Second‐Order Chlorine Decay and Trihalomethanes Formation in a Pilot‐Scale Water Distribution Systems

Abstract

It is well known that model-building of chlorine decay in real water distribution systems is difficult because chlorine decay is influenced by many factors (e.g., bulk water demand, pipe-wall demand, piping material, flow velocity, and residence time). In this paper, experiments were run to investigate the kinetic model of chlorine decay and the formation model of trihalomethanes (THMs) in pilot-scale water distribution systems. Experimental results show that the rate constants of chlorine decay, including wall decay and bulk decay, increasing with temperature. Moreover, the kinetic model of chlorine decay and the formation model of THMs describe experiment data of pilot-scale water distribution systems. The effect of different piping material on chlorine decay and THMs formation were also investigated. The rate constants of chlorine decay are ranked in order: stainless steel pipe, ductile iron pipe, and last, polyethelene pipe because wall decay is the largest in stainless steel pipe than that in other piping material. Correspondingly, the rate of THMs formation follows the order of stainless steel pipe, ductile iron pipe, and last, polyethelene pipe because of less chlorine in bulk water reacting with the trihalomethane formation potential (THMFP). Water Environ. Res., 84, 656 (20t2).

The Effect of Membrane Treatment on Chlorine Decay and Trihalomethanes Formation in Water Distribution Systems

“…Sodium hypochlorite with purity 97.5% was from Sinopharm Chemical Reagent Company (SCRC), and its solution was prepared with tap water from Hangzhou and then added to the loop to achieve the initial desired chlorine level [6]. Every half an hour, 50 ml of aqueous samples were taken.…”

Predictive capability of THM models for drinking water treatment and distribution

“…A literature review of THM models was conducted using Scopus and Google Scholar. [14][15][16][17][18][19][20][21][22][23][24][25] Search results were restricted to include articles with titles or abstracts containing the keywords "THM"/"trihalomethanes", "model", and "water". Results were restricted to include at least one secondary term, such as; "DBP", "chlorine", "treatment plant", "distribution system", or "premise plumbing" to be included within the scope of the search.…”

“…For example, reaction rate coefficients have been used in some models to relate changes in water quality variable concentrations to THM formation. 22,43 Differences in physicochemical and biological characteristics between systems would affect the relative impact of water quality variables on THM formation, as well as the values of their reaction coefficients. For these reasons, mechanistic models may not be as useful for predicting water quality behavior in different systems.…”

The Laboratory Study of Drinking Water Biofilms

“…Researches on biofilms community have been performed with the circulatory system of the DWDS in the laboratory. In the study, experiments were carried out in pilot-scale water distribution systems with an 80 m long loop(150 mm diameter) made from ductile iron; all were equipped with a recirculation pump and a heat exchanger cooling system [4]. The configurations of the system [4] are presented in Figure 1.…”