The Treatment Mechanism Of Anode Chamber Enhanced EDI Process In Saline Heavy Metals Wastewater

There are usually contains a large amount of soluble salts in the actual industrial heavy metal wastewater.When the salt content reaches a certain concentration,the salt effect will significantly increase the difficulty of removing heavy metal ions.How to deal with Salt-containing heavy metal wastewater with high efficiency,stability,green and low consumption is not only a research hotspot in this field at home and abroad,but also a guarantee for the development of surface water ecological environment and social health.Among them,industrial wastewater with high salt content and low concentration of heavy metal ions,salt has a significant impact on various treatment technologies,and it is difficult to achievethe the goal of high efficiency,low consumption and heavy metal enrichment.In this paper,an anode chamber enhanced electrodeionization?EDI?process was proposed based on the characteristics of low-concentration heavy metal wastewater.Strong acid cation exchange resin with high ion exchange capacity was filled in the anode chamber,which can selectively remove low-concentration heavy metal ions and electrically regenerated online.Titanium mesh-based doped tin-antimony metal oxide?Ti/SbO₂-SnO₂?as the electrodes and the ionic liquid was filled in the cathode chamber,witch improves the electrical efficiency,reduces the number of ion exchange membranes.Through the research and optimization of the operation mechanism of the process,the following main results are obtained:The selection of a suitable ion exchange resin is the key to the selective removal of low concentrations of metal ions,as well as the degree of regeneration and effluent stability of the resin.The type of D001 macroporous strong acid cation exchange resin is less affected by salt concentration.When Na₂SO₄ content is 8g/L,Ni(?40??40??8?decreases from 15 mg/L to 0.66 mg/L,and the treatment effect after regeneration is stable,still reaching 99.5%.Saline heavy metals wastewater was driven into the anode chamber,which is mainly removed by cation exchange mechanism.Some heavy metal ions are enriched in the chamber driven by migration.The enrichment effect is positively correlated with the applied DC current value.In the cathode chamber,energy consumption can be reduced 28.6%by filling the ionic liquid compared with the aqueous solution of Na₂SO₄?0.1 mol/L?.For simulated wastewater with a molar ratio of co-existing salt anions to heavy metal ions of less than 56:1,the removal rate of heavy metal ions by the device can reach above 99.3%.Optimize operation and regeneration conditions for a single-stage process.Using 2.0 mA as running current,the removal rate of Ni(?40??40??8?in effluent is 100%and the effluent is stable.In order to avoid the ion exchange membrane penetration under high current,the regenerative current does not exceed 800 mA.In order to reduce the loss of long-term regenerated resin,reduce energy consumption and improve efficiency,shallow and deep alternating regenerated resin was adopted.The single-stage EDI unit was used to treat the simulated wastewater containing Na₂SO₄?1,2,3 g/L?and the concentration of metal ions?nickel,copper,cadmium and cobalt,respectively?is 15 mg/L,the effluent water quality is stable and the removal rate of metal ions is more than 99%.The device is stable after regenerated energy consumption is0.473-0.763 kWh/m³.The single-stage and multi-stage series were used to treat the actual electroplating wastewater containing 5 g/L of TDS and 389.4 mg/L Ni(?40??40??8?.3 L actual electroplating wastewater was processed by the single-stage EDI unit.Shallow regenerated resin per 200mL influent of wastewater,deeply regenerate resin for every 1L influent of wastewater,the average concentration of Ni??40??40??in effluent was 51.77 mg/L,and the average removal rate was86.71%.1.56 times Ni?II?can be concentrated by the concentrated chamber,and the regeneration is frequent,and the power consumption is 27.36 kWh/m³.3 L actual electroplating wastewater was processed by Single-stage EDI device in series with multi-level EDI device,regenerated the single-stage EDI unit after every 600 mL of wastewater treated,The average effluent nickel ion concentration is 0.053 mg/L,and the removal rate is nearly 100%,energy consumption is 8.4 kWh/m³.Resins were regenerated by electrical,recycling use of regenerating liquid and the concentrated liquid to enrich heavy metals without secondary pollution,which provide new ideas and data support for the efficient and low-cost treatment of salt containing heavy metal industrial wastewater.