remediation of earth resources contaminated with arsenic using soil washing technique

development of industrial activities around the world, especially during the last decades has resulted in environmental pollution rising. soil pollution is always considered as one of the most dangerous environmental threat for human’s life, fauna and flora. heavy metals such as arsenic are potential hazardous elements in generating the soil pollution. these materials could be entered into the body through different routes and cause significant adverse effects. in this study, the efficiency of soil washing technique in removing the contaminated soil resource with arsenic has been investigated.the research was conducted by collecting soil samples from a power plant site in tehran, iran. the tests were conducted in three flushing sequences of 2 hr, 4 hr and 6 hr and ph values of 12.7, 6.9 and 2.3. moreover, an eight percent solution of methanol was used throughout the experiments to treat the samples. the results of this study demonstrate that at 25°c, the average removal efficiencies of 73%, 63% and 55%, were achieved in various alkaline, neutral, and acidic environments, respectively. for 50°c, under the similar conditions, however the average removal efficiency values were 78%, 72%, 67%, accordingly, thus indicating the higher arsenic removals at higher temperature of 50°c. moreover, the analyses of soils denoted that the optimum flushing sequence for the samples was achieved at 4 hr after starting the experiments.