Electrokinetic transport of diesel-degrading microorganisms through soils of different textures using electric fields.

The mobilisation of diesel-degrading microorganisms in soils of three different textures (sandy, clay and silty) using electrokinetic techniques was studied. The mobilisation tests were performed using a laboratory-scale electrokinetic cell in which a synthetic soil column was inserted between the cathode and anode compartments. Microorganisms were located at the anode compartment at the beginning of each assay. A constant cell voltage was applied, and samples were taken from the cathode and anode compartments. Microbial transport through the soil strongly depended on soil particle size. Small particle sizes (silty and clay soil) travelled at low velocities (microbial transport rates of approximately 0.06 and 0.17 cm/min, respectively), while large particle sizes (sandy soil) led to high numbers of microorganisms passing through the soil column. In sandy soil, an increase in the voltage gradient did not increase the quantity of mobilised microorganisms (approximately 10(7) CFU/mL for every voltage gradient applied). For clay and silty soils, a higher voltage gradient led to a higher quantity of microorganisms mobilised to the cathodic compartment and a lower delay time for detecting the presence of microorganisms in the same compartment.