Pilot-scale electrokinetic treatment of a Cu contaminated red soil

A pilot-scale experiment for electrokinetic treatment of 700 kg of copper contaminated red soil was conducted using a constant voltage of 80 V. Dynamic removal percentages of Cu from the soil and energy consumption during the treatment were evaluated together with changes of soil pH, electrical conductivity and soil microbial functional diversity before and after the electrokinetic treatment. The results indicate that 76% of Cu was successfully removed from the soil after 140 d of treatment when lactic acid was used as enhancing reagent for adjusting the catholyte pH and dissolving soil Cu by complexation, and the pilot-scale electrokinetic experiment consumed electric energy of 224 kW h t-1 soil. The post-treatment soil pH values decreased about 0.1-1.6 units compared with the initial value (pH 4.8), and soil electrical conductivities in most of soil sections also significantly decreased. Soil microbial functional diversity varied after the electrokinetic treatment, particularly the increase of substrate richness index, which is possibly due to the stimulation of lactic acid that was introduced into the soil column during the experiment.