摘要 |
Using the filter auxiliary agent separated by backwashing from a filter element repeatedly and effectively, the consumption amount of a filter auxiliary agent and the generation of industrial waste can be suppressed. In a filter auxiliary agent pre-coat circuit, a filter auxiliary agent in a pre-coat tank is attached and stacked on a filter element in a filter case, and a filter auxiliary agent layer is formed. In a filter circuit, the filter auxiliary agent layer of the filter element removes sludge in the filter treatment liquid in a main tank. A backwashing circuit breaks down the filter auxiliary agent layer and a sludge layer, separates the filter auxiliary agent layer and the sludge layer by backwashing from the filter element, and circulates to the pre-coat tank. After repeating these steps a plurality of times, the filter auxiliary agent and sludge separated by backwashing are taken out to the exterior.
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