ELECTROCHEMICAL COMBINED REMEDIATION OF CHROMIUM CONTAMINATED SOIL BASED ON STRENGTHENING BY ANODE CONSUMPTION

In order to solve the problem of focusing effect in the process of electrokinetic remediation of heavy mental contaminated soil, the electrochemical combined remediation technology at the expense of iron anode was proposed. Based on the traditional electric repair method, the combined remediation technology added the electrolyte purification circulation device and it optimized the technical parameters for the reduction and precipitation of Cr (Ⅵ). The remediation effect and applicability were evaluated by comparing with the traditional electric remediation technology. The results showed that:1) The removed Cr (Ⅵ) can be reduced to Cr (Ⅲ) and precipitated under the action of Fe²⁺, and the parameters of pH, voltage gradient, current density and electrode area all affected the reaction rate. Electrode distance had no direct impact on the reaction but reflected in the power of electrolysis. 2) The best technical parameters of Cr (Ⅵ) reduction-precipitation reaction were:pH value was 5~6.5, voltage gradient was 0.8 V/cm, current density was more than 6.67 mA/cm², electrode area was 90 cm², and electrode distance was 15 cm. 3) Compared with traditional electric remediation technology, the removal rate of different soil points fluctuated in the range of 10%, and the removal rate of highest point was increased by nearly 24% (nearly 93.4%) in the electrochemical combined remediation technology. Especially, the removal rate of chromium near anode increased from 0.24% to 80.38%. 4) The electrochemical combined remediation method based on strengthening by anode consumption could not only solve effectively the focus problem, but also help to promote the overall migration of heavy metal in contaminated soil.