| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the generation of a large quantity of sludge caused by the addition of a large quantity of a flocculant and to eliminate fear about health trouble due to aluminum by filtering a water to be filtered with a biological contact filer pond, in which a hollow filter medium and a filter medium composed of a ceramic are packed respectively in the upper bed and in the lower bed, and then, filtering it with a sand filtration or membrane filtration. SOLUTION: As for a city water treatment, at first a flocculant and an alkaline agent are added to a raw water supplied from a raw water tank, the result is stirred quickly in a quick stirring pond 2 and is slowly stirred in a floc forming pond 3 to form a floc. Next, a filtrate after forming the floc is biologically filtered in a 1st biological contact filter pond 4. In such a case, a suspended material in the water to be treated is deposited on the filter medium in the upper bed 5 of the filter pond 4 and after that, a suspended material not deposited on the filter medium of the upper bed 5 is deposited on the filter medium in the lower bed 6. Next, the filtrate is biologically filtered in a 2nd biological contact filter pond 7. In the 2nd biological contact filter pond 7, a suspended material not deposited on the filter medium in the upper bed 8 is similarly deposited on the filter medium in the lower bed 9.</p> |
