RESTORATION OF A MODEL OIL-POLLUTED SOIL USING CASSAVA-MILL EFFLUENT

ABSTRACT

The efficiency of cassava mill effluent as a source of organic nutrients and chelates in the bioremediation of oil contaminated soil was investigated. This was done by assessing the percentage change of some parameters in the spent lubricating oil (SLO) polluted soil, amended with cassava mill effluent (CME). The results showed a reduction in the hydrocarbon content of the polluted soils as well as selected heavy metals in the soils; suggesting the effectiveness of the chelate (oxalic acid) in the CME. There was a decrease in total organic carbon in the amended categories showing an increase in microbial activities stimulated by the CME. There was an increase in the colony forming unit (cfu) of microorganisms and this suggested an augmentation of microbial population and stimulation of their activities in the soil. The physiochemical analysis revealed increase in pH values, decrease in exchangeable cations and conductivity in the polluted soils. There was no weed in the polluted soils throughout the period of the experiment. This may be attributed to the concentration of the contaminant (at 10% w/w) in the soil, and which could have overwhelmed the soil microbial population, minimizing remediation activity. It is therefore suggested that a longer time of exposure is required for reasonable remediation to take place.