AWWA WQTC57130

Arsenic can be effectively removed from water by sorption to amorphous or granular iron or aluminum oxides, however, silica is known to interfere with arsenic sorption at pH > 7.5. The goal of this work was to examine arsenic sorption to amorphous and granular media oxides at various levels of silica, calcium, and pH, and to closely monitor the kinetics of key reactions that occur in these systems. At pH 8.5, calcium dramatically improved arsenic sorption to amorphous iron hydroxide in the presence of silica over short reaction times, but had no long-term advantage. This result could have considerable applications for coagulation processes. Additionally, batch tests indicated that activated alumina granular media was more sensitive to water quality than granular ferric hydroxide, however, relatively low levels of calcium essentially eliminated silica interference to arsenic sorption onto activated alumina. Includes 22 references, tables, figures.