utility District (District), with the assistance of Black & Veatch, studied the feasibility of treating secondary and tertiary effluents using microfiltration (MF) followed by reverse osmosis (RO) to produce high-purity, recycled water for use as boiler make-up water at a local refinery. A pilot-scale test program was developed to demonstrate the ability of the MF and RO technologies to treat secondary effluent from the West County Wastewater District (WCWD), and tertiary effluent from the District's North Richmond Water Reclamation Plant (NRWRP). The pilot-scale test systems consisted of a 25 to 40 gallons per minute (gpm) MF system and a 12 to 15 gpm RO pilot-scale system. The pilot-scale systems were operated for a total of four months. This paper summarizes the pilot test program and results, and discuses the design considerations that will be applied to the full-scale system. When treating secondary and tertiary effluents, the pilot-scale systems were able to produce permeate that met the water quality objectives of the project while operating at an overall recovery rate between 77.5 to 79 percent.