AWWA WQTC69486

Since early 2002, the Alameda County Water District (ACWD) has controlled bromate formation using pH suppression via the addition of carbon dioxide ahead of ozonation. By reducing the pH, ACWD has been able to maintain the plant effluent bromate concentration at less than the regulatory standard of 10 µg/L. While the pH suppression strategy has been successful in controlling bromate, it can be expensive under certain conditions. A full-scale investigation was conducted to evaluate the addition of chloramine ahead of ozonation, and compare the performance of this bromate control technique to that of pH suppression. This paper presents the results of the bromate control investigation to date. Chloramine addition was shown to be equally effective to pH reduction for controlling bromate, at a significant reduction in cost. Potential effects of chloramine addition on downstream processes have not yet been determined for this plant, and a second phase of the study is planned to assess these long-term impacts. Includes 7 references, tables, figures.