Oil contaminated soils around refined petroleum products depot and retailing stations were investigated for selected polycyclic aromatic hydrocarbons (PAHs) to determine their levels in the soils. Soil samples were collected using standard analytical procedures and the petroleum hydrocarbons extracted using standard method, while the PAHs (benzo[a]pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, and anthracene) contents of the extracted petroleum hydrocarbons were determined using SNR 8126 gas chromatograph equipped with a flame ionization detector (FID). The results indicated that benz[a]anthracene has the highest concentrations in both the oil depot contaminated soils (59.1 ± 3.3 mg/kg) and oil retailing station contaminated soils (20.8 ± 2.1 mg/kg). The results also showed that the oil depot contaminated soils were burdened with the analyzed PAHs than oil retailing station contaminated soils; this was confirmed by the results of t test analysis. Comparison of the values of the PAHs in the oil impacted soils with their background levels showed that their values in the two sets of oil impacted soils were excessive; this was corroborated with their high pollution (PI) and geoaccumulation (I geo ) index values, except chrysene, which moderately polluted the soils (low PI and I geo values); this was clear indication of indiscriminate discharge of petroleum fuels and petrochemicals into the soils.

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Groundwater quality and its potential health risk around a municipal dumpsite in Ikire, Southwest Nigeria was investigated using ten groundwater samples which were analyzed for physicochemical parameters. The methods used were groundwater sampling, analyses, spatial distribution of heavy metal (Cd, Cr, Cu, Fe, Mn, Pb, and Zn) and quantitative health risk analysis using USEPA equations. The chronic daily intake (CDI), hazard quotient (HQ), and hazard index (HI) were used to examine potential human health risks of heavy metal pollution. The mean concentration values of Cl − , Ca 2+ , K + Mg 2+ , Fe, Cd, Pb and Mn were higher than their respective permissible limits, while the mean concentration values HCO 3 − , Cu and Zn were within their respective limits. The HQ values of the heavy metals via oral ingestion for the children and adults are found in the order: Cd > Pb > Mn > Fe > Zn > Cu and Cd > Pb > Mn > Zn > Cu > Fe, respectively. The HI values via ingestion pathway for all heavy metals were beyond the threshold value of 1.0, indicating high contamination adverse health risk due to an undesirable level of heavy metals. Cadmium is a major contributor to non-cancer effects in children and adults in the groundwater samples in the region. The groundwater is unsafe for drinking and should be treated before domestic consumption.

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This study aimed at developing a laboratory scale packed bed reactor (PBR) and evaluating its performance in re-refining of used lubricating oils. Used and unused motor oil samples of two brands (Mobil Super SAE 20W-50 and Total Quartz 5000 SAE 20W-50) were used in this study. The sorbent materials were a blend of diatomaceous materials in the same mass ratio. The compound types of the oils eluted from the PBR and those of used and virgin oil samples were studied for comparison. FTIR spectroscopy was employed to observe the variations in the types and nature of functional groups present in the various oils as well as to estimate the oxidation products of the oils using peak area increase (PAI). The constituent organic compounds were also identified and quantified using GC-MS. The results revealed that some of the compounds exist in different isomeric forms in the oil samples. The similarity in the classes of compounds is affirmed by their very similar FTIR spectra. GC-MS results indicated that the used oils contained the highest number of compounds, followed by the treated oils and also indicated similar treatment effects on the brands of lubricating oil. The study concluded that the developed reactor is a viable and sustainable technique for re-refining of used lubricating oils.