The Study Of Wastewater Containing Heavy Metal Ions Treatment By Continuous Electrocoagulation Process

The discharge of industrial wastewater has caused widespread environmental pollution, especially the heavy metal ions wastewater. It is an urgent task to treat this kind of wastewater. Electrocoagulation(EC) technology is environmentally-friendly technology for treating contaminated wastewater. Most researchers only concentrated on the removal efficiency but could not get a better understanding of the removal mechanism.This paper provides new views on the foundation of equality to promote the development of electrocoagulation process. This paper focused on the removal of heavy metal ions by electrocoagulation technology.The nickel simulation wastewater was treated with continuous aluminum electrocoagulation in this paper. The influence of current intensity, residence time and initial pH on the removal of Ni(Ⅱ) was investigated. And the optimum parameters have been obtained. This paper also focused on the continuous process from the perspective of mass transfer. The results showed that there exists back mixing in continuous EC process.The back mixing at the direction of streamline was dependent on both fluid dynamics and mass transfer. A new parameter named the ratio of M/Al was proposed to quantify the utility of electro-generated Al ion.The ratio changed over current intensity, residence time and initial pH. It has a closer relationship with the removal efficiency of Ni(Ⅱ).The passivation of electrodes limit the development of EC technology. This paper investigated the mechanism of polarization and passivation. The influence of pulse frequency, duty factor, current intensity and residence time on the removal of Ni(Ⅱ) was investigated in the pulsed electrocoagulation process. The conditions of Al-Electrocoagulation have been optimized: duty factor 30%, pulse frequency 1000 Hz, current density 22.5 A /m2, the ion removal is 94.76%. On the same conditions, compared with direct current electrocoagulation, the pulsed process can save energy and relieve back mixing with the close removal.Continuous aluminum electrocoagulation was applied for the removal of Cu(Ⅱ) and Zn(Ⅱ) from wasterwater on the same conditions in this study. Several parameters such as initial pH, residence time and current intensity on the removal were studied in this paper. The results showed the impacts of electrocoagulation process on the removal of divalent metal ions and proved the feasibility of M/Al.