AWWA WQTC60626

The majority of municipal water treatment plants in the United States utilize groundwater for their public drinking water supply. To meet capacity and quality requirements, a number of communities utilize deep wells which pass through soils that contain radionuclides. Many times, the radium concentration in the water from these deep wells exceed the US Environmental Protection Agency Maximum Contaminant Level (MCL) of 5.0 pCi/l (picocurries/liter) for combined radium 226 and radium 228. Radium has been shown to be effectively removed through a number of treatment processes including ion exchange, lime softening, reverse osmosis and Hydrous Manganous Oxides (HMO) treatment. HMO treatment has shown to consistently remove 60-80 percent of the radium from the raw water. With proper chemical dosages and detention time, removal rates of over 90 percent are possible. A byproduct of radium degradation is gross alpha which currently has an MCL of 15 pCi/l. HMO treatment has also been proven to substantially reduce gross alpha concentrations to meet MCL levels. This paper details the design considerations of HMO treatment for radium reduction. Details discussed include pilot and full scale design and operation, waste disposal considerations, effects on final water quality, and summary of target water conditions. A case study of a full scale system operating for 10 years is also included. Includes 4 references, figures.