Wastewater treatment technologies

Abstract Water is an essential component of all forms of life and is one of the most important natural resources on planet Earth. Wastewater refers to stormwater and urban runoff and includes all effluents (sewage or liquid waste) coming from institutions, hospitals, industries, households, etc. Thus wastewater is contaminated by many toxic substances that have been proven to be harmful to living organisms and hence needs to be treated before being released into the environment. The major goal of wastewater treatment is to minimize the load of harmful compounds prior to the discharge of water back into the environment. Such an approach requires restoration of the water supply and protection of the planet from the hazardous effects of toxins. Insufficient or improper wastewater treatment can have adverse environmental consequences and subsequently cause harm to aquatic and wildlife, and can eventually lead to contamination of drinking water. The composition of wastewater varies widely depending on the source and therefore different treatment strategies are applied. The majority of wastewater treatment methods can be categorized into two main groups: biological treatment and chemical/physical treatment. The first technique utilizes biological material and/or bacteria, and the second is based on physical processes or chemical reactions. This chapter provides a brief description of the types of wastewater and their properties as well as presents an overview of wastewater treatment methods including sedimentation, coagulation, solvent extraction, and biological treatment.