No 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).

This field study was conducted to explore the spatial and seasonal changes in total phosphorus and fraction distribution in relation to land uses. Water samples were collected biweekly at four sampling locations, which represented different potential phosphorus sources along the Upper Peruque Creek in Eastern Missouri. Total phosphorus concentrations of .0.8 mg/L appeared sporadically at site 2, downstream of a small community, with an average of 0.82 6 0.14 mg/L in fall. Particulate phosphorus accounted for approximately 80% of total phosphorus at all sampling sites, except for site 2, where approximately 50 to 75% of dissolved phosphorus was often observed. Approximately 71 and 85% of total phosphorus in the sediment was in the form of iron(III) phosphate at the headwaters and downstream sites, respectively; 29 and 15% was in the form of phytic acid at the two sites. Land uses affect the total phosphorus concentration and alternate phosphorus fraction and speciation in the creek. Water Environ. Res., 80, 316 (2008).