Bioremediation of hydrocarbon contaminated soil using compost, NPK fertilizer and cattle bile as amendment materials

Thumbnail Image
Journal Title
Journal ISSN
Volume Title
The study seeks to investigate the extent of degradation of petroleum hydrocarbon contaminated soil by harnessing the remedial potential of compost, NPK fertilizer and cattle bile as amendment additives. A baseline study was carried out to determine the physicochemical properties (TPH, OM, TOC, pH, TN, P, K, and Moisture content) and the microbial load (THBC) of the contaminated soil and compost using appropriate methods. Homogenized soil (1000g) each was amended with 10.53 g of NPK fertilizer, 107.48 g of compost to achieve 0.2%, whereas to establish 0.4% nitrogen 23.87 g of NPK fertilizer and 243.54 g of compost as well as 2 ml of cattle bile were employed to establish different microcosm experiments such as; A, B, C, D, A2, B2, C2 and D2 including a control (devoid of afore-listed additives). The microcosm experiments were subjected to aeration thrice a week over six weeks of incubation, during which individual microcosm experiment was periodically sampled at two weeks intervals for analysis. The data of results revealed a sharp decrease in TPH concentration after two weeks and progressively decreased further over the subsequent sampling week periods during incubation; with a corresponding increase in the rate of hydrocarbon compounds removal. Microcosm B2 and the control (Ct1) emerged as the maximum and minimum rate of TPH components removal at the end of the bioremediation process as illustrated in the order; B2(98.43%) > B(94.87%) > C(94.64%) > A(94.14%) > D2(93.65%) > A2(93.57%) > C2(92.44%) > D(91.43%) > Ct1(79.57%). Generally it was observed that microcosms established at 0.4% nitrogen concentration exhibited higher rate of nitrogen consumption as compared to those microcosms established at 0.2% nitrogen concentration. In conclusion, biostimulation through homogenization, addition of moisture, compost, NPK fertilizer and inoculation of cattle bile, is a plausible approach to effect TPH components removal from contaminated soil. Microcosm B2 (1000 g contaminated soil + 0.2% fertilizer + cattle bile) evidently emerged as the best treatment option among the other nine microcosm experiments. Cattle bile, indeed possess remedial potential and function as biosurfactant to augment the biosurfactant produced by the bacterial population to enhance hydrocarbon degradation.
Dissertation Submitted to the Department of Environmental Science, Kwame Nkrumah University of Science and Technology in Partial Fulfilment of the Requirements for the Degree of Master of Science in Environmental Science College of Science May, 2013