Application of flocculation–flotation followed by ozonation in vehicle wash wastewater treatment/disinfection and water reclamation

Abstract

This article provides the results of flocculation–flotation followed by sand filtration and ozonation (FFO), applied for the treatment of car wash wastewater in a water reclamation system in Brazil. The assessment of the efficiency of the process in enhancing reclaimed water quality, especially aesthetic, microbiological, and chemical issues is reported. The FFO process provided disinfected (Escherichia coli < 1.8 CFU 100 mL−1) and clarified water (10 NTU), minor foaming (residual surfactants = 1.30 mg L−1MBAS), and no odor-related problems from reclaimed water. Comparative studies were carried out at bench scale; ozone (AOP) and chlorine were applied separately as oxidation procedures and a mass balance was assessed as a function of the number of water cycles. Results revealed that besides higher oxidation of organics and water clarification, both conductivity and dissolved solids concentrations for the ozone-treated water were lower than those obtained with the chlorinated water. A cost–benefit analysis performed for two different Brazilian scenarios showed that the payback period of the FFO equipment might be as short as one year, depending on water prices and daily wash demand. Thus, it appears that the FFO process has a great potential to be gradually introduced in sustainable vehicle wash water reclamation systems both in Brazil and worldwide.