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.
A novel approach using a hybrid combination of internal baffles and industrial packing material is investigated in order to optimize the hydraulic residence time of a 1,500‐gal rectangular concrete tank. Hydraulic residence time, which is commonly classified using the baffling factor (BF), was determined from residence time distribution curves obtained using both computational fluid dynamics (CFD) simulations and physical tracer studies. CFD simulations were used to model two scenarios. The first scenario was a base system consisting of an unbaffled concrete tank, and the second scenario was a two‐baffle system. Computational simulation results were experimentally validated via tracer studies on a full‐scale prototype. Modifications to the two scenarios were then experimentally implemented by locally placing random packing material at regions of high velocity and flow separation. Associated results highlight that the hybrid combination of baffling and packing material yielded substantial gains in the BF over systems using only internal baffles or only inlet modification.
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