Arsenic contamination of soil and arsenic removal from groundwater in Bangladesh

摘要

We have investigated arsenic contamination of groundwater in Samta and Mama villages in Bangladesh. The arsenic distributions in the soil of both villages are introduced in this paper. We developed a Pond Sand Filter (PSF) system for drinking water in 1999. We have studied applications of the PSF system to arsenic removal from groundwater. The arsenic distributions in the soil of the two villages and the performance of arsenic removal are as follows. 1) In Samta village, the muddy layer (1-15 m deep) with organic matter has higher arsenic content (more than 20 mg/kg) than the soil in other layers. In Mama village, the muddy layers (0-7 m and 40-45 m deep) and the intercalary silt and clay in the sandy layer (5-45 m deep) contain higher arsenic than other layers, also. 2) The gravel tank in the PSF system has high arsenic removal performance, decreasing arsenic from 0.2-0.4 mg/L of raw water to under 0.1 mg/L of treated water. The 1 m length of the tank with gravels of 5 mm diameter will be enough to remove arsenic at water with a water flow velocity of 1m/h. The co-precipitation was occurred very well with adequate aeration in the PSF inlet tank.