AWWA WQTC58900

The overall objective of this project is to establish a better understanding of the fate of manganese through water treatment and in the distribution system. A secondary objective is to assess the quality of treated water blended with membrane treated filter backwash water, simulating recycling. Even for utilities that meet the current secondary maximum contaminant level (SMCL) of 0.05 mg/L for manganese, many continue to report and experience discoloration from customers and from visible stains in the distribution system. This study analyzed Mn occurrence in a case study at a surface water utility in Dartmouth, Nova Scotia that uses chemical oxidation for Mn removal. Iron and aluminum were examined as well, as they are relevant inorganic contaminants for the utility. Treated water and water blended with membrane-treated backwash water were oxidized by a secondary disinfectant (chlorine, chloramines, chlorine dioxide or no disinfectant) and incubated for a 25-d period, simulating the time finished water might spend in the distribution system. Includes 26 references, table.