Efficacy Study Of Evaporation Process For Treating High-salt Wastewater Containing Volatile Organics At Low Temperature And Ambient Pressure

This paper focused on the treatment of the high-salt wastewater containing volatile organics by the single and double effect evaporating equipment at low temperature and ambient pressure.Among of that,toluene and dimethylacetamide（DMAC）were employed separately as a sample of insoluble and soluble volatile organics in the research.The typical salts were sodium chloride,sodium sulfate,and ammonium chloride,whose weight percentage was 1.5%,2.5%,3.5%separately.Under the condition such as inflow temperature of 50℃,influent quantity of 2.5L/h,the cycle wind speed of 2m/s,evaporating temperature among 50℃⁸0℃,the key influencing factors and mechanism were studied.Based on the research,the main conclusions were as followed in this paper.（1）On account of the study of the single effect evaporating system at low temperature and ambient pressure,The treatment technology of double effect was newly built to handle the high-salt wastewater containing VOCs,which had the advantages of high efficiency,energy saving,low scaling,and sustainable commercialization.（2）The toluene and DMAC were selected as the typical organics;meanwhile,the sodium chloride,sodium sulfate,and ammonium chloride were chose to feed in the wastewater.During the range of 50℃-80℃,50 groups more than 450 tests were conducted to treat the high-salt wastewater.The results showed that the positive decline of the contents of the organics in the effluent.Seldom salts was detected through the effluent,which could meet the requirement of subsequent biological treatment.（3）The high-salt wastewater containing toluene was treated by the two systems seperately,and DMAC was handled by the double effect system.The results showed that The efficiency of double system was higher 35%rather than the single ones,and COD of the effluent was scarcely increased.（4）At the same temperature,concentration of organics and salts,the effluent quantity were sorted,ammonium chloride>sodium chloride>sodium sulfate.（5）Taking sodium chloride of 1.5%、2.5%,and 3.5%as an example seperatedly,at the temperature of 50℃-80℃,the optimum pressure was controlled above 1.24×10^-2MPa、1.97×10^-2 MPa、3.06×10^-2 MPa and 4.63×10^-2MPa in the evaporating system through the analog computation.On the basis of the lab research,the results were applied in some industrial wastewater treatment device.After the unit modification,the operating results showed that the energy saving effects was raised 45%than before,and the effluent could meet the requirement of biological treatment.The practical result indicated that the research is suitable for the industrial sewage treatment,and had high value on the practical application.