Enhanced electrokinetic bioremediation by pH stabilisation

Abstract

A new technique to stabilise pH during electrokinetic bioremediation is investigated. The technique employs an anode and a cathode in the same compartment (anode−cathode compartment (ACC)) placed side by side at each end of the soil under treatment. Tests using ACC technique were performed along with control tests conducted using a conventional anode−cathode (CAC) configuration. The efficiency of ACC and CAC configurations in delivering nitrate inside soil was investigated. The results showed that, the pH values at the anode and the cathode compartments after CAC tests were around 2 and 11, respectively. For the ACC, the pH at the water compartments was between 7·2 and 7·8. The pore fluid pH at the end of the tests varied between 2·7 at the anode and 8·0 at the cathode in the CAC and remained close to the initial pH in the ACC. The nitrate concentration in CAC was high near the anode (2700 mg/l) but low in subsequent sections with lowest concentration near the cathode (105 mg/l). For the ACC, a relatively uniform nitrate concentration between 1300 mg/l and 800 mg/l was reported. The results showed that the novel ACC configuration is effective in stabilising the soil pH and distributing nutrients evenly across the soil.