气候变化领域集成服务门户

Laboratory-scale annular reactors were used to evaluate the impact of simultaneously increasing temporal influent monochloramine (NH2Cl) concentrations (0.0 to 3.2 mg chlorine [Cl-2]/L) and chlorine-to-nitrogen mass ratios (0:1 to 3.2:1) on nitrification, allowing evaluation of the recently proposed Nitrification Index (NI) for chloraminated drinking water distribution system operation control. Nitrification was severely affected with a 1.5 mg Cl-2/L NH2Cl residual, becoming undetectable when the NH2Cl residual reached 3 mg Cl-2/L. The calibrated NI was successful in simulating nitrification occurrence. In addition, temporal biofilm sample results demonstrated that viable ammonia-oxidizing bacteria were (1) dominated by Nitrosomonas europaea related species for an NH2Cl residual less than approximately 0.4 mg Cl-2/L, (2) dominated by N. oligotropha-related species for an NH2Cl residual between 0.4 and 1.5 mg Cl-2/L, and (3) not detected once the NH2Cl residual was maintained at approximately 3 mg Cl-2/L.