Optimization of Bioremediation Enhancement Factors in an Aged Crude Oil Polluted Soil.

Abstract

Bioremediation as an environmentally friendly method of restoration of crude oil polluted soil is influenced by several conditions. This study was designed to optimize some bioremediation enhancement factors including soil moisture content, agitation or mixing and nutrient ratio. Baseline properties of the soil samples were determined using standard analytical procedures. The crude oil polluted soil studied was seeded with mixed microbial consortium and differentially supplemented with inorganic nitrogen and phosphorus using carbon, nitrogen and phosphorus ratios 100:10:1 and 100:2:0.2. The initial sample moisture content was adjusted to 80% of its water holding capacity. Subsequently, moisture content adjustment and mixing were done at different intervals while the experiment lasted. Residual total petroleum hydrocarbon was measured every 6 days. Mixing the set-up every three days and moisture content adjustment every six days resulted in more efficient crude oil attenuation in the contaminated soil while carbon, nitrogen and phosphorus ratio 100:2:0.2 yielded statistically significant (p<0.05) higher crude oil degradation (90.99 ± 0.02%) over 100:10:1 ratio (78.15 ± 0.03%) after 36 days of remediation. The results obtained suggest that use of optimized site-specific conditions would enhance the microbial driven process of soil attenuation.