CONTROLLING NITRIFICATION IN CHLORAMINATED SYSTEMS

Of US water systems that chloraminate, an estimated two thirds experie nce some degree of nitrification in the distribution system. Measures utilities use to control nitrification were investigated through field sampling, evaluation of utility data, laboratory tests, and case stud ies of systems that have evaluated or attempted to control nitrificati on episodes. Effective control methods included instituting periodic b reakpoint chlorination, reducing the available ammonia concentration, increasing chloramine residuals, cleaning the distribution system, and decreasing system detention time. Some control methods were superior for controlling a specific nitrification episode, whereas others showe d more promise for reducing the long-term potential for nitrification occurrence. According to the authors, the most important steps utiliti es can take to control nitrification are to thoroughly understand thei r systems' chloramine chemistry and to establish an effective monitori ng strategy.