| 摘要 |
In a method for cleaning a membrane module including at least one of a microfiltration membrane and an ultrafiltration membrane through which raw water is membrane-filtered to obtain membrane filtrate, for effectively cleaning a membrane module with reducing a drop in water recovery ratio and the cost of chemicals by preventing a chemical from leaking out to and remaining on the filtrated side of the membrane module after a cleaning step, a chemical diffusion step in which chemical-containing water is fed to a feed side of the membrane module and diffused from the feed side of the membrane module to a filtrated side of the membrane module is performed, and subsequently a backwashing step in which the membrane module is backwashed by allowing the membrane filtrate to flow from the filtrated side to the feed side of the membrane module is performed, in which, in the chemical diffusion step, an execution time of the chemical diffusion step is controlled based on a concentration of the chemical diffused to the filtrated side of the membrane module. |
