Biodegradation of Crude Oil Polluted Soil by Co-Composting with Agricultural Wastes and Inorganic Fertilizer

Abstract

Pollution of the environment by petroleum products is inevitable due to oil production,   transportation and distribution activities.   The present study is aimed at examining the extent of bioremediation that can be achieved in crude oil polluted soil after supplementing with organic manure (poultry droppings and goat dung); inorganic fertilizer (NPK 15:15:15) and saw dust respectively.

A bioremediation study was carried out on soil experimentally polluted with Bonny Light crude oil by supplementation with organic and inorganic nutrients (poultry manure, goat dung, saw dust and NPK fertilizer). The efficacy of the treatments was monitored for 112days by the measurement of total hydrocarbon utilizing bacteria load and some physico-chemical parameters. The polluted soil (Control) sample had mean bacterial counts of 8.8x10⁴, 9.0x10⁴, 9.2´10⁴, 9.9x10⁴ and 7.6x10⁴ cfu/g respectively. Sample treated with NPK fertilizer had mean bacterial counts of 4.4x10⁴, 4.6x10⁴, 4.7x10⁴, 4.9x10⁴ and 5.2x10⁴ cfu/g on days 0,28,56,84 and 112 respectively; sample treated with poultry manure had mean bacterial counts of 1.6x10⁴, 1.8x10⁴, 2.0x10⁴, 2.4x10⁴ and 2.7x10⁴ cfu/g on days 0, 28,56,84 and 112 respectively; the saw dust treated sample had mean bacterial counts of 2.0x10⁴, 2.3x10⁴, 2.7x10⁴, 2.9x10⁴ and 3.0x10⁴ cfu/g on days 0,28,56,84 and 112 respectively while that treated with goat dung had mean bacterial counts of 9.3x10⁴, 9.5x10⁴, 9.6x10⁴, 9.8x10⁴and 9.9x10⁴ cfu/g on days 0,28,56,84 and 112 respectively.  There were differences in the physico-chemical analyses from the diverse samples. After statistical analysis (P£0.05) there was a significant difference between the different treated samples from the control. The results suggest that nutrient supplementation would be effective in the remediation of crude oil polluted soils.

The potentials of various treatment options for the bioremediation of crude oil polluted soils seems to hold the most immediate solution especially for use in areas that would be adversely affected by physical or other removal methods. In this study, the reduction of oil in the treated samples is evident, polluted samples supplemented with fertilizer and poultry manure respectively proved to be the best options during the 112 days study period. This study shows that those organic supplements containing nitrogen and phosphorus have great potentials for the remediation of soils contaminated with petroleum hydrocarbon within a reasonable time.

Keywords: Bioremediation, Crude Oil Polluted Soil, Organic Manure (poultry droppings and goat dung); Inorganic fertilizer (NPK 15:15:15), Saw dust.