Characterization and treatment of industrial laundry wastewaters: a review

The industrial laundry sector is a major user of water and chemicals such as surfactants, and one of the largest producers of wastewater. Although treated wastewaters comply with regulations, they still contain contaminants. Here we review laundry wastewater with focus on industrial laundry activities and their challenges, chemical composition of wastewater, and treatment techniques. We discuss advantages and drawbacks of treatment techniques that can be used as secondary treatment in already existing plants, or as tertiary treatment, i.e., complementary to an existing treatment. We observe that laundry is an expanding industrial sector with increasing water requirements, an abundant use of chemical substances, and increasingly stringent discharge regulations. There is a lack of chemical and biological knowledge on aqueous discharges. Moreover, the chemical composition, temporal variability, treatment information, and environmental and ecotoxicological data are poorly reported. The composition of wastewaters and additives, and their temporal variability are also poorly known. Similarly, detailed information on treatments is rare, and environmental and ecotoxicological data are poorly reported. Finding a tertiary water treatment process that is efficient, viable, and environmentally friendly is challenging since wastewater volumes are very high and contaminants are present at trace level in complex organo-mineral mixtures.