| 摘要 |
PROBLEM TO BE SOLVED: To provide an economically excellent treatment system which efficiently removes selenium and cadmium from heavy metals-containing water in which a plurality of heavy metals, for example, selenium and cadmium, coexist. SOLUTION: In treatment method where the heavy metals-containing water receives addition of a reducing iron compound and then is introduced into a closed reaction tank, and alkaline sludge with a pH of 11-13 is added thereto to adjust the pH inside the tank to 8.5 or more, thereby generating a precipitate containing green rust and iron ferrite in an non-oxidizing atmosphere, the pH of the water containing heavy metals, for example, selenium and cadmium, in a first reaction tank is adjusted to 8.7-9.3 to precipitate selenium, and then the pH of the water in the second reaction tank is adjusted to 9.5-10.5 to precipitate cadmium, thereby reducing both the selenium concentration and the cadmium concentration in the treated wastewater to less than 0.01 mg/L. COPYRIGHT: (C)2009,JPO&INPIT
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