Temperature dependence for purification of leachate containing heavy metals by phytoremediation using the artificial channel

Concentrations of heavy metals leach from soil and rock excavated at civil engineering construction sites occasionally exceed the environmental criteria value in Japan. The phytoremediation is one of the techniques for cleaning up contaminated environments. The Eleocharis acicularis is tolerant plant of a wide variety of heavy metals, and it absorbs and accumulates these metals and has been proven to be effective in mine effluent treatment. In this study, we conducted a purification experiment using an artificial channel to know the ability of the E. acicularis to absorb and accumulate heavy metals due to differences in temperature. The drainage containing arsenic flowing out of the embankment flowed into the artificial channel at different periods of average temperature. As a result of experiments, the arsenic content of the E. acicularis were confirmed increasing in 3.4 mg/kg in the summer and 2.3 mg/kg in the winter. These values are corresponding with 0.8% in the summer and in 0.3% in the winter for the arsenic gross weight of the displacement according to each season. Thus, the arsenic absorption ability of the E. acicularis was able to grasp by the artificial channel experiment.