AWWA WQTC57151

Many utilities use chloramines as their residual disinfectant because of reduced trihalomethane levels, and improved overall water quality compared to free chlorine. However, when discharged to the environment, chloraminated water is not the only toxic to aquatic species but the ammonia component can potentially contribute to nutrient loading and therefore lead to biostimulation of sensitive receiving waters. Most utilities that chloraminate, only dechlorinate (remove the chlorine component) discharges to the environment. As part of its complex transmission system, the San Francisco Public Utilities Commission (SFPUC) routinely transfers an average of 30 MGD of treated water to a local water body, Crystal Springs Reservoir. After the SFPUC converts its system-wide residual disinfectant to chloramine, this significant water transfer will be also chloraminated. To maintain the pristine quality of this reservoir, the SFPUC is currently constructing a 200 MGD capacity dechloramination facility to remove both the chlorine and ammonia in water releases to Crystal Springs Reservoir. The Pulgas Dechloramination Facility will use breakpoint chlorination followed by dechlorination. This paper presents the work conducted by the SFPUC and its consultant, Camp Dresser & McKee, to evaluate the breakpoint chlorination process for this application. Bench scale tests were conducted during the conceptual engineering phase of the Chloramine Conversion Project. For the 10 percent engineering design, a continuously flowing pilot study was conducted to: evaluate impacts of water quality on the breakpoint process; optimize required chemical doses; determine required reaction times; and, establish design criteria for the full-scale facility. Includes 7 references, table, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2002

Number of Pages:

17

File Size:

1 file , 870 KB