FILTERING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a filtering device that enables suppression of decline in a service life of a filtration tank and reduction in frequency of stopping supply of filtrated liquid.SOLUTION: A filtering device 100 includes: a calculation part 30 for calculating the trapped amount of impurities trapped by a filtering medium in one cycle of a filtering operation; a storage part 29 for storing a plurality of threshold values that are set based on a concentration of the impurities in raw water L1 and a flow rate of the raw water L1 flowing inside a filtration tank 102 and are used for switching from the filtering operation to a backwashing operation; and a control part 27 that selects a threshold value corresponding to the flow rate of the raw water L1 flowing in the filtration tank 102 during the filtering operation and the concentration of the impurities from the plurality of threshold values stored in the storage part 29 and that performs control so as to enable transition from the filtering operation to the backwashing operation on the basis of a situation where a detection result from the calculation part 30 reaches the selected threshold value.