Arsenic and Fluoride Removal Using Simple Materials

Since many at risk to arsenic and fluoride contamination cannot afford or do not have access to modern, centralized water treatment facilities, simple and low-cost solutions must be found. Bone char, goethite coated sand (G-IOCS) and hematite coated sand (H-IOCS) were evaluated for treating water with elevated levels of arsenic and fluoride present individually or together. Results obtained were compared to conventional media used in developed countries; activated alumina and granular ferric oxide. Fluoride adsorption capacity was higher in bone char than in G-IOCS and H-IOCS. Fluoride removal was not affected by the presence of environmentally significant arsenic (III) and arsenic (V) concentrations. On a mass basis, bone char's fluoride adsorption capacity was comparable to that of activated alumina both in the presence and absence of 0.25 mg/L of arsenic (III) and arsenic (V) in solution. Bone char also showed higher capacity to remove arsenic (III) and arsenic (V) from solution than both G-IOCS and H-IOCS, likely due to its much higher surface area. The 10 mg/L of fluoride did compete with arsenic (V) for adsorption onto the bone char. Both G-IOCS and H-IOCS removed arsenic (III) from solution even in the presence of fluoride; however, G-IOCS had higher arsenic (III) adsorption capacity than H-IOCS, possibly as a result of higher surface area of goethite coated onto the sand. On a mass basis, the bone char and iron oxide coated sands were two to three orders of magnitude less efficient in removing arsenic (III) and arsenic (V) than a commercially produced granular ferric oxide.