Study On Diffusion Dialysis-Electrodialysis Treatment And Acid Recovery Of Nitrocellulose Production Wastewater

In this paper,the acid wastewater produced by the production of nitrocellulose in a chemical plant in Henan Province is taken as the research object,and the acid wastewater is treated by the combination process of“diffusion dialysis-electrodialysis”to achieve the purpose of resource utilization.Acid wastewater mainly contains nitric acid,sulfuric acid and organic matter,the acidity is 9-10g/L,the main pollutant COD concentration is 180-280mg/L,BOD₅70-105mg/L.According to the needs of enterprises,refer to the chlor-alkali industry recovery sulfuric acid standard?HG/T 5026-2016?,the purpose of this paper is to make the treated acid wastewater COD<50mg/L,acidity>25g/L,the acid is recycled.Combining the existing theoretical basis and related literature,the effects of various factors on COD removal and acid recovery are explored through experiments,and the optimal parameters of each process are determined to provide technical support for engineering design and application.The diffusion dialysis test determines the flow ratio of the feed liquid,the flow rate of the feed liquid to the deionized water,the acidity and temperature of the feed liquid,and the related process parameters.The acid-water flow ratio is 1,the flow rate is 1.0m/h,the temperature is 30?,and the acidity of the wastewater at 9.5 g/L,the acid recovery is 94.16%,the COD rejection is 84.81%,the acidity is 7.7 g/L,and the COD concentration is 43.5 mg/L.The electrodialysis test determines the relevant process parameters such as membrane type,flow rate,current density,voltage and time,and selects the homogeneous membrane for electrodialysis test.The flow rate is 30L/h and the current density is 6.67A/m².When the test is carried out for 40min,the acid recovery rate is98.75%,the acidity is 28.5g/L,the current efficiency is 82.24%,and the power consumption is 2.6KWh/molH⁺.The separation of NO₃^-and SO₄^2-by monovalent selective anion membrane electrodialysis was discussed,and the relevant process parameters such as flow,current density,voltage and time were determined.When the voltage was constant,NO₃^-and SO₄^2-were relatively low when the current was constant.At the flow rate of 10 L/h and the current density of 6.67 A/m²,the separation efficiency of NO₃^-and SO₄^2-is about37.77%in the experiment for 30-60 min.At this time,the NO₃^-concentration multiple is4.04,and the SO₄^2-concentration multiple is 2.89.When the diffusion dialysis machine and the electrodialyzer produce membrane fouling,the diffusion dialysis machine adopts 1%NaOH solution for membrane cleaning.After 120 minutes of washing,the membrane flux recovery rate is 82%;the electrodialyzer uses the deionized water with the flow rate of 30 L/h to hydraulically rinse the membrane.After 60 minutes of washing,the membrane flux recovery rate is87.46%.