Exploring the Potential in LID Technologies for Remediating Heavy Metals in Carwash Wastewater

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.

A Review of On-Site Carwash Wastewater Treatment

In recent years, people’s environmental awareness has increased. The high density of the urban population has caused a considerable increase in the demand for car washing services, which has created large quantities of car wash wastewater. The main pollutants in car wash wastewater are detergents, dirt, oil, and grease. Untreated wastewater released into rainwater sewer systems or other water bodies may pollute the water and generate excessive bubble foams, which negatively affects urban appearance. Car washes are divided into mechanical car washes and manual or self-service car washes. In general, car washes have a small operation and scale, occupy limited land, and cannot afford wastewater treatment costs. Therefore, most car washes are not equipped with wastewater treatment facilities. Consequently, the discharge of wastewater from car washes negatively affects the water quality in the surrounding environment and results in wasteful use of water resources. This study reviewed 68 research papers on the quality, treatment techniques, treatment costs, and treatment effectiveness of car wash wastewater to provide a reference for car wash operators to contribute to the preservation of water resources. We found that there is a higher chance of recycling car wash wastewater when combing two different techniques for car wash wastewater treatment.