A Comparative Study on the use of Soil - Organic and Inorganic Biostimulants in the Remediation of Oily Waste

Remediation of oily waste using soil-organic (goat dung, poultry dropping) and inorganic (NPK fertilizer) nutrients was assessed for twelve weeks using culture-dependent microbiological technique and chemical procedures. The results indicate increased counts of Hydrocarbon-utilizing bacteria, fungi and actinomycetes with remediation time for both nutrient types. Bacteria in the remediated waste were members of the genera Bacillus, Pseudomonas, Acinetobacter, Alcaligenes and Serratia, fungi: Penicillium, Aspergillus and Cladosporium, and actinomycetes: Rhodococcus, Nocardia and Streptomyces for all soil-nutrient amendment techniques. pH of the NPK fertilizer ranged between 6.7 ± 0.03 and 7.3±0.06 whereas the goat dung and poultry dropping amendments was 6.5± 0.02 and 7.1 ±0.05. Dehydrogenase activity increased for the biostimulant treatment cells with remediation time. Total Petroleum Hydrocarbon reduction was 99.3 and 99.6% in organic and 99.8% for inorganic amendments. Polycyclic Aromatic Hydrocarbons of the remediated waste for both techniques revealed values below detectable limits (< 0.01) at the end of remediation period. Remediation with soil-goat dung and soil-poultry dropping amendments compared favorably with soil-NPK fertilizer technique because microbial activities were enhanced to produce eco-friendly waste. The use of soil-organic amendments is therefore a low-cost alternative biostimulant for the management of oily waste in the petroleum industry.