Influence of abiotic factors, natural attenuation, bioaugmentation and nutrient supplementation on bioremediation of petroleum crude contaminated agricultural soil

Contamination of agricultural land(s) is a major problem worldwide which is associated with activities of petroleum industry. Due to these exploration activities remedial techniques for clean-up of contaminated agricultural soil(s) has become an alarming research topic. Hydrocarbon utilizing bacterial consortium (HUBC), isolated from petroleum crude (petroleum industry waste water and soil) contaminated sites, India has been used for soil microcosm study. The aim of present study was to compare potency of five different techniques to remediate petroleum hydrocarbons contaminated agricultural soil by employing soil microcosm study. To the best of our knowledge this is the first report for comparison of five different techniques (abiotic control, natural attenuation, biostimulation, bioaugmentation and simultaneous bioaugmentation & biostimulation) for bioremediation of agricultural soil using consortium of hydrocarbon utilizers by employing soil microcosms. Concurrent application of bioaugmentation (with HUBC) and biostimulation (with nutrient amendments) in the soil microcosm resulted in 93.67 +/- 1.80% hydrocarbons degradation in 45 days of experiment and hydrocarbon utilizing bacterial count was recorded 4.11 +/- 0.11 x 10(8) CFU/g. In the bioaugmented and biostimulated soil microcosm organic carbon was reduced from 3.49 +/- 0.08% to 0.62 +/- 0.11% with simultaneous decrease of other nutrients. The consortium could survive in artificially crude oil contaminated and nutrients amended agricultural soil microcosm and could degrade petroleum hydrocarbons effectively in soil microcosm conditions. This suggests its application as a potential bioremediation agent for farmland restoration i.e. management of soil environment.