During the last 30 years, environmental issues about the chemical and biological contaminations of water have become a major concern for society, public authorities and the industry. Most domestic and industrial activities produce wastewaters containing undesirable toxic contaminants. In this context, a constant effort must be made to protect water resources. Current wastewater treatment methods involve a combination of physical, chemical and biological processes, and operations to remove insoluble particles and soluble contaminants from effluents. This article provides an overview of methods for wastewater treatment, and describes the advantages and disadvantages of available technologies.