Reliable water supply by reusing wastewater after membrane treatment

Abstract

Wastewater reuse is a very reliable source of water supply for water short areas. Integrated membrane systems (IMS), microfiltration or ultrafiltration followed by reverse osmosis (RO), are frequently used for these applications to reliably produce high quality water for aquifer recharge, industrial uses, and irrigation. The reused water can guard against water shortages caused by droughts or increased potable-water usage, especially by supplying industry with high quality water for non-potable uses. Reuse treatment with IMS has many cost advantages over desalination because of the much lower dissolved solids concentrations in most wastewater flows. Experience with IMS for wastewater reuse in Australia, Mexico and the USA will be summarized in terms of operating parameters and water quality. The performance of the IMS systems will be evaluated based on overall recovery, treated water quality, reliability of the membrane systems, flexibility to handle changing feed water quality, ease of operation, and costs. The projects for evaluation include the use and capacity of: municipal wastewaters for industrial processes in Brisbane, Australia and San Diego, CA, USA and for aquifer recharge in Orange County, CA, USA; industrial wastewaters for industrial processes in Panel Rey, Mexico, and wastewaters from electronics manufacturing for aquifer recharge in Chandler, AZ, USA. A case history of each installation, including pilot testing results prior to procuring the system, will be provided to support the performance evaluation. For example, operating experience extensive pilot testing at Orange County, CA have shown that MF/UF pretreatment increases RO flux by 20% while lowering overall operating costs by 40%. Significantly longer chemical cleaning intervals for the RO system when using MF pretreatment were observed at Orange County and Chandler. Design criteria and capital and operating costs for each system will be summarized.