Study On Eutectic Freezing Crystallization Method For Treatment Of Industrial High-salt Organic Wastewater

The eutectic freeze crystallization method is a new water treatment technology for realizing wastewater purification and pollutant concentration by the principle of solid-liquid phase equilibrium in physical chemistry when the temperature is below the eutectic point.The treatment of wastewater by eutectic freezing crystallization has the advantages of wide applicability,low corrosiveness to equipment,low energy consumption,and the ability to recover useful materials in wastewater.In this paper,eutectic freezing crystallization method was used to study industrial high-salt organic wastewater.The recovery of sulfuric acid from inorganic crystalline salt and chemical fiber wastewater was successfully recovered from wastewater.The quality of ice crystals recovered in different volume concentration fractions and sulfuric acid in concentrated liquid were investigated.The law of variation explores the feasibility of recycling inorganic salts in wastewater.Three single system solutions of different concentrations of sodium sulfate,copper sulfate and potassium sulfate were treated by eutectic freezing crystallization method.The solution temperature and sulfate concentration under eutectic point were determined by low temperature cooling curve method.When the concentration multiple was ten times,to investigate the recovery rate of three sulfates and the proportion of salt in ice-thaw water.The experimental results show that the eutectic point temperatures of the three single system solutions of sodium sulfate,copper sulfate and potassium sulfate are:-1.23℃,-1.55℃ and-1.53℃,respectively,eutectic concentration: 3.80%,11.83%,6.62%;When the concentration multiple reaches ten times,the recovery rate of the three salts can reach more than 70%.For the system with the sulfate concentration greater than the eutectic concentration,the recovery rate of the sulfate can reach more than 85%.The eutectic freezing crystallization method was used to treat the acidic wastewater generated during the chemical fiber production process.The temperature of the eutectic point of the wastewater and the concentration of sodium sulphate were determined.The changes of freezing point under different volume concentrating times and the sodium sulfate,sulfuric acid and COD in the wastewater were investigated.The law of change in p H and conductivity.The experimental results show that when the concentration of the body reaches ten times,the concentration of sulfuric acid in ice-melted water is 1.75 g·L^-1,and the removal rate is89.72%;the concentration of sulfuric acid in the concentrated solution reaches 172.99 g·L^-1,and the recovery rate of sulfuric acid Up to 87.20%.The concentration of sodium sulfate in ice-melted water is 3.56 g·L^-1,the removal rate is 94.07%;the recovery of anhydrous sodium sulfate is 37.71 g,and the recovery rate is 78.50%,which can meet the standard of enterprise wastewater resource.