| 摘要 |
<p>PURPOSE:To reduce the amount of a coagulant for removing suspended substances and to prevent the generation of odorous components by installing an oxidation means which keeps return sludge in an optimum environment for aerobic microorganisms contained in the sludge for a specified length of time and an acid addition means for ionizing Al(OH)3 contained in the return sludge. CONSTITUTION:In an agitation tank 2, suspended substances in raw water are coagulated by the addition of a coagulant containing an Al-component. In a coagulation-precipitation tank 3, the coagulated suspended substances are precipitated to be separated from treated water 18, which is led to a treated water system, and the precipitated sludge is recovered. In a coagulated sludge concentration tank 5, a part of the recovered sludge is returned to the agitation tank 2. An aeration tank 8 as an oxidation means which keeps the return sludge in an optimum environment for aerobic microorganisms contained in the sludge for a specified length of time, a blower 9, an acid addition pump 11 as an oxidation means for ionizing Al(OH)3 contained in the return sludge, and an agitator 13 are installed in this order in the sludge returning system.</p> |
