METHOD FOR RECOVERING DISSOLVED IRON FROM WASTEWATER CONTAINING MANY KINDS OF METAL ION
PROBLEM TO BE SOLVED: To provide a method for recovering dissolved iron in waste water, by which the interfusion of components other than iron is suppressed, moreover, sludge having low water content and excellent dewaterability can be obtained and dissolved iron in wastewater can be recovered and u...
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Zusammenfassung: | PROBLEM TO BE SOLVED: To provide a method for recovering dissolved iron in waste water, by which the interfusion of components other than iron is suppressed, moreover, sludge having low water content and excellent dewaterability can be obtained and dissolved iron in wastewater can be recovered and used, when the raw water is wastewater containing many kinds of metal ions mainly including dissolved iron particularly ferrous iron.SOLUTION: The raw water is introduced into a neutralization oxidation tank, pH of the raw water is adjusted between 3.5 and 6.0, δ-FeO(OH) is added into the neutralization oxidation tank as a catalyst, dissolved iron is subjected to oxidation treatment by an oxidizing agent to produce metal hydroxide mainly including iron(III) hydroxide particles and then metal hydroxide-containing sludge is separated by precipitation in a precipitation tank arranged at a downstream side of the neutralization oxidation tank and further a return process for returning a part of the sludge separated by precipitation to the neutralization oxidation tank is provided. In that process, a part of the sludge separated by precipitation is introduced into a sludge reaction tank, the sludge is treated by adding an alkali agent into the reaction tank and the raw water is continuously treated while returning treated sludge into the neutralization oxidation tank. Thus the method for recovering dissolved iron from wastewater containing many kinds of metal ions is provided. |
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