Quantitative and qualitative analysis of wastewater from vehicle washing facilities

Vehicle washing facilities generate considerable volumes of wastewater containing organic matter, hydrocarbons, heavy metals, surfactants and microbial contaminants, requiring appropriate treatment prior to discharge or reuse. This study evaluates water consumption and wastewater quality at two Spanish facilities with distinct operational characteristics: Montfullà, serving predominantly industrial vehicles, and Miramón, focused on passenger cars. Over a three-year monitoring period (2015–2017), more than 60 sampling campaigns were conducted at each site to assess key physicochemical and microbiological parameters. Water consumption averaged 275.3 L/vehicle at Montfullà and 307.5 L/vehicle at Miramón, reflecting differences in washing programs and vehicle typology. Montfullà exhibited higher pollutant concentrations, with suspended solids reaching 412 mg/L, hydrocarbons up to 13.9 mg/L, and zinc up to 0.71 mg/L. COD and BOD5 values were significantly higher at Montfullà, indicating a greater organic load. Both facilities showed moderate biodegradability (BOD5/COD ≈ 0.3). Escherichia coli concentrations averaged approximately 103 CFU/100 mL at both sites, exceeding reuse standards and highlighting the need for effective disinfection. The results demonstrate that vehicle type and operational practices strongly influence wastewater composition. Although water recycling practices were implemented at both facilities, additional treatment is required to comply with regulatory standards for safe discharge or reuse. Nature-based solutions and advanced treatment technologies represent promising strategies to enhance sustainability in vehicle washing facilities.