2-naphthol (C₁₀H₈O) is a core dye intermediate. The wastewater generated during its production has the characteristics of deep color and strong acid-base buffering capacity, with COD concentration up to 30000～40000mg/L and salt content of 10%～15%. It is rich in refractory naphthalenesulfonic acid (C₁₀H₈O₃S) and other organic intermediates, as well as inorganic substances such as sodium sulfate (Na₂SO₄), sodium sulfite (Na₂SO₃) and sodium chloride (NaCl). The wastewater has extremely poor biodegradability and toxicity to microorganisms, making conventional biochemical treatment processes difficult to meet the standard.

After dehydration by evaporator, the main component ratio of the concentrated salt residue is clear: 60%～70% sodium sulfate, 8%～12% sodium sulfite, 5%～8% sodium chloride, 3%～5% naphthalenesulfonic acid (C₁₀H₈O₃S), and the rest are a small amount of impurities. Efficient resource recovery of various materials can be achieved through refined processes such as concentration, separation, enrichment, extraction, crystallization and purification.

Organic material recovery: Naphthalenesulfonic acid (C₁₀H₈O₃S) can reach industrial grade after purification and be reused in the synthesis and production of dyes, pharmaceuticals and other fields to realize resource recycling. Inorganic material recovery: Sodium sulfate (Na₂SO₄) is purified to industrial grade, which is widely used in printing and dyeing auxiliary, detergent filling and other scenarios; Sodium sulfite (Na₂SO₃) can be used as deoxidizer and bleaching agent after recovery, adapting to the needs of textile, chemical and other industries; Sodium chloride (NaCl) is refined and used as basic chemical raw material. Only a small amount of useless impurities are disposed of in accordance with hazardous waste regulations, truly turning concentrated salt residue into treasure, greatly reducing the disposal cost of enterprises, and simultaneously highlighting environmental protection value and economic benefits.