Study On The Effect,Mechanism Of Iron And Manganese Removal From Acid Mine Wastewater By Electro-Fenton Process

The treatment of acid mine wastewater has been a lot topic in recent years.The high concentration of iron and manganese ions in the wastewater has caused great harm to the environment and the human body.The traditional treatment methods often have the disadvantages of low efficiency,high cost,low treatment concentration,large sludge output,and controlled environmental conditions when treating acidic iron-containing manganese wastewater.How to simultaneously and efficiently remove iron and manganese ions in acid mine wastewater had become an urgent problem to be solved.The electro-Fenton process has been widely used in the various non-degradation organic pollution in these years.Some research shows that the electro-Fenton process could achieve great effect in the treatment of heavy metal pollution.But the application of this process was rarely reported in the acid mine wastewater treatment.In this paper,the acid wastewater from an abandoned coal mine was taken as the study object,and treated by electro-Fenton process.The main conclusions of this paper were shown as follows:The cathode and anode used in the electro-Fenton treatment were compared.This study take graphite,stainless steel,Ti mesh,Ru O₂/Ti mesh,active carbon fiber felt,nickel foam as research objects.The treatment effect,stability,and cost of Fe²⁺and Mn²⁺treatment were compared.The result show that when Ru O₂/Ti mesh was used as anode,and active carbon fiber was used as the cathode,the removal efficiency of Fe²⁺and Mn²⁺could achieve highest effect,and it has higher stability and lower treatment cost.The treatment effect on Fe²⁺and Mn²⁺ by electro-Fenton process were investigated under the conditons of static of acid mine wastewater.Results show that the removal efficiency of Fe²⁺and Mn²⁺in wastewater reached 99.2%and 90.5%,respectively,under the optimal conditions(current intensity 200 m A,initial pH 4,plate spacing 1.5 cm,aeration rate 80 ml/min).Through the study of different coexisting ions,it was found that sulfate can improve the treatment efficiency of the electro-Fenton process.However,the presence of carbonate and phosphate has an inhibitory effect on removal of Fe²⁺and Mn²⁺in the electro-Fenton system.In the electro-Fenton system,the hydroxyl radical(·OH)played an important role in remove of Fe²⁺and Mn²⁺.Fe²⁺and Mn²⁺were oxidized by·OH to high valence state,then Fe(OH)₃ and Mn O₂ was generated and separated from the solution to completed the purification of wastewater.This inference also was confirmed by SEM?EDS?XPS?XRD.The treatment effect on Fe²⁺and Mn²⁺ by electro-Fenton process were investigated under the conditons of simulating the flow of acid mine wastewater.Results show that the removal efficiency of Fe²⁺and Mn²⁺in wastewater reached 97.5%and 88%,respectively,under the optimal conditions(current intensity 250 m A,initial pH 3.5,plate spacing 2 cm,flow rate 40 ml/min,and aeration rate50 ml/min).The electro-Fenton process still had a good treatment effect in the treatment of acid mine wastewater under flow conditions.The electro-Fenton process could achieved good effect in actual wastewater treatment,the removal efficiency of Fe²⁺and Mn²⁺was 95%and 87.5%,respectively.The decrease in removal efficiency may be caused by the interference of coexisting ions.Under the condition of continuous operation,the removal efficiency of the electro-Fenton process did not change significantly,which showed that the electro-Fenton process has higher stability when treating acid mine wastewater.The economic advantage of electro-Fenton process was compared with limetstone process and electrocoagulation process,it could be concluded that the electro-Fenton process could greatly reduced the cost of acid mine wastewater treatment.It could be seen from this research that the electro-Fenton process could achieve great results in acid mine wastewater treatment.Acid mine wastewater provided low pH condition and Fe²⁺as a Fenton catalyst.Fe²⁺and Mn²⁺in wastewater were simultaneously and efficiently removed.The additional cost of chemicals was reduced,and the secondary pollution was smaller.The above results could provide references for the efficient treatment acid mine wastewater containing Fe²⁺ and Mn²⁺ by the electro-Fenton process.