Membrane Electrolysis Technology For Treating High-concentration Copper-containing Electroplating Wastewater

Nowadays,with the development of high-end technology industry,electroplating industry has gradually become an indispensable part of the current development stage,and the pollution problem caused by electroplating wastewater discharge still plagues us.For heavy metal pollutants in electroplating wastewater,at present,most electroplating enterprises in China continue to use the traditional chemical precipitation method.Although the cost of this method is low,the additional chemicals are easy to cause secondary pollution.Based on the wastewater quality of an electroplating enterprise in Gansu Province,a process scheme of ion enrichment technology and membrane electrolysis technology to treat and recover copper containing electroplating wastewater was designed.The purpose of enrichment and concentration is not only to provide high concentration copper containing wastewater for the follow-up membrane electrolysis process,but also to control the end effluent quality within the range of national discharge standard.Membrane electrolysis process can realize the recovery and utilization of copper and sulfuric acid,and create economic value.For the part of ion enrichment and concentration,the special device of"double columns,reverse countercurrent regeneration"is designed,and three stages of ion exchange,elution regeneration and backwashing are set.Compared with the traditional enrichment and concentration device,the device can not only ensure the water quality of the effluent at the end of the ion exchange process,but also improve the ion recovery rate by reverse elution and regeneration.In addition,two reaction columns are alternately used as the main reaction column,which saves the redundant backwashing process,which is also a major advantage of this treatment scheme.The optimal operation parameters of this process were determined in the experimental study of control variables,and the continuous operation cycle test showed that the effluent Cu²⁺concentration of ion exchange process could be controlled in 0.2?0.3mg/l,which met the requirements of emission standards;while the Cu²⁺concentration in eluent could reach 30g/L,the concentration multiple could reach 300 times,and the recovery rate could be more than 99%.In the experiment of exploring the effect of membrane electrolysis on the treatment and recovery of high concentration copper containing wastewater,three stages were designed:pre experiment,orthogonal experiment and single factor experiment.In the process of pre experiment,according to the comparison of different anode materials,titanium coated iridium ruthenium electrode with low oxygen evolution potential was selected as the anode electrode of this experiment.In addition,the optimal reaction time for a single group of experiments was determined as 5h.Then,the influence of current density,initial concentration of Cu²⁺,temperature,pH value and plate spacing on the recovery of copper and sulfuric acid was explored in the orthogonal experiment.It was found that current density and initial concentration of Cu²⁺had great influence on the experimental results.Through orthogonal experiment,the preliminary analysis values of the best experimental conditions were obtained:the initial concentration of Cu²⁺was 50g/L,the current density of cathode plate was 400A/m²,the temperature was 30?,the distance between plates was 30mm,and the pH of cathode chamber was 5.5.Finally,in the single factor experiment,the effects of various factors on copper recovery and reaction energy consumption were explored in detail.It is found that the abnormal hydrogen evolution reaction and Cu²⁺reduction reaction in the cathode chamber are the main factors affecting the copper recovery.Finally,after experimental correction,the optimal reaction temperature was adjusted to 40?,while the pH value of cathode chamber was maintained at 6?6.5.In addition,adding an appropriate amount of ammonium nitrate at the beginning of the reaction can promote the Cu²⁺reduction reaction,and the optimal amount of ammonium nitrate is 1.0g/L.Through the continuous operation test under the optimal electrolysis parameters,the copper recovery rate can reach more than 95%,the current efficiency is more than 70%,and the reaction energy consumption value is 5300?5400k W·h/t.After the end of the experiment,the cost of all the experiments in this study is calculated,and the economic value of copper and sulfuric acid recovery is estimated,and the final economic benefit prediction is fitted.It is concluded that the net income of 2.42 yuan can be generated by treating each ton of electroplating wastewater.Compared with the current wastewater treatment method of the electroplating enterprise,about 1200 yuan can be generated by treating 200 tons of copper containing wastewater every day.It can be seen that the project not only solves the secondary pollution problem of traditional heavy metal wastewater treatment process,but also realizes the sustainable development goal of resource recycling.Although the scheme is still in the laboratory research stage,there is still a lot of room for improvement in the actual project operation,but the superior performance of ion exchange resin and ion exchange membrane in water treatment,coupled with the energy cleanliness of electrolytic wastewater treatment,can ensure the feasibility of this process in the actual wastewater treatment.In the future,we need to improve the device materials,optimize the process parameters and other ways to carry out research and exploration in practical application,and strive to promote the technological innovation process of ion exchange technology and membrane electrolysis for electroplating wastewater treatment.