A study at the Southeast Water Pollution Control Plant, San Francisco, California, was undertaken to evaluate the feasibility of replacing its current secondary effluent chlorination system with a 6.57 m3/s ultraviolet (UV) disinfection system. Two vertical lamp units and
one horizontal lamp unit were pilot tested in parallel. The effective UV dose for coliform removal and the effects of feedwater characteristics and reactor hydraulics were examined. The horizontal pilot unit gave a more consistent performance than the vertical pilot units. Based on the test
results, a UV dose of 65 mW·s/cm2 would be required for the plant to achieve the target effluent total coliform level (240 CFU/100 mL) 95% of the time. The large fluctuation of UV disinfection results could be attributed to the wide range of feedwater quality inherent to
a combined sewer system. High suspended solids, characteristic of the plant's secondary effluent during storm events, significantly increased the UV dose required to achieve the target coliform level. Existing UV inactivation models were evaluated. The hydraulic behavior of the pilot units
was found to significantly affect their test results. Higher virus removal efficiency was observed with the UV systems than the full-scale chlorination system.
Water Environment Research® (WER®) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.