PURPOSE: To eliminate the clogging of the porous tube filter used in the filtering of a protein-containing solution, by contacting said tube filter with an aqueous solution containing alkali before washing the same with pressurized water.
CONSTITUTION: The tube wall of a clogged porous tube filter is contacted with an aqueous alkali solution so as to be immersed in said solution or to flow the same through the tube wall. A yellowish brown solution is liberated from the tube wall by the contact with the aqueous alkali solution. Prior to washing by pressurized water, the tube wall is washed with compressed gas. The washing by compressed gas is performed by allowing said gas to pass through the tube wall in the direction reverse to a filtering direction and the precipitate softened by alkali washing is separated, released and blown off. Next pressurized water is allowed to pass the tube wall in the direction reverse to the filtering direction to perform backwashing end the precipitate dispersed or softened by alkali washing or the precipitate by gas washing is washed off.
YAMADA SADAO
AKIMOTO NAOYUKI
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