Water is used both domestic as well as industrial use in large quantities. After using the water, it is then released to the environment as wastewater. Wastewater is used as a medium of removing other forms of waste from homes and industries. The wastewater carries both organic and nonorganic substances which can be harmful to the environment in various ways. It, therefore, becomes necessary to take the water through a waste water treatment plant to remove these components. The end product is clean water, harmless salts, and carbon dioxide. Learn more about sewage treatment plants, go here.
The whole processor of treating water is done in three stages. The primary stage involves removal of solid suspensions and floating wastes. It includes trapping the solids and sedimentation by gravity. It is sometimes referred to as mechanical treatment of wastewater. However, chemicals can be used to increase the speed of sedimentation. It can reduce the BOD by around 20-30% and the sold by 50-60%. It is the fort stage of water treatment. As the wastewater increases, the complexity of this stage also increases. Find out for further details on wastewater treatment plant process right here.
The second stage is referred to as the biological stage. It involves removal of dissolved organic matter that has not been captured in the primary stage. There is use of microbes to consume the organic matter as food. It is converted to carbon dioxide and water and energy for the microbes which they use to grow and reproduce. It is then followed by additional settling tanks to remove suspended solids. *5% of the suspended solid and BOD are removed in the second stage of a well running sewage treatment plant. This treatment stage involves activated sludge process, ponds and wetland systems, trickling filters among other forms of water treatment.
The third stage is referred to as a tertiary treatment. A well-running wastewater treatment plant can remove 99% of water impurities. The resultant water is a drinking water quality. The technology used in sophisticated expensive and not readily available. It also requires high level of training. A steady supply of energy is required to run the system. Various equipment and chemical are used for this stage. Some tertiary treatment plants are a modification of the secondary treatment to remove nitrogen and phosphorus chemicals. Typically, there is disinfection using chlorine before the water is discharged to the river. There are some concerns that chlorine could also become another problem and some water treatment companies are moving away from its use. Take a look at this link https://en.wikipedia.org/wiki/Sewage_treatment for more information.