ASSESSING THE EFFECTS OF STORAGE TANK DESIGN ON WATER-QUALITY

A study was conducted to assess the effects of storage tank design and operation on mixing regimes and effluent water quality. The influent and effluent flows of three tanks with diameter-to-height ratios rangi ng from 3.5:1 to 0.4:1 were monitored for chlorine residual. Chlorine levels were also measured within the water column of each tank. Althou gh chlorine profiles revealed some stratification in tanks with large height-to-diameter ratios, completely mixed models were more accurate than plug-flow models in representing the mixing behavior of all three tanks. Modeling further indicated that the quality of the effluent fr om completely mixed tanks deteriorated with decreasing volumetric chan ge. Standpipes were the least desirable tank design with respect to ef fluent water quality.