Ultraviolet Disinfection Guidelines for Water Reuse and Equipment Performance Validation Fred Soroushian, CH2M HILL 3 Hutton Center Drive, Suite 200 Santa Ana, CA 92707 Phone: (714)429-2000, E-mail: fsoroush@ch2m.com Robert W. Emerick, Robert H. Hultquist, Richard H. Sakaji, and George Tchobanoglous In 1993, National Water Research Institute (NWRI) collaborated with the California Department of Health Services (DHS) to develop the Ultraviolet Disinfection Guidelines for Wastewater Reclamation in California. The application of UV disinfection for wastewater reclamation has grown significantly since NWRI published these guidelines. In January 2000, NWRI and DHS co-sponsored “UV 2000: A Technical Symposium” to address the technological advancements and regulatory changes that had occurred since the publication of the 1993 UV Guidelines. The focus of UV 2000 was on the need to revise and expand the 1993 UV Guidelines. Because of the substantial interest in North America in applying UV disinfection for production of drinking water, the need to provide guidelines for UV application for drinking water disinfection was also discussed. Following the symposium, NWRI was approached by the American Water Works Association Research Foundation (AwwaRF) to assist in revising the 1993 guidelines. Over the next ten months, NWRI and AwwaRF organized several workshops that brought together international UV experts to rethink and rewrite the guidelines. The panel revised the UV guidelines for water reuse and prepared guidelines for drinking water application of UV systems. The new guidelines are divided into three chapters: Drinking Water, Water Reuse, and Protocols. The intent of the guidelines is to facilitate design and commissioning of UV disinfection systems. They also provide a methodology that can be used to validate UV disinfection system performance. Basis for the Drinking Water Guidelines UV disinfection can be used as an effective barrier for the inactivation of many waterborne pathogens. The use of UV technologies in a multi-barrier treatment train can provide an effective barrier again specific pathogens (e.g., Cryptosporidium and Giardia) and help minimize disinfection byproducts. The UV guidelines apply to the disinfection of drinking water including filtered surface water, unfiltered surface water, and groundwater. For filtered surface waters, water treatment processes prior to UV disinfection could include granular or synthetic medium filtration, membrane filtration (microfiltration [MF], ultrafiltration [UF], nanofiltration [NF], and reverse osmosis [RO]), diatomaceous earth filtration, or slow sand filtration). However, the guidelines are not based on a specific pathogen or inactivation dose requirements; therefore, regulatory agencies will be responsible for establishing the pathogen of concern and the corresponding UV dose requirement. 1 Disinfection 2002 Copyright (C) 2002 Water Environment Federation. All Rights Reserved.