Heavy metal contamination from fuel station run-off and carwash wastewater: An assessment of ecological risk and experimental treatment.

Fuel station run-off (FSR) and carwash wastewater (CWW) are potential sources of heavy metals contamination in surface waters. High levels of heavy metals can have dire consequences on the ecosystem in receiving waterbodies. Ghanaians demand (and supply) of fuel and vehicle cleaning services has increased sharply with population and economic growth and the trend will continue. In this study, a microwave plasma atomic emission spectrometer was used to analyze the levels of Cr, Cu, Ni, Pb, and Zn in CWW and FSR from ten fuel stations and ten carwash facilities in the Oforikrom and Ejisu Municipalities in the Ashanti Region of Ghana. An experimental sand filter bed augmented with charcoal was used to treat the CWW and FSR. The efficacy of the treatment and the potential ecological risk posed by the untreated CWW and FSR were assessed using single- (contamination factor, CF) and multi-element ecological risk indicators (potential ecological risk index, PERI). The findings showed that CWW contained 0.07 mg/L Cr, 0.20 mg/L Cu, 0.02 mg/L Ni, 1.16 mg/L Pb, and 0.58 mg/L of Zn, while, FSR contained 0.05 mg/L Cr, 0.09 mg/L Cu, 0.17 mg/L Ni, 0.31 mg/L Pb, and 0.18 mg/L Zn. Copper levels in CWW and FSR were positively correlated (0.8), suggesting similar sources of contamination. CF revealed that Cr, Cu, Ni, and Zn in CWW and FSR posed low to medium risk, while Pb posed high risk. The PERI also ranked Pb in all samples as extreme pollution, and Ni as severe pollution in FSR. The charcoal augmented sand filter effectively removed Pb (96%), Cu (61%), and Zn (79%) in both CWW and FSR. Therefore, Ghana EPA and Department of Urban Planning policies should include the construction of a charcoal-augmented sand filtration system at FS and CW facilities to intercept and treat wastewater and run-off before discharge.