Abstract

Bioremediation of soil polluted with palm oil mill effluent (POME) was carried out using microorganisms found in organic wastes in Anyigba, Kogi State. Pollution and bioremediation studies were carried out in the laboratory by polluting soil with raw palm oil mill effluent (POME) and subsequently amended using 20% of a 1:1 mixture of cow dung and chicken droppings. Bioremediation of the polluted soil was monitored using gas-chromatography mass spectroscopy (GCMS) analysis of the petroleum ether extracts of the POME, unpolluted, POME polluted, and bioremediated polluted soil at one and two months. Fats and fatty acids and derivatives were found in the POME and soil extracts. After one month, the GC-MS analysis showed a predominance of fatty acid esters (97%) and the presence of squalene. At the end of two months, most of the esters were converted to fatty acids, while squalene was probably cyclized to give two important triterpenoids, lupeol, and lanosta-8, 24-dien-3-ol, acetate. Thus, during pollution, there were chemical transformations, particularly oxidation of alkanes to carboxylic acids, followed by esterification to give esters which were utilized by microorganisms in the soil. After bioremediation of the polluted soil for 2 consecutive months, the GC-MS analysis showed the presence of a large number of alkylbenzenes, constituting about 41.52% of the extract at the end of the first month. The alkylbenzenes were subsequently degraded or utilized by microorganisms in the organic wastes at the end of two months to give essentially C-8 aliphatic compounds that are less polluting than the long-chain fats, fatty acids, and derivatives. The results suggest that chemical transformations that occurred during the bioremediation process generated less toxic or non-toxic components, which microorganisms in the POME polluted soil could consume and therefore, make the soil suitable for plant growth.