Adsorptive contactors for removal of soluble manganese during drinking water treatment

Many water utilities historically have produced highly effective manganese (Mn) removal by maintaining an active manganese dioxide (MnO(x(s))) surface on their filter media that adsorbs soluble Mn. This process requires the presence of free chlorine to regenerate the media or the system fails, and some utilities have ceased adding free chlorine before their filters to pursue treatment goals such as disinfection by-product control or biological filtration. Often the result is elevated Mn levels in the finished water and a corresponding increase in consumer complaints. This research demonstrated the use of MnO(x(s))-coated media as a postfiltration adsorptive contactor to provide cost-effective, efficient soluble Mn removal across a range of hydraulic loading rates, solution pH, influent Mn levels, and hypochlorous acid concentrations. Integration of the technology into treatment plants via either new design or retrofit could provide effective Mn control, especially at facilities seeking to eliminate free chlorine application to dual-media filters and/or establish biofiltration across the filters.