What is Removed from Waste Water at Water Treatment Plants

Water treatment plants are responsible for treating and purifying the waste water that is generated by households, businesses and industries. The treatment process involves removing pollutants and contaminants to ensure that the water is safe for discharge into the environment or for reuse. The specific type of treatment used depends on the quality of the water and the intended use. This article explores the various elements that are removed from waste water at water treatment plants.

Suspended Solids

Suspended solids are particles that are visible to the eye and remain suspended in water. These solids include sand, silt, and clay, as well as other organic and inorganic materials that are too small to be removed by filtration alone. At water treatment plants, suspended solids are removed by a process called sedimentation. During this process, the water is allowed to sit in large tanks or settling basins, allowing the heavier solids to sink to the bottom. These solids are then removed from the bottom of the basin and dried for disposal.

Pathogens and Microorganisms

Pathogens and microorganisms are present in human and animal waste and poses a risk to public health if not properly removed from waste water. Chlorination is the most common method for killing bacteria, viruses, and other harmful organisms in waste water. This process involves adding chlorine to the water, which reacts with microorganisms, killing them off. The water is then dechlorinated to remove any traces of residual chlorine before being discharged into the environment or reused.

Chemicals and Heavy Metals

Industrial and agricultural activities can introduce a range of chemicals and heavy metals into the waste water supply. These chemicals and heavy metals can be harmful to plants, animals, and humans, and must be removed through a process called chemical precipitation. Chemical precipitation involves adding chemicals such as lime, ferric chloride, or alum to the water, which react with the chemicals and heavy metals to form solids. These solids can then be removed through sedimentation or filtration.

Nutrients

Nutrients such as nitrogen and phosphorus can also be present in waste water and contribute to the growth of algae in water bodies. This growth can create dead zones, where oxygen levels are depleted, and aquatic life cannot survive. To remove excess nutrients from waste water, biological treatment is used. Biological treatment involves introducing bacteria that consume and break down organic matter, converting it into carbon dioxide and water. These bacteria can be naturally occurring or added to the water in the form of bacteria cultures.

Conclusion

Water treatment plants play a critical role in ensuring that waste water is treated and purified before being discharged into the environment or reused. By removing suspended solids, pathogens and microorganisms, chemicals and heavy metals, and excess nutrients, water treatment plants help protect public health and preserve the natural environment. As such, it is essential to continue improving and investing in water treatment processes to ensure that our water supply remains clean and healthy for generations to come.