The Study On Membrane Separation Technology Applied In Industrial Saline Wastewater Treatment

Membrane separation technology is a new separation technology to separate andpurify the mixtures with a selective permeability membrane under the action of thechemical potential difference or external energy. Membrane separation technologyplays a very important role in various aspects of people’s lives as a highly efficientseparation technology, especially widely used in the desalination of sea water and therecycling of saline industrial wastewater. With the rapid increase and development ofthe population and the economic, shortage of water resources is becoming more andmore serious. So people pay more attention to the treatment of domestic sewage andindustrial wastewater. Membrane separation process can be divided into the reverseosmosis, electrodialysis, dialysis, microfiltration, pervaporation, ultrafiltration, gasseparation and so on. In this paper we use reverse osmosis, electrodialysis andion-exchange membrane electrolysis technology to treat different saline industrialwastewater and study the effect of these methods.（1）The titration result we measured in the propylene oxide saponificationwastewater is that the concentration of calcium ion is0.2243mol/L while theconcentration of chloride ion is0.4400mol/L. The mass fraction of sodium chloride inthe propylene oxide saponification wastewater is nearly2%after the pretreatment,and it can reach to6%by the reverse osmosis treatment for certain time. Theconductivity of the dilute water is so low that it can reach the standard of industrialwater. The desalination rate is97.81%, and the consumption of every one literwastewater is3.54×10^-2kw·h.（2）We used the concentrate of the reverse osmosis process as the starting solutionof electrodialysis. We can concentrate it from6%to20%by electrodialysis consumed2.81×10^-2kw·h one liter, which make the utilization of the wastewater a reality. We also studied the influence of different process conditions on the electrodialysis effect,such as voltage, the initial concentration and the flow rate. The size of voltage impactcurrent efficiency greatly. The current efficiency increases with the voltage firstincreases, and then decreases. It rise to65%when the voltage is30V.（3）In this part the splitting of sodium sulfate was performed in athree-compartment membrane electrohydrolysis cell, combining commercial cationand anion exchange membranes. We can get sulfuric acid and oxygen in the anode,sodium hydroxide and hydrogen at the cathode at the same time. By the orthogonalexperiment we found the experimental conditions for the highest current efficiency:current density of30mA/cm², sodium sulfate concentration of1.4mol/L, electrolysistime of1hour. Under such conditions, the anodic current efficiency is64.13%whilethe cathodic current efficiency is83.16%. We also studid the effect of the currentdensity, concentration of sodium sulfate, electrolysis time, flow rate, and the type ofion exchange membrane on the current efficiency and energy consumption.