bioremediation of diesel fuel contaminated soil using cow manure

so far, different methods have been applied to clean up soils contaminated with oil. bioremediation is one of the clean up technologies which uses microorganisms or microbial processes to degrade oil contaminations in soils. this study evaluates the applicability of cow manure as bioremediation alternative for soils spiked with petroleum hydrocarbons. target contaminant of this research was diesel fuel which was spiked at 60000 mg/kg sample on a dry weight basis. the major goal of this research was to find the appropriate mix ratio of cow manure for enhancing diesel fuel degradation during contaminated soil composting. the ratios of contaminated soil to cow manure were 1:0.15, 1:0.3, 1:0.5 and 1:1 as wet weight basis in 3 replicates. to examine the circumstances conditions on degradation process, we determined the c/n, c/p and total bacterial count (tbc) of treatments at start, week 5 and week 11(end of study). total petroleum hydrocarbons (tph) were measured by usepa standard method 8015b using gc-fid. the degradation of diesel fuel was significantly enhanced by the addition of cow manure as compared to the control treatment and tph degradation results were better described using a second- order kinetic model. the experimental data indicated that the most degradation rates occurred in the first 5 weeks. by week 5, 50% of the original tph was removed in the 1:1 treatment. after this period, degradation trend of diesel fuel showed a lower removal rate. at the end of study, the most active degradation of tph was observed at the soil to cow manure mix ratio of 1:1 with 62% removal whereas the 1:0.5 treatment degraded 58% of tph contamination. no statistically significant difference was observed between 1:1 and 1:0.5 treatments (p<0.05). statistical analysis showed high correlations among the amount of tph degraded and tbcs(r = 0.733).