Water treatment is the process of improving the quality of water to make it appropriate for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation, or many other uses, including being safely returned to the environment. Water treatment removes contaminants and undesirable components, or reduces their concentration so that the water becomes fit for its desired end-use. The treatment process is crucial to human health and allows humans to benefit from both drinking and irrigation use.
There are different types of water treatment processes, depending on the source of water and its initial condition prior to being treated. The most common steps in water treatment include coagulation, flocculation, sedimentation, filtration, and disinfection. Water treatment plants may also use a process called ultrafiltration, where the water goes through a filter membrane with very small pores. After the water has been filtered, water treatment plants may add one or more chemical disinfectants to kill any remaining parasites, bacteria, or viruses.
The source of water and its initial condition prior to being treated usually determines the water treatment process. Whether drinking water comes from surface water sources, including rivers, lakes, and runoff from melting snow, or from groundwater drawn from aquifers, it has the potential for some level of contamination. Water treatment ensures that contamination is removed before the water is sent to homes and businesses.
There are seven major steps involved in the large-scale water treatment for urban municipal water supply, including screening, aeration, coagulation, flocculation, sedimentation, filtration, and disinfection. Each of these steps is described in detail in the article.
