Multi-process Based On Flat-sheet Ceramic Ultrafiltration Membrane For Advanced Treatment Of Electroplating Wastewater

As electroplating wastewater is highly toxic,it has been brought a great threat to human health and the ecological environment,therefore,the treatment of electroplating wastewater has attracted much attention.As the standards for electroplating wastewater pollutant discharge increase,conventional treatment processes cannot meet the standards for electroplating wastewater discharge.It is necessary to performce advanced treatment of electroplating wastewater to ensure discharge or reuse.To solve the key problem that the concentration of organic matter in biochemical effluent of electroplating wastewater cannot be discharged or reused,this study took the biochemical effluent of the wastewater treatment plant in an electroplating industrial park in Jiangsu Province as the raw water,focusing on the treatment efficiency of organic pollutants in biochemical effluent from electroplating wastewater by the membrane filtration,enhanced coagulation,advanced oxidation and high-efficiency adsorption treatment process,and further exploring the treatment efficiency of organic pollutants by the several different combined processes.And based on the above research results,this article developed a ceramic membrane coupling process for advanced treatment of electroplating wastewater,which is new and efficient.The analysis of the quality of the electroplating wastewater biochemical effluent showed that the biochemical effluent mainly contained organic pollutants such as humic acids,amines,amino acids,alcohols,etc.On this basis,the treatment efficiency of electroplating wastewater biochemical effluent by the ceramic membrane filtration,enhanced coagulation,advanced oxidation,and high-efficiency adsorption was investigated.The results illustrated that:?1?the ceramic membrane filtration had a better removal effect on turbidity,and the turbidity of effluent was stable below 0.5 NTU;?2?the coagulation efficiency could be strengthen with increasing the dosage of polyferric sulfate?PFS?.When the PFS concentration was 80 mg/L,the removal of TOC reached 30.46%;?3?When the ozone dosage was 50mg/L,the removal of TOC was about 46.5%,but only 15%fluorescent substances was degraded.In the presence of the 1.5 mmol/L Fe²⁺and H₂O₂,the removal efficiency of COD and TOC by Fenton oxidation under pH 4 were 31.30%and 45.68%,respectively;?4?Among activated carbon,fly ash and zeolite,activated carbon adsorption has the best removal effect on organic matter.The removal efficiency of COD and TOC reached about 80%by activated carbon adsorption in the presence of 2.0 g/L activated carbon.The removal efficiency of COD and TOC increased to 85%and 85.25%via combination Fenton oxidation with activated carbon adsorption,and the concentration of COD and TOC in effluent were below 15 mg/L and 5 mg/L,respectively.Moreover,the optimal dosage of activated carbon siginificantly decreased after Fenton oxidation.Based on the preliminary experimental results,a coupling process of Fenton oxidation-activated carbon adsorption-ceramic membrane filtration was constructed,and the operating parameters of the coupling process were optimized.In the presence of 1.5 mmol/L Fe²⁺,1.5 mmol/L H₂O₂,40 g/L activated carbon,70 L/?m²·h?critical flux of the ceramic membrane,and 2 h total hydraulic retention time of the reactor,the results of continuous operation for 30 d showed that the removal efficiency of COD and TOC were stable at about80%,the removal efficiency of turbidity was above 96%,the concentration of COD and TOC in the effluent after treatment were less than 15 mg/L and 5 mg/L,respectively,and the effluent turbidity was far less than 0.1 NTU by the ceramic membrane coupling process.The ceramic membrane coupling process could run stably,and the treated effluent could reach the designed effluent quality.After physical cleaning of the polluted membrane,the recovery rate of the membrane clear water flux could get about 85%;and further hydrochloric acid/?sodium hypochlorite+surfactant?step-by-step enhanced chemical cleaning,the recovery rate of the membrane clear water flux up to 105%,and the membrane clear water flux of the polluted ceramic membrane exceeds that of the original membrane,which was likely to be caused by the hydrophilic modification of the ceramic membrane interface and the channel wall under the action of the agents.In summary,in the new Fenton oxidation-activated carbon adsorption-ceramic membrane filtration coupling process,Fenton oxidation and activated carbon adsorption can effectively remove organic pollutants in electroplating wastewater,at the same time,and can slow down membrane fouling rate and extend the membrane operation cycle;and the ceramic membrane can further ensure that the turbidity of the effluent reach the standards.