Backwash method of membrane module for turbidity internal pressure type divided by the flow rate and pressure fluctuations

摘要

PROBLEM TO BE SOLVED: To improve back washing efficiency and lower the frequency of washing with a chemical agent by repeating operations of high speed circulation washing and circulation stop or operations of high speed circulation washing and low speed circulation washing in the membrane back washing process in membrane module filtration carried out by using an inner pressure type hollow fiber membranes. ;SOLUTION: In this method comprising a back washing process for back washing an inner pressure type hollow fiber membrane module 5 for removing pollutants with back washing water in the presence of a sterilizer after a filtration process for providing filtered water from raw water by the membrane module 5, during the operation for switching the filtration process to the back washing process, an acid and/or a sterilizer to be used as an oxidizing agent are injected to a raw water flowing-in pipeline system 10 or a raw water circulation pipeline system 12 from respective storage tanks 8, 9 in order to accelerate decomposition and separation of pollutants and organic matters adhering to the membrane. Then, operations of high speed circulation washing and circulation stop or operations of high speed circulation washing and low speed circulation washing are repeatedly carried out to efficiently discharge and remove pollutants and organic matter in the inside and the outside of the hollow fiber membranes.;COPYRIGHT: (C)1999,JPO