Isolation and characterization of novel bacterial strains for integrated solar-bioelectrokinetic of soil contaminated with heavy petroleum hydrocarbons.

This study investigated the isolation and characterization of three novel bacterial strains; Acinetobacter calcoaceticus, Sphingobacterium multivorum, and Sinorhizobium, isolated form agriculture land. From three hundred strains of bacteria, the three isolates were identified for their superior diesel degradation ability by a series of bench-scale tests. The isolates were further investigated in bench tests for their ability to grow in different diesel fuel concentrations, temperature and pH; degrade diesel fuel in vitro; and for the identification of functional genes. Semi-pilot bioelectrokinetic tests were conducted in three electrokinetic cells. An innovative electrode configuration was adopted to stabilize the soil pH and water content during the test. The genes expressed in the diesel degradation process including Lipases enzymes Lip A, LipB, Alk-b2, rubA, P450, and 1698/2041 were detected in the three isolates. The results showed that the solar panel voltage output is in agreement with the trapezoid model. The temperatures in the cells were found to be 5-7 °C higher than the ambient temperature. The electrode configuration succeeded in stabilizing the soil pH and water content, preventing the development of a pH gradient, important progress for the survival of bacteria. The diesel degradation in the soil after bioelectrokinetic tests were 20-30%, compared to 10-12% in the controls. The study succeeded in developing environmentally friendly technology employing novel bacterial strains to degrade diesel fuel and utilizing solar panels to produce renewable energy for bioelectrokinetics during the winter season.

Mitigation of soil contaminated with diesel fuel using bioelectrokinetics.

This study investigated the effectiveness of bioelectrokinetics in rehabilitating a silty clayey sand contaminated with diesel fuel using three novel bacterial strains; Acinetobacter calcoaceticus, Sphingobacterium multivorum, and Sinorhizobium, isolated form agriculture land. Three electrokinetic bioremediation cells were used to conduct the tests and a novel electrode configuration technique was used to stabilize pH and water content in the soil specimen. Solar photovoltaic panels were used to generate sustainable energy for the process. The tests were carried out in outdoors for 55 days. Applied voltage, current passing through the electrokinetic cell, and the temperature of the soil specimen were recorded periodically during the test. The pH, water content, and diesel concentration were determined at the end of the tests. Over the test period, the voltage typically increased from zero before sunrise, remained relatively stabilized for about 4 h, and then started to decrease and dropped to zero by sunset. The temperatures in the cells were found to be 5-7 °C higher than the ambient temperature. The innovative electrode configuration succeeded in keeping the pH of soil to remain the same and thereby prevented the development of a pH gradient in the soil, an important development for survival of the bacteria. The diesel degradation in the soil after bioelectrokinetics were 20-30%, compared to 10-12% in the control test. The study was successful in developing environmentally friendly technology employing novel bacterial strains to degrade diesel fuel and utilizing solar panel to produce renewable energy for bioelectrokinetic during the winter season.