Optimization and characterization of crude oil contaminated soil bioremediation using bacteria isolates:Plant growth effect

This study investigated the effect of soil pH, nitrogen-phosphorus ratio, crude oil concentration and bacteria isolates (from petroleum hydrocarbon-contaminated soil) concentration on the optimization of crude oil-contaminated soil bioremediation using central composite design. The responses were total petroleum hydrocarbons (TPH) and plant growth. A 60-day pot experiment was conducted. Natural soil, crude oil-contaminated soil and bioremediated soil were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), energy dispersive X-ray (EDX), carbon-hydrogen-nitrogen (CHN) analyser and gas chromatograph-mass spectroscopy (GC–MS). Optimum predicted values were 4.69, 7.68 g/g, 250.05 mL/L and 568.35 cell/g for soil pH, nitrogen-phosphorus ratio, crude oil concentration and bacteria isolates concentration respectively. Experimental run at optimum point affirmed the accuracy of the developed models. Characterization revealed contamination of natural soil by hydrocarbons and their biodegradation via the action of active functional groups present in bacteria isolates. Conclusively, the bacteria isolates could be applied as effective scavenger for hydrocarbon biodegradation in crude oil contaminated soil