| 摘要 |
PURPOSE:To achieve stable treatment, by returning biologically treated water to a calcium ion-containing org. sewage to mix the same with said sewage and subsequently performing solid-liquid separation. CONSTITUTION:After raw water is uniformized in a conditioning tank 1 under stirring, said water is sent to a calcium removing equipment 2 and biologically treated water is mixed with the raw water in a reaction tank 3 to form and sediment CaCO3. Further, a flocculant such as ferric chloride or aluminum sulfate is added to the raw water under stirring to send the raw water to the first floc forming tank 4 and a polymer flocculant is added to form flocs under stirring. Subsequently, the raw water is sent to the first sedimentation tank 5 and the flocs are sedimented to perform solid-liquid separation. The supernatant liquid is sent to a biological treatment equipment 6 to decompose a BOD component. By this method, economical efficiency is enhanced.
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