Use of Hydraulic Pressure–Improved Electrokinetic Technique to Enhance the Efficiencies of the Remediation of PCP-Contaminated Soil

This investigation examines use of the electrokinetic (EK) technique in the remediation of low-permeability soil that is contaminated with pentachlorophenol (PCP). The EK system, which includes an electrolyte injection system, improves the efficiency of removal and the degradation of PCP, and performs dechlorination. Experimental results reveal that the species of electrolyte influences the generation of the electric current, the pH of the electrolyte, the pH of the soil, and the rate of electroosmotic flow (EOF). The latter influences the efficiency of remediation of the contaminated soil. Following 72 h of treatment, the overall PCP removal rates that were achieved using NaOH, tap water, and ${\mathrm{Na}}_2{\mathrm{SO}}_4$ electrolytes were 81.74, 11.47, and 29.81%, respectively. In this study, the obtained electroosmosis permeability ($K_{eo}$) values, ranging from $4.52\times {10}^{-5}$ to $6.17\times {10}^{-5}{\mathrm{cm}}^2/\mathrm{Vs}$, were considerably higher than the values of typical hydraulically induced flow in soil. After 48 (T2) and 72 (T3) h of treatment with NaOH as the electrolyte, the total energy consumption was 492 and $582\mathrm{kWh}/{\mathrm{m}}^3\text{-}\mathrm{soil}$, respectively. The energy consumption per unit mass of PCP removed revealed that T3 ($14\mathrm{kWh}/\mathrm{g}\text{-}\mathrm{PCP}$) was associated with a more efficient use of energy and the results for T2, T4, and T5 indicate that using NaOH as the electrolyte improved the removal efficiency, saved energy, and reduced the processing time. An evaluation of cost-effectiveness indicates that an EK system that included an electrolyte injection system and used NaOH as the electrolyte provided a favorable removal efficiency and rate of degradation of PCP.