A treatment method of waste water from incineration plant

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PURPOSE : To provide a wastewater treatment method for maintaining fluorine concentration to an environment regulation value 15 ppm or less while minimizing use of a fluorine removal agent comprising an expensive rare earth compound as a principal component. CONSTITUTION : A treatment method of wastewater discharged from incineration plant comprises : a heavy metal removal process comprising a step(1) of changing wastewater containing heavy metals and fluorine into acidic wastewater having pH of about 4 using sulfuric acid, a step(2) of changing the acidic wastewater into alkaline wastewater having pH of about 10.5 using calcium hydroxide, a step(3) of immobilizing heavy metals in wastewater using a heavy metal stabilizer, a step(4) of changing the heavy metal immobilized wastewater into neutral wastewater having pH of about 7 using aluminum sulfate and injecting calcium chloride into the neutral wastewater at the same time, a step(5) of injecting a polymer coagulant into calcium chloride injected neutral wastewater, and a step(6) of removing sludge produced in a settling tank; and a fluorine removal process comprising a step(7) of changing the wastewater passing through the heavy metal removal process into acidic wastewater having pH of about 4 to 5 using sulfuric acid, a step(8) of injecting a fluorine removal agent containing a rare earth compound as a principal component into the acidic wastewater, a step(9) of changing the fluorine removal agent injected acidic wastewater into neutral wastewater having pH of about 7 using calcium hydroxide, a step(10) of injecting a polymer coagulant into the neutral wastewater, and a step(11) of removing sludge produced in a settling tank. © KIPO 2006