FILTRATION MEMBRANE CLEANING METHOD AND MEMBRANE FILTRATION APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a membrane filtration apparatus and a filtration membrane cleaning method, enabling a filtration membrane to be efficiently and stably operated in a long term.SOLUTION: The membrane filtration apparatus and the filtration membrane cleaning method are provided. The filtration membrane cleaning method is provided for cleaning a filtration membrane module comprising: a filtration membrane 10 which removes contaminant including at least soluble organic substance or turbid matter in raw water to obtain membrane filtration permeated water; a raw water inlet 10c located on the raw water side of the filtration membrane; a cleaning water introduction port 10e disposed in a bottom part of the filtration membrane module; and a cleaning waste water outlet 10f disposed on an upper part of the filtration membrane module. The membrane filtration apparatus and the filtration membrane cleaning method each concurrently perform the following two steps: a reverse cleaning step (1) of causing filtration membrane permeated water to flow as reverse cleaning water to the raw water side from the permeated water side of the filtration membrane; and a fine air bubble cleaning step (2) of causing fine air bubble-mixed cleaning water to flow along the filtration membrane and discharging the fine air bubble-mixed cleaning water from a cleaning waste water outlet, the fine air bubble-mixed cleaning water being obtained by mixing nano-bubbles having a diameter of 1 μm or less and micro-bubbles having a diameter of 1 to 5 μm into the raw water side from the cleaning water introduction port.SELECTED DRAWING: Figure 2