电絮凝去除废水中多种重金属影响因素研究

目的以铁作为电极,研究电絮凝法处理含多种重金属废水的影响因素及效果。方法通过控制pH、停留时间、电流密度、电导率、废水初始浓度等因素至不同水平,考察处理效果、能耗及极板消耗的变化。结果随着停留时间、pH值及电流密度的升高,处理效果越好,但升高至一定程度后,处理效果提升并不明显;电导率对处理效果影响并不显著,但过低的电导率会增加能耗;废水初始浓度越高,要达到处理目标所需的能耗及极板消耗均越高。结论当pH为8.5~9.0、进水电导率为1500~2000μs/cm、停留时间为3~4 min、废水初始质量浓度20 mg/L、电流密度为13.2~19.8 A/m2时,处理效果最理想,对总铜、总镍、总铅、总锌、总镉及总铬的去除率达到99%以上,且能耗与极板消耗均为最低,电絮凝法更适合于重金属废水的深度处理。

Influencing Factors on Heavy Metals Removal by Electrocoagulation Treatment

Objective To study the influencing factors on heavy metals removal by electrocoagulation treatment. Meth-ods Wastewater was treated with electrocoagulation by using iron plate as electrode. Several affecting factors, such as reten-tion time, initial pH, current density, conductivity and initial concentration were investigated. Results The removal rate was obviously improved with the increase of retention time, initial pH and current density, however, the improvement of treatment effect did not continue after reaching a certain level. Conductivity did not influence the treatment effect, but low conductivity increased energy consumption. To achieve the desired treatment effect, the higher the initial concentration of wastewater, the higher the consumption of energy and plates. Conclusion Electrocoagulation was more suitable for advanced treatment of wastewater containing heavy metals. The removal rates of total copper, total nickel, total lead, total zinc, total cadmium and total chromium were above 99% under the conditions of initial pH of 8. 5~9. 0, conductivity of 1500~2000μs/cm, retention time of 3~4 min, current density of 13. 2~19. 8 A/m^2 and initial concentration of 0~20 mg/L.