Arsenic removal from drinking-water by coagulation: the role of adsorption and effects of source water composition

Abstract

In many areas of the world, notably the West Bengal region of India (Das et al., 1994; Chatterjee et al., 1995), south-western Taiwan (Shen, 1973; Hricko, 1994), and Inner Mongolia, China (Hricko, 1994; Niu et al., 1995; Luo et al., 1995), elevated concentrations of arsenic in drinking-water have resulted in symptoms of chronic arsenic poisoning in local populations. These elevated arsenic concentrations are usually of natural origin. In areas with current or historical mining activities, however, arsenic contamination of natural waters may be associated with leaching of mine tailings or deposition of arsenic released to the atmosphere during smelting processes as has occurred in southern Thailand (Choprapawon, 1995), Ghana (Bowell et al., 1994) and the western United States (Benner et al., 1995). Mitigation of arsenic exposure in such areas primarily involves substitution of drinking-water from alternate (uncontaminated) sources, or treatment of source waters that contain arsenic well in excess of the current standards. The current standard or maximum contaminant level (MCL) in the United States is 50μg/L (50ppb); the provisional guideline value recommended by the World Health Organization is 10μg/L (WHO, 1993; Pontius, 1994).