According to the method, when the concentration of
sodium sulfate decahydrate and
sodium sulfite heptahydrate in
wastewater is nearly saturated, pure
sodium sulfate hydrate mixed salt can be separated out by
water cooling at the temperature of 10-25 DEG C, so that pure
sodium sulfate and
sodium sulfite hydrate mixed salt crystals are obtained; organic matters adsorbed on the surface of the
hydrate mixed salt are eluted and decolored in a manner of washing with dilute alkali liquor, and the
sodium sulfate hydrate mixed salt subjected to alkali washing and decoloring completely meets the technical index requirements for preparing
anhydrous sodium sulfite / sodium pyrosulfite; according to the method,
naphthalene sulfonic acid organic matters are separated from alpha / beta
naphthalene sulfonate,
sulfone and other organic matters (TOC) contained in
wastewater through heat preservation and
filtration by utilizing the characteristic that the
solubility of the organic matters in nearly saturated
saline water is extremely low; therefore, after the organic
wastewater containing
sodium sulfate,
sodium sulfite and other salts can be repeatedly evaporated and concentrated to be nearly saturated, pure and decolored sodium
sulfate hydrate mixed salt and low-salt
naphthalene sulfonic acid organic matters are separated from the wastewater by adopting the
modes of insulating and filtering to remove organic matters, water-cooling to separate out salt and alkali washing; after the process scheme is industrially implemented, the naphthol wastewater treatment can avoid the traditional treatment method for removing organic matters by resin adsorption or extraction, and sodium sulfate mixed salts and naphthalene
sulfonic acid organic matters in the wastewater are directly purified, so that the wastewater treatment cost and investment are greatly reduced; according to the process
route, the
bottleneck problem of high treatment cost of the naphthol wastewater is solved, and resource recycling of the wastewater and the waste salt is realized.