Papers by Author: C.N. Owabor

Abstract: Polycyclic aromatic hydrocarbons occur naturally in petroleum oil and coal and the burning of fuel and the activities of paper mills also release these compounds to the environment. Batch experimental adsorption study for both soil fractions was conducted in a soil slurry system at ambient temperature, using <0.02mm particle sizes. Comparison was made of the linear least-squares method and a trial-and-error nonlinear method of some widely used isotherm models for the adsorption of naphthalene on clay and silt fractions. The experimental results were fitted to the Langmuir, Freundlich, Radke-Prausnitz, Sips, Temkin and Redlich-Peterson isotherms to obtain their characteristic parameters of each model. The coefficient of determination obtained from the different models using the linear method showed that Freundlich isotherm had the highest values for both clay and silt soil fractions with values of 0.843 and 0.897 respectively. The equilibrium data did not fit the Langmuir isotherm with values of 0.287 and 0.021 for clay and silt soil respectively. Using the nonlinear method the equilibrium data gave good fit for Radke-Prausnitz, Sips, Temkin and Redlich-Peterson isotherms. Sips isotherm gave the best fit for silt soil with the r² value of 0.9779 and this was followed by Temkin isotherm for clay soil with the value of 0.9673.

Abstract: Bioremediation as a strategy of clean- up of crude oil spills in water using a mixed microbial population of E. Coli, Aspergillus niger, Penicillum notatum and Pseudomonas aeruginosa was investigated in this study. The sample of crude oil polluted water containing the mixed microbes and the control was monitored for parameters such as BOD, pH, Total Hydrocarbon Content (THC) and Turbidity over a period of nine weeks. At the end of the bioremediation period, the results obtained showed that the sample remediated with the mixed microbes gave a THC drop from 14975mg/l -1.960mg/l (99.9% drop) compared to the control with a drop from 14975 – 18.72mg/l (99.8% drop). A BOD drop from 1447.4mg/l – 17.1mg/l (98.8% drop) for the sample mixed microbes and 1447.4 – 90.8mg/l (93.7% drop) for the control. Turbidity values increased from 5.0 NTU – 25.2NTU for sample with mixed microbes and 5.0 NTU – 23.1 NTU for the control. The values of THC (1.96 mg/l) and BOD (17.1 mg/l) at the end of the experimentation period fell within the FEPA and DPR limits of 10mg/l and 30mg/l for THC and BOD respectively.The results above thus indicates that the use of mixed microbial population of Pseudomonas aureginosa, Penicillium notatum, E. Coli and

Abstract: This paper investigates the use of redox parameters as a measure of the environmental impact assessment of soil contaminated with polycyclic aromatic hydrocarbons. The levels of naphthalene and anthracene which were used as model contaminants in the soil were periodically monitored along with ferric sulphate and nitrate at ambient conditions. The Brucine and Gelatin Barium methods were employed in estimating the nitrate and sulphate reductions. Experimental results revealed that the microbial utilization of nitrate was faster than that of sulphate; an indication that nitrate is the basic nutrient which provides nitrogen for the metabolic processes occurring during soil remediation. The percentage absorption for both nitrate and sulphate was comparatively higher for the soil unimpacted with polycyclic aromatic hydrocarbons, approximately 49.3% and 26.12% respectively. The percentage absorption of nitrate and sulphate for soil spiked independently with naphthalene and anthracene was found to be 42.18%; 31.21% and 22.93%; 19.74% respectively. The percentage reduction of naphthalene and anthracene in the nitrate and sulphate enhanced soil was 47.5%; 43.1% and 42.5%; 36.5% respectively. These results further affirm that the higher the molecular weight of the polycyclic aromatic hydrocarbon, the slower the rate of its degradation.