Abstract
The high arsenic content in groundwaters of Kandal province, Cambodia has threatened about 1 million people with tens of them being at risk to arsenicosis. In this context, this study aims to investigate the removal of arsenic from Kandal groundwater by utilizing naturally available laterite from Kampong Cham province in order to obtain safe drinking waters for the people. The laterite samples were characterized with XRD, XRF, zeta potential analyzer, and surface area analyzer. Batch adsorption experiment of As(V) onto laterite was conducted under ambient temperature as a function of adsorbent dose, contact time, initial As concentration, solution pH, and coexisting phosphate concentration. Surface complexation modeling (SCM) was also performed in order to interpret the experimental results. The experimental results showed that 12.5g/L laterite could reduce arsenic to a level below the Cambodian guideline (50μg/L) within 40 minutes of contact time at neutral pH. The presence of phosphate in groundwater was insignificant in the decrease in arsenic removal. The results of SCM coupled with the experimental data indicate that most of adsorption behavior of arsenic onto the laterite such as dose, pH and phosphate effects would be attributed to iron minerals rather than other constituent minerals (i.e. quartz and kaolinite) in the laterite. Moreover, the minimum dose of laterite to completely adsorb 1.5mg/L arsenic was only 〜0.13g/L. This implies that only 1kg laterite is needed per year if 19.8 liters of water is required per day by a small family in Kandal province. Hence, the field applicability and availability of laterite in Kampong Cham must be considered to remove arsenic from groundwaters for the residents of Kandal province.
