| 摘要 |
PROBLEM TO BE SOLVED: To rapidly purify and drain water by filtering the turbid water of a septic tank when the turbidity of this water attains a prescribed value or above. SOLUTION: At the time of draining the turbid water after lowering the concn. of BOD, COD, etc., of the turbid water, the org. matter of the stored liquid is made into sludge by a purifying device 400 in order for the turbid water to attain the prescribed turbidity. Only the purified water is sucked by a drain pump 414 via hollow membranes 413 and is brained. At this time, the turbid water stored in this purifying device 400 is filtered by a filter device 430 in such a case the sludge concn. of the purifying device 400 is high and the purification time takes long or in other cases. The filtration is executed by using chips, etc., in such a manner that the sludge is adhered to the chips. The filtered liquid is decided to be insufficiently filtered if the turbidity of the filtered liquid is above the prescribed value of above. The purified water is then returned to the purifying device 400 by a circulating device 460. The purified water is drained in the case the turbidity is above the prescribed concn. |
