| 摘要 |
PROBLEM TO BE SOLVED: To provide a cleaning method of a floating filter medium layer capable of allowing effective backwash of the floating filter medium layer, while preventing floating filter media from flowing out of a filtration tank, in a filtration system for filtering raw water using the floating filter medium layer comprising a large number of floating filter media.SOLUTION: The cleaning method of a floating filter medium layer in a filtration system having a filtration tank including: a floating filter medium layer; a screen; a filtered water storage part; and a backwash wastewater discharge port. The cleaning method of a floating filter medium layer includes: a first backwash process of discharging water in the filtration tank from the backwash wastewater discharge port, at a flow rate where floating filter media descend; and a second backwash process of, when the floating filter media reach a predetermined position above the backwash wastewater discharge port, changing the flow rate of backwash wastewater to be discharged from the backwash wastewater discharge port, into a flow rate where the floating filter media are at a standstill or ascend. |
