A method and system for cleaning and filtering lye nanofiltration membrane

Abstract

The invention relates to a method and system for cleaning and filtering alkali liquid nanofiltration membranes. The cleaning method comprises the following steps: using soft water to circulate and rinse the nanofiltration membranes until the pH value of the primary flushing liquid at the outlet of the nanofiltration membranes is neutral, draining Empty the first flushing liquid; rinse the nanofiltration membrane with acid solution for the second cycle until the pH value of the secondary flushing liquid is stable at 1-1.5, and then drain the secondary flushing liquid after 30 minutes of recirculation flushing; use soft water for three cycles Rinse the nanofiltration membrane until the pH value of the three rinses at the outlet of the nanofiltration membrane is greater than 6, and empty the rinses three times; wash the nanofiltration membrane with lye four times, and after 15 minutes of circular washing, drain the rinses four times, Cleaning is over. The present invention uses soft water, a certain concentration of acidic solution and a certain concentration of alkaline solution to clean the filter lye nanofiltration membrane in stages, remove the impurities trapped in the flow channel and pores of the nanofiltration membrane, change the cleaning method of the nanofiltration membrane, and recover The filtration capacity of nanofiltration membrane prolongs the service life of nanofiltration membrane and reduces operating costs.

Description

technical field [0001] The invention relates to a cleaning method and system, which are applied in the production process of viscose staple fiber, and in particular to a method and system for cleaning and filtering lye nanofiltration membranes. Background technique [0002] At present, domestic viscose staple fiber production enterprises generally use nanofiltration membrane system to filter and remove hemicellulose in lye in the process of lye filtration, reduce the content of hemicellulose, and recycle lye. When using nanofiltration membrane filtration equipment, after the equipment is put into use for a certain period of time, impurities and macromolecular substances in the lye will stay in the flow channels and pores of the nanofiltration membrane, thereby reducing the filtration capacity of the nanofiltration membrane. When the filtration capacity of the nanofiltration membrane cannot meet the production requirements, it is necessary to clean the nanofiltration membrane...

AI Technical Summary

Problems solved by technology

In the production process of viscose staple fiber, the method of cleaning and filtering the lye nanofiltration membrane mainly adopts the traditional hydraulic method or alkaline solution cleaning method. At present, this cleaning method is time-consuming and laborious, and requires more water or alkaline solution. There is no clear instruction on the cleaning results due to continuous long-term flushing, and experience judgment is needed when it ends, and the cleaning effect is average, but the cost is high

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