| 摘要 |
<p>A coagulation precipitator having a coagulation precipitation section provided with a contact material-accumulated layer (84) formed by accumulating small pieces of a contact material of a high prosity, raw water to which a coagulant is added being supplied upstream to the coagulation precipitation section to coagulate the suspension in the raw water and precipitate the coagulated suspension, wherein the coagulation precipitator is provided with a prestage coagulation section as a pretreatment section having at least one contact material-accumulated layer (82) through which the raw water is passed at a superficial velocity higher than that in the contact material-accumulated layer in the coagulation precipitation section, primarily treated water being discharged from the prestage coagulation section with the coagulated flock produced in the contact material-accumulated layer, to be supplied into the coagulation precipitation section, whereby a frequency at which to carry out a cleaning operation can be reduced while the treated water is maintained at a low turbidity.</p> |
