Method for cleaning separation membrane module, and method for fresh water generation

• Main Authors: IKEDA, KEIICHI, ONISHI, TAKASHI, OKUBO, KENICHI
• Format: Patent
• Language: English
• Published: 16.01.2014
• Subjects: CHEMISTRY; METALLURGY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; TRANSPORTING; TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE

Disclosed is a method-for cleaning a separation membrane module after raw water containing particles that have a higher hardness than the separation membrane are percolated using the separation membrane-wherein, with the aims of efficiently decreasing abrasion of the outer membrane surface resulting from the high-hardness particles during air washing, suppressing cake filtration resistance deriving from high-hardness particles on the membrane surface when the membrane continues to be used in a percolation step, and enabling stable operation at a low membrane percolation pressure differential, after ending percolation, after water on the primary side of the membrane within the separation membrane module is discharged out of the system, back-pressure cleaning is conducted, during which the back-pressure cleaning wastewater within the separation membrane module is discharged, and then one of the belowmentioned steps is conducted, after which the water on the primary side of the membrane in the separation membrane module is discharged out of the system: (a) a step wherein the primary side of the membrane in the separation membrane module is filled with water and air washing is performed; (b) a step wherein air washing is performed while supplying water to the primary side of the membrane within the separation membrane module.