Electrobioremediation as a hybrid technology to treat soil contaminated with total petroleum hydrocarbons

Contaminated soil with Total Petroleum Hydrocarbons (TPH) was subjected to treatment in an experimental prototype with effuent recirculation. A 2^k experimental design was used, with two factors (electric field and microorganisms' growth) and two levels (presence and absence of the factors), resulting in 4 treatments (triplicate) designated as: leaching, bioremediation, electroremediation, and electrobioremediation. Total petroleum hydrocarbons attached to the soil surface showed a higher migration to the aqueous phase due to the application of low intensity current. Growth of native microorganisms present in the soil was stimulated with the addition of micro and macronutrients; TPH were degraded used as carbon source and electron donor, using oxygen (aeration) as electron acceptor. There were statistical significant di_erences between treatments supporting EBR as the best alternative. Results showed 24.5 ±3.1% of TPH removal from the soil into the aqueous phase for lixiviation and 32.1 ±1.4% for bioremediation, both at 360 hours. For electroremediation a 54.8 ±2.2% removal (360 h) and 68% (700 h) and 68.6 ± 3.8% (360 h) and 89% (700 h) for electrobioremediation. Remediated soil in electrobioremediation reached 2,596 mg TPH/kg soil, such concentration is lower than the maximum permissible limit (MPL) set by Mexican regulation.