Method for treating post-washing liquid in combined-soda I process by using reverse osmosis membrane technology

The invention relates to a method for treating post-washing liquid in a combined-soda I process by using a reverse osmosis technology. The discharged alkali liquid is filtered in an alkali filter, washing with washing water is carried out, the post-washing liquid is saved in a post-washing liquid storage tank, and the post-washing liquid is discharged from the post-washing liquid storage tank andtreated with a multi-stage filtering device. Ultrafiltration, reverse osmosis and other membrane separation technologies are applied, and multistage treatment is carried out on the post-washing liquid, so that the salt content in the post-washing liquid is effectively reduced, and the treated post-washing liquid can meet the index requirements of washing water. The post-washing liquid treated by the process can be directly used as washing water to be applied to an alkali filter, so that the use amount of the washing water in the process is greatly reduced, and the risk of mother liquor expansion of a combined-soda sys