AWWA WQTC60693

AWWA WQTC60693 Practical Modeling of Chlorine and Chloramine Decay in Drinking Water
Conference Proceeding by American Water Works Association, 11/15/2004

Work, Lori; Smith, Natalie; Summers, R. Scott

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Application of microbial disinfectants is necessary to achieve primary and secondary disinfection.Unfortunately, most disinfectants react with constituents in drinking water to form unwanted disinfectionbyproducts (DBPs). This is forcing many utilities to optimize their chlorine doses or use chloramines inthe distribution system. In addition, some plants may need to optimize existing treatment processes oradd advanced treatment technologies to control DBPs. These approaches would be facilitated if chlorineand chloramine decay could be more easily predicted under new dose and tretment conditions. This studydeveloped some practical models that predict chlorine and chloramine decay at different doses or afterdifferent treatment processes based on a single disinfectant decay study and results of a simple demandtest at the new conditions. Three source waters with varying water quality were collected from three different drinking watertreatment plants.Upon arrival total organic carbon (TOC), dissolved organic carbon (DOC), UVA254, pH alkalinity, hardness, turbidity, andammonia and bromide concentration were measured for each water.A portion of the source water was filtered with a 1-micron filter and set aside for raw waterdisinfection. The rest of the water was treated in a batch-mixing tank by enhanced coagulation, taperedflocculation and settling, and then filtered with a 1-micron filter. A portion of this water was set aside asfinished enhanced coagulated (EC) water. The rest was further treated with bench-scale advancedtreatment processes: GAC adsorption (GAC), ozonation followed bybiofiltration (Osub3/sub/BF), or alone (Osub3/sub Only), and UV irradiation. Following the designated treatment waterquality analysis data was collected. TOC and UVAsub254/sub were measured for each treated water. In addition,DOC, pH alkalinity, turbidity, and ammonia concentration were measured for each EC water. Includes 7 references, tables, figures.