ABSTRACT

Environmental pollution as a result of oil spillage during extraction, processing, transportation and corrosion or damage of pipeline is one of the many disasters that have been caused by humans throughout history. The influence of incorporating different types of organic waste in bioremediation of crude polluted soils was investigated in this study. Five treatment levels of crude oil pollution (0, 20, 40, 60, and 80 ml) were used, while amendment treatments were done after two weeks. The different organic waste: Poultry manure (PM), Cow manure (CM), Poultry manure + Cow manure (PM+ CM), with two sets of control: pollution + no amendment and no pollution + no amendment were used for this investigation. Results show that the crude oil significantly affected the physicochemical properties of the soil. Two weeks after crude oil pollution a decline in pH values was observed for all crude oil polluted soil with increased amount of crude oil. Other parameters that had notable reduction in values with increased crude oil volume include Calcium, Potassium and Phosphorus while percentage total organic carbon, total organic matter and total hydrocarbon content (THC) significantly increased. The results also showed that the organic manure amendment treatments significantly decreased crude oil toxicity at different degrees by improving the nutrient content and decreasing the total hydrocarbon content of the soil. The results indicated the order of their remediation potential as PM+CM> PM > CM. The microbial composition of the PM and CM which could have contributed in the biodegradation process as identified using 16S rDNA sequencing include: Lysinibacillus sphaericus, Lysinibacillus fusiformis, Enterobacter cloacae, Bacillus amyloliquefaciens, Aspergillus niger and Enterobacter asburiae. Nucleotide sequences of the isolates retrieved from this study have been deposited in the GenBank nucleotide sequence database under accession nos. MT560691, MT500581, MT498090, MT500681 and MT500680 (NCBI GenBank, www.ncbi.nlm.nih.gov). Therefore, this study shows that the reduction of crude oil pollutant in soil using organic waste should be encourage and locally propagated for economic reasons.