AWWA JAW24448 ✓ Most Recent

Laboratory and pilot-plant studies were conducted to define the optimum conditions for manganese removal and washwater recovery at the Serra Azul direct filtration plant in Belo, Horizonte, Brazil. The inverted sequence of chemical addition recommended - chlorine-ferric chloride-lime - offers definite advantages for manganese oxidation. Neither the use of polyelectrolytes nor the recycling of filter washwater was found to be advantageous. Changing the existing deep beds to the optimized shallower beds with coarse media will facilitate washing of filters. Wash rates that are higher than those originally designed are necessary to adequately clean the filters. Adding anionic polyelectrolyte was observed to improve the settling and specific resistance of the sludge but did not increase thickened or filter cake sludge concentrations. The washwater will be recovered using combined equalization-settling tanks, and the sludge will be dried in lagoons. Includes 11 references, tables, figures. See more