It is important for water utilities to provide esthetically acceptable drinking water to the public, because our consumers always initially judge the quality of the tap water by its color, taste, and odor (T&O). Microorganisms in drinking water contribute largely to T&O production and drinking water distribution systems (DWDS) are known to harbor biofilms and microorganisms in bulk water, even in the presence of a disinfectant. These microbes include T&O-causing bacteria, fungi, and algae, which may lead to unwanted effects on the organoleptic quality of distributed water. Importantly, the understanding of types of these microbes and their T&O compound-producing mechanisms is needed to prevent T&O formation during drinking water distribution. Additionally, new disinfection strategies and operation methods of DWDS are also needed for better control of T&O problems in drinking water. This review covers: (1) the microbial species which can produce T&O compounds in DWDS; (2) typical T&O compounds in DWDS and their formation mechanisms by microorganisms; (3) several common factors in DWDS which can influence the growth and T&O generation of microbes; and (4) several strategies to control biofilm and T&O compound formation in DWDS. At the end of this review, recommendations were given based on the conclusion of this review.

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To comprehensively describe the effect of residual chlorine and disinfection by-products (DBPs) on water quality in water distribution systems (WDS) and optimize rechlorination cost, this study developed a multi-objective optimization model of water quality and rechlorination cost. Firstly, chlorine decay and DBPs formation were simulated using EPANET_MSX. An improved non-dominated sorting genetic algorithm II (NSGA-II) with real code was used to optimize the multiobjective model and Pareto fronts could be obtained under different conditions. The results showed that Pareto fronts obtained by average value were better than those obtained by standard deviation and multiplication. Moreover, with the number of boosters increased, maximum value of water quality increased and rechlorination cost decreased. Wall chlorine decay constants were the most important on Pareto fronts, followed by the number of chlorination nodes, proportional coefficients of trihalomethanes (THMs) generation based on residual chlorine consumption, and THMs concentration.

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