| 摘要 |
PROBLEM TO BE SOLVED: To provide technique capable of utilizing flocculated sludge as resources extremely high in value in the flocculation treatment of water. SOLUTION: A tetravalent titanium ion-containing flocculant 2 is added to raw water containing a pollutant under stirring and hydrated titanium oxide flocs are formed to flocculate and separate the pollutant in raw water to obtain flocculation treated water 5 and sludge separated from the flocculation treated water 5 is dehydrated and a dehydrated cake 8 or the dried matter thereof is dissolved in sulfuric acid or reacted with chlorine or hydrochloric acid to produce titanyl sulfate or titanium tetrachloride 11. It is also possible that the dehydrated cake 8 or the dried matter thereof is mixed with a titanium- containing raw material substance and the resulting mixture is reacted. An inorg. flocculant containing tetravalent titanium ions is pref. titanium tetrachloride and/or titanyl sulfate.
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