Abstract： In order to improve the batch intermittent operation mode of nanofiltration membrane system in the process of alkali recovery of viscose staple fiber production, a continuous membrane treatment method was developed by using the six stage nanofiltration membrane system for progressive circulating filtration and combined with DCS control system. When the flux of a certain stage of nanofiltration membrane decreases and needs to be cleaned, of this stage nanofiltration membrane module can be switched out of the nanofiltration membrane system for cleaning, and other stages of nanofiltration membrane module operate normally to achieve the purpose of cleaning the nanofiltration membrane without stopping the machine. The results showed that after the continuous membrane treatment, the semi fiber content of the clean liquid produced by the alkali squeezing liquid was ≤ 5 g/L, and the semi fiber content of the concentrated liquid was 70~75 g/L, which could be recycled to the production system to mix impregnated alkali and dissolved alkali. Compared with batch intermittent operation mode, the cleaning times of the nanofiltration membrane system can be reduced by 2~3 times per day, and the treatment capacity of a single membrane can be increased by 1.2 times.
