Title : Biostimulation and bioaugmentation in the presence of plant rhizosphere for the petroleum polluted soil treatment
Abstract:
Present study demonstrates the systematic strategies of bioremediation in the highly crude oil contaminated soil of Shengli oil field near Yellow River Delta China. Breakdown of the crude oil contaminant by soil microbial community in the bioremediation was enhanced due to the presence of plant rhizosphere, but plant cannot grow and tolerate the high concentration of hydrocarbon. Composting was done in the first step with maize straw and pine wood chips, soybean cake and NH4HCO3 which decreased the TPH concentration from 17,900 mg kg-1 to 3700 mg kg-1. For further treatment, in order to enhance the degradation, bioaugmentation with free and immobilized bacterial culture was done in the composted soil on lab scale, immobilized culture showed insignificantly better degradation 39.68% than free bacterial culture 31.64%. In the last step, bioaugmentation was done in combination with Sesbania cannabina growth in which control plant without bioaugmentation has showed best result and decreased the concentration of previously composted soil to 520 mg kg-1 (75% net removal rate). It explored the facts that plant rhizosphere selected microbial community, which was more suitable for pollutants degradation than bioaugmented bacterial culture. Rhizodegradation followed by composting has found to be a promising technique for the remediating highly contaminated soil, while bioaugmentation with immobilized and free bacterial cultures has shown to be more effective in the absence of plants.
