AWWA WQTC64174

This slide presentation outlines a study to develop soluble manganese sorptive contactors for enhancing potable water treatment practices. Research objectives included: demonstrate the technical feasibility of using large-size, MnO_x(s)-coated media as a post-filtration adsorptive contactor for soluble Mn control; and evaluate the process under varying conditions - media type, pH, HOCl and Mn concentrations, hydraulic loading rates. Related water treatment concerns included: problematic "in-plant" sources of soluble Mn, e.g. anoxic sedimentation solids, coagulant contamination, recycle of Mn-laden waters from solids processing systems, etc.); and, the absence of an active MnOx(s) surface and free chlorine regeneration of this surface results in treatment plants being challenged to achieve 0.015-0.02 mg/L finished water Mn levels. Topics covered include: performance of two-stage filters for soluble Mn uptake on media; adsorptive contactor characteristics; experimental parameters of interest; bench scale experimental setup; results of bench-scale column experiments; specific experimental parameter effects on process performance; pilot-scale testing; and, estimation of Mn adsorption performance of contactor media. Conclusions were that: post-filtration adsorptive contactors are a viable mechanism for soluble Mn control; contactors can be operated under high hydraulic loading rates (at or above 20 gpm/ft²) while still producing efficient Mn removal; conditions necessary for process performance include pH at or above 6.5 and the presence of a suitable free chlorine residual across the contactor; and, contactor performance is directly related to the availability of Mn sorption sites on the media. Includes tables, figures.