This study investigated the use of industrial packing material for increasing the hydraulic efficiency of small‐scale, chlorine contact tanks used in drinking water treatment. The packing material used in this study was spherical, with porosities between 0.9 and 0.95 and a density less than that of water. A total of 67 tracer studies, conducted on laboratory‐scale chlorine contact tank systems, examined three sizes of packing material, two tank sizes, and two flow rates. Sodium chloride solution was injected as a continuous tracer at the inlet and was monitored in the tank outflow through electrical conductivity. Several studies were validated with the use and direct measurement of a lithium ion tracer. Hydraulic efficiency was measured by determining the baffling factor as outlined by the US Environmental Protection Agency. Results suggest that the use of packing material in small drinking water contact tanks can significantly increase the baffling factor, improving the disinfection efficiency obtained from existing tanks.
Transitions in flow regimes that can occur in drinking water contact tanks may significantly affect the disinfection efficiency of the system. To demonstrate these effects, the authors investigated the internal velocity fields and flow regime of a drinking water contact tank located in Jamestown, Colo. The baffling factor (BF) of the system fluctuated annually between 0.5 and 0.6 because of a shift in flow regime caused by changes in the flow rate of the system. The authors studied the effects of the regime change from laminar to turbulent flow (or vice versa) using computational fluid dynamics (CFD) models and physical tracer studies. Several inlet modifications were then investigated using CFD to determine which alteration would be most beneficial. Key findings showed that with proper inlet modification, the BF of the system could be stabilized at 0.6 during periods of high or low flow.
In response to unprecedented urban and population growth and related strain on stormwater collection systems, smart‐water‐network modeling technology helps manage and reduce the risks of urban runoff.
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