Method for treating waste liquid generated in production of 5-sulfoisophthalic acid monosodium salt

The invention discloses a method for treating waste liquid generated in the production of 5-sulfoisophthalic acid monosodium salt. The method comprises the steps of uniformly collecting waste liquid generated in the production process of 5-sulfoisophthalic acid monosodium salt into a waste liquid storage tank through a pipeline; transferring a certain volume of waste liquid from the waste liquid storage tank into an extraction kettle, adding acid or alkali to adjust the pH value to 0.2-0.6, and adding an extraction agent for extraction; transferring the extracted organic phase into a back extraction kettle, adding a back extraction agent, uniformly stirring, opening a vacuum pump, heating to 60-70 DEG C, stopping heating when a solid is separated out from the back extraction kettle, and cooling to obtain a recovery liquid and a crude product; and mixing the crude product with an intermediate product in the production process of 5-sulfoisophthalic acid monosodium salt, and carrying out purification treatment t