Definition of water treatment
Water treatment refers to the process of improving water quality by adopting physical, chemical, biological and other methods in order to make water quality meet certain standards for use. Traditionally, water treatment mainly includes water supply treatment and wastewater treatment. The treatment of taking water from water sources such as rivers, lakes, and reservoirs for drinking is called water supply treatment. The treatment of used water is called wastewater treatment. With the increasingly serious water pollution, natural clean water resources are becoming more and more limited. From the perspective of comprehensive recycling and utilization of water resources, the boundary between water supply treatment and wastewater treatment is no longer very clear. Wastewater can be used as a water source, and after treatment, it can be used for industrial water or even domestic water. The emergence of terms such as reclaimed water, recycled water, etc. reflects this situation.
Categories of water treatment
On the whole, water treatment methods can be divided into two categories: physical chemical methods and biological methods (also known as biochemical methods). Among them, the physicochemical method usually includes three situations: (1) only physical changes occur during the treatment process; (2) only chemical changes occur during the treatment process; (3) both physical and chemical changes occur during the treatment process. Among the common water treatment technologies, coagulation sedimentation, filtration, air flotation, membrane separation, adsorption, ion exchange, magnetic separation, etc. are all physical and chemical methods; breakpoint chlorination, ozone oxidation, advanced oxidation, zero-valent iron reduction, etc. Belonging to chemical redox methods: activated sludge method, biofilm, membrane bioreactor, biological filter, etc. are all biological methods. In addition, most of the biochemical treatment technologies will produce excess sludge due to the use of activated sludge. The treatment and disposal of sludge belongs to the associated field of water treatment, especially sewage biochemical treatment.
