DEVELOPMENT AND EVALUATION OF SAND FILTRATION PROCESSES FOR THE TREATMENT OF ARSENIC-POLLUTED GROUNDWATER IN BANGLADESH

Arsenic contamination of groundwater is found to be one of the most serious problems Bangladesh and surrounding region. This research report aim to investigate the removal mechanism of arsenic in oxidation-sand filtration process installed in a small community in Bangladesh. In order to remove arsenic at satisfactory level, the existence of iron with arsenic is found to be very important. Low concentration of iron may results unsatisfactory arsenic removal efficiency. Laboratory experiment exhibited that arsenic associated with small particles of iron hydroxide was the major species of arsenic released from the filter. This phenomenon is the major mechanism of leakage of arsenic from sand filters. In the sand filtration system, up-flow filtration was more effective than down-flow filter.