Answering the Challenge

Abstract

Abstract As a result of the need for ever‐expanding drinking water supplies in an area short on such new sources, the City of San Diego purchased an electrodialysis reversal (EDR) system in 1998 to desalinate tertiary treated wastewater. The EDR system was installed to produce a low TDS product from treated wastewater, then blend and supply this high‐quality irrigation water to golf courses, parks, plant nurseries, and other water users. The initial plant produced 3.3 mgd of blended water. The city elected to use EDR because of its lower costs compared with the conventional use of MF‐RO. EDR also operates at higher water recovery, and with no chemical feed required other than an allowable use of free chlorine in the feedwater. As a result of the success of the “alternative water supply” program, the EDR system has been expanded to where it will produce a blended flow of up to 12 mgd by early 2005. This successful installation has been verified by recent testing of EDR and MF‐RO, showing that EDR is up to 40% less costly based on present worth analysis of capital, infrastructure, and long‐term O&M costs.