AWWA WQTC60738

Recent pilot trials from the southwestern United States indicated decreased treatment capacities by 90 % of iron based adsorbents in the presence of high silica concentrations. Laboratory scale column tests gave great variations of the effluent concentrations and final capacities. In most tests with high raw silica concentrations, the capacities were higher compared to the US pilot trial, but lower than with low silica concentrations Chemical methods of washing and backwashing the media with spiked solutions, or conditioning the media with oxidants are problematic with respect to the ease of operation of the process. A new type of iron based adsorption media has been synthesized which has less sensitivity against silica adsorption and precipitation while keeping its arsenic adsorption capacity. Includes 4 references, tables, figures.