The Coupling System Of Electrocoagulation And Electric Field Enhanced Conductive Carbon Membrane Process For The Treatment Of Heavy Metal Wastewater

As the situation of heavy metal pollution continues to intensify,emission standards become more stringent,and it is difficult to meet emission requirements with a single treatment technology.In this experiment,electro-flocculation/electric field enhanced conductive carbon membrane retention system was used to treat heavy metal wastewater.Electro-flocculation as a pretreatment unit can effectively reduce the concentration of heavy metals,and then deep treatment by the electric field enhanced carbon membrane technology to achieve standard discharge.The research contents are as follows:Firstly,the optimal conditions for the treatment of heavy metal wastewater by electroflocculation system were investigated.The effects of plate material,current density,plate spacing and initial pH on the removal efficiency were studied.The results show that the electrode combination method of Fe anode-Al cathode has the best effect on the removal rate of Pb2+ and Cd2+when the initial concentration of 100 mg/L Pb2+and Cd2+heavy metal wastewater is treated.The best current density and plate for the experiment.The spacing and initial pH were 75 A/m2,1.5 cm and pH=7,respectively.Under these conditions,the removal rates of Pb2+and Cd2+ were 98%and 96.2%,respectively.Secondly,the carbon membrane was used as the anode to construct the ion trapping system,and the effects of initial solution concentration,electric field strength and initial pH on the permeation flux and removal effect of the membrane were investigated.The experimental results show that the removal rate of heavy metals decreases with the increase of initial concentration.When the influence of electric field on the membrane system is explored,it is found that the permeation flux of membrane system is due to the existence of electrophoresis,electroosmotic effect and electrochemical reaction.The removal rate of heavy metal ions was significantly improved,and the optimum field strength was 0.4 V/cm.Under the alkaline conditions of pH=7-8,the removal rates of Pb2+and Cd2+were 100%and 99%,respectively.Under the optimal conditions,the coupling system is used to treat the mixed waste liquid containing Pb2+,Cd2+,Pb2+ and Cd2+respectively,and the removal rate is 100%,which indicates that lead and cadmium are the first type of pollutants,and the maximum emission is allowed to be 1.0 mg/L and 0.1 mg/L,after coupling treatment,can reach the standard discharge.By comparing the solubility product constants of lead and cadmium,ionic radius,hydrated ionic radius and standard electrode potential,the reasons for the difference in the removal effect of the two heavy metal ions by the coupled system were analyzed.The concentration of heavy metal ions was determined by atomic absorption spectrophotometer,and the removal rate was calculated.The pore structure and heavy metal content distribution of the carbon film were analyzed by microscopic scanning electron microscopy.