Abstract
Drainage water from dumping site of waste soil from tunnel excavation work for transportation network building some time contains higher concentration of arsenic than its environmental standard. For arsenic removal from the contaminated water, technologies such as ion-exchange and flocculation precipitation treatment have been developed and applied, but the high cost of the treatment and production of secondary waste still cause problems to be solved. In this research, a low cost arsenic purification method by using arsenic hyperaccumulator plant Pteris vittata was developed. Hydroponic purification pilot plant experiment by using P. vittata for removing arsenic from drainage was set in the tunnel excavation soil landfill site in Sendai, Japan. Drainage from this landfill site contained 20~30 μg/L arsenic and its pH was alkaline (around pH 9). After 3 months P. vittata hydroponics treatment of the drainage water from the soil dumping site, arsenic concentration of the treated drainage water was lowered to below 10 μg/L and pH also was lowered to 8.3 that clears its environmental standard. From these results, we concluded that hydroponics purification technology by using arsenic hyperaccumulator plants for arsenic removal is effectively applicable as a lowcost purification of arsenic contaminated drainage water from soil dumping sites.
