Study On High-Temperature Evaporation Experiment And Integration Device Of Landfill Leachate Based On Emission Reduction Of VOCs

This paper presents a process and device for evaporating landfill leachate membrane concentrates using high-temperature flue gas,which can effectively solve the secondary pollution problem of VOCs emissions from the tail gas of evaporation devices while directly utilizing high-temperature flue gas to efficiently evaporate water.This paper focuses on the volatile characteristics of organic pollutants in the evaporation process of high temperature smoke from membrane concentrates.The experimental raw material membrane filtration concentrate was used as the membrane concentrate of a garbage disposal plant in Changsha City.A total of 63 major organic pollutants were detected,of which 39 were more than 60%reliable.Evaporation temperature of 80 ℃,100℃,120℃ and different evaporation conditions of 1h,2h,and 3h were designed.The results show that in the evaporation temperature range from 80 ℃ to 120 ℃ the evaporation process membrane concentrate concentrates with increasing temperature.The types of organic volatiles discharged are increased,and the amount of volatiles increases dramatically.There are some differences in the composition and volatilization.Significant organic species in the tail gas will also increase slightly with the extension of processing time.The types of volatile organic compounds produced will be roughly the same.Only a small amount of other substances will be detected.However,the time when VOCs release tends to stabilize will vary with temperature.Increase and lengthen.Based on the above experimental results,a combined model of high-temperature flue gas evaporative leachate concentrate with heat exchange and direct heat exchange of the first wall was designed and an experimental device was designed.The main control factors(depth of immersion)in the high-temperature flue gas evaporation process were studied.The temperature of the flue gas affects the evaporation process of the unit.The steady evaporation temperature of liquid phase is about 85 ℃,and the temperature of tail gas is above and below 90 ℃,which realizes the effect of vacuum evaporation under atmospheric pressure.This kind of state is conducive to controlling the types and release of VOCs.The difference between each change is about 3 ℃ to 6 ℃,and the temperature difference between the two is only 5 ℃～6 ℃.The small temperature difference between the gas-liquid equilibrium shows that the heat and mass transfer are adequate,the heat energy of the flue gas has been efficiently used,and a low-temperature and high-efficiency evaporation target has been achieved.The differences in the volatilization characteristics of VOCs during the evaporation process between the pilot plant and the pilot plant were compared and analyzed.As a result,it was found that the operation of the pilot plant at a low temperature resulted in the release of a large amount of low-boiling volatile components,while the high-boiling polyalkane organic matter did not appear;and there was a significant difference in the VOCs volatilization between the two,during the evaporation of a small test experiment,There is a significant increase in the volatile content of VOCs released from the evaporation of concentrated liquids.However,in the pilot plant experiments,the VOCs volatilization at different flue gas temperatures does not change significantly.At the same time,the relative contents of various components in the small-scale experiment vary greatly with the temperature of the flue gas,but the trial production equipment is not obvious,and the relative content of the volatile components tends to be stable.It shows that the designed trial equipment can achieve the purpose of emission reduction control of VOCs.Finally,a pilot study was conducted at a landfill site to treat landfill leachate using a combined DTRO+ high-temperature flue gas evaporation process.The average effluent quality of condensed effluent was COD = 45 mg/L,TDS = 21 mg/L,and TN = 6 mg/L.The salinity is 0 and the treatment satisfies the criteria in Table 2 of the "Standard for Pollution Control of Municipal Solid Waste Landfills"(GB 16889-2008).After studying the evaporation process of the membrane filtration concentrate,the components of the organic pollutants and their dynamic changes in the different processing units after evaporation,condensation treatment,and adsorption treatment were studied.It shows that the exhaust gas discharged through the device of this paper can meet the harmless emission standards,and the entire device meets the requirements for the treatment of volatile organic pollutants.