To effectively use sludge after magnetic separation at a high speed and at low cost by adding magnetic powder such as triiron tetroxide and ferric polysulfate solution as coagulant from a chemical injector to raw water and agitating the mixture in an agitating tank to produce pretreated water containing magnetic aggregate.
Raw water in a reservoir 1 is passed from a conduit 2 through a filter 3 for removing large refuse. First it is stored in a raw water storage tank 5 by a pump 4, and then magnetic powder such as triiron tetroxide and ferric polysulfate solution are added as coagulant from a chemical injector 7 to the raw water, and the mixture is agitated in an agitating tank 9 to produce pretreated water containing magnetic aggregate. The magnetic aggregate is separated and captured from the pretreated water by a magnetic separator 30, and the purified raw water is stored in a treated water tank 23 and is returned to the reservoir 1. By this way, sludge after magnetic separation can effectively be used at a high speed and at low cost.
ISOKAMI HISASHI
MORITA MINORU
HANDA FUMITAKA
OKAJIMA HIROAKI
HITACHI TSUCHIURA ENG KK