Simultaneous removal of Fe(II) and Mn(II) from acid mine wastewater by electro-Fenton process

•Fe(II) and Mn(II) in acid mine wastewater was efficiently removed by electro-Fenton process.•Reaction mechanism and mutual promotion effect in the electro-Fenton system was investigated.•No electro-Fenton process has been studied to treat Fe(II), Mn(II) acid mine wastewater before.•The economic advantages of electro-Fenton process were evaluated.•Response surface method was used to optimize conditions. The treatment of acid mine wastewater containing Fe(II) and Mn(II) has been a hot topic in a long time. This paper studied the treatment of acid mine wastewater by the electro-Fenton process. First, the effect of key parameters including initial current intensity (50−300 mA), plate spacing (0.5–3.0 cm), and initial pH (3.0–5.0), aeration rate (0−200 mL/min) were studied. Based on these results, the performance of electro-Fenton process in actual wastewater and the stability of electro-Fenton system were investigated. Then the removal mechanism and mutual promotion effect were analyzed. The removal efficiency of Fe(II) and Mn(II) in wastewater could reach 99.2 % and 90.5 %, respectively, under the optimal conditions (current intensity 200 mA, initial pH 4.0, plate spacing 1.5 cm, aeration rate 100 mL/min). Electro-Fenton process has an important effect in actual wastewater treatment (removal efficiency of Fe(II) and Mn(II) reached 96.5 %, and 87.5 %, respectively), while the stability of this process was good. The optimal conditions were optimized through Box-Behnken design and response surface method (RSM). Removal efficiency of Fe(II) and Mn(II) could reach 99.6 % and 92.9 %, respectively, under optimized conditions (current intensity 210 mA, plate spacing 1.6 cm, initial pH 4.0, aeration rate 110.4 mL/min). In addition, the economic advantage of electro-Fenton process in acid mine wastewater treatment were evaluated. The result indicated that the cost of electro-Fenton process was only 0.56 $/m3.