Study On The Desalination Effect Of Wastewater Based On Deionization Process With Liquid Filled Electrode

The high salt content in the wastewater not only poses a threat to the water ecological balance,but also affects the removal effect of other pollutants by the conventional treatment process.Its sources mainly include industrial wastewater,brackish water and non-flowing sodium wastewater.Among them,industrial wastewater of heavy metals usually contains certain salinity.After the treatment of lead-acid battery wastewater by neutralization and precipitation process,its heavy metal ion concentration is relatively low,but the higher inorganic salt content produces the salt association effect,which makes it difficult to remove trace heavy metal ions efficiently.In order to achieve the goal of efficient desalination,the paper adopts the self-made Liquid-filled electrode CDI device with low consumption,high efficiency and easy regeneration to treat 70 g/L simulated saline wastewater,and designs the flow electrode FCDI device on the basis of Liquid-filled electrode CDI device to conduct desalination experiment.The main research results are as follows:NaOH was used as the precipitates for the pretreatment of lead-acid battery wastewater?pH=9?.The Pb²⁺concentration after one sedimentation decreased from 3.67 mg/L to 0.3⁰.4 mg/L,and the salt content decreased from 7.39 g/L to 3.24 g/L.The main component was Na₂SO₄.In order to further reduce the salt concentration,a capacitive deionizing?CDI?device with Ti/CAC was used for desalination.After 21 cycles,the salinity of water after one sedimentation decreased to 0.03 g/L,and the desalination rate reached 99.07%,but the electrode regeneration was difficult.In order to improve the regeneration effect of Ti/CAC electrode,avoid the ion effect during the regeneration process and solve the problem of contact resistance,a preliminary study was carried out on the carbon fiber advanced membrane capacitor electrode.To solve the problem of difficult regeneration of Ti/CAC electrode,a liquid-filled electrode CDI device was designed.A homogeneous ion exchange membrane was set between the anode and cathode Chambers and the desalination chamber.After the optimization of desalination conditions,when the concentration of CAC electrode solution was 1000 mg/L,the flow rate was 5 mL/min,the constant current was 30 mA,and the desalination cycle was completed for 18 times,the salinity of simulated high-salinity wastewater KCl?70g/L?was successfully reduced to 8.91g/L,which improved the desalination efficiency.However,Ti/CAC electrode still needed to be regenerated.In order to facilitate the replacement of electrode fluid by liquid-filled electrode CDI device,the flow electrode capacitor deionization?FCDI?process was designed and optimized.When the flow rate ratio of electrode solution to brine was 20:10,the current was 5mA,and the combination of the flowing electrode slurry was 6%CAC+1%carbon black+2mL dispersant DMF,the salinity of the simulated high-salinity wastewater?KCl 70 g/L?could be successfully reduced to 9.9 g/L after 15 groups of circulation.The flow electrode FCDI device can achieve continuous desalination by replacing the electrode fluid.Since the removed salt ions are mainly absorbed on the CAC in the electrode fluid,the CAC can be separated for enhanced regeneration,thus reducing the cost of FCDI desalination.FCDI process provides a new option for desalination of high salinity wastewater.