Why Add Lime at Drinking Water Plant

Adding lime as a treatment chemical in drinking water plants is a common practice. Lime is a chemical compound made from calcium oxide or calcium hydroxide. When added to water, the lime reacts with the dissolved carbon dioxide, which increases the pH level of the water. The pH level is an essential component of water quality, and it affects the aesthetics, taste, and safety of drinking water. In this article, we will explore why lime is added to drinking water plants and its benefits.

Lime for pH Control

One of the primary reasons for adding lime to drinking water plants is to control the pH level of the water. The pH level indicates the acidity or alkalinity of water, and it ranges from 0 to 14. A pH level of 0 is highly acidic, while a pH level of 14 is highly alkaline. The ideal pH level for drinking water is between 6.5 and 8.5. If the pH level is below or above this range, it can cause significant problems. For example, low pH levels can lead to corrosion in the water distribution system, which can cause metal pipes to rust and leach into the water. High pH levels can cause the water to taste bitter and leave mineral deposits on plumbing fixtures. Lime is added to treat the water and raise the pH level to the desired range.

Lime for Softening Hard Water

In addition to pH control, lime is also used to soften hard water. Hard water is water that contains high levels of dissolved minerals such as calcium and magnesium. These minerals can cause scaling in pipes and appliances, reducing their lifespan and efficiency. They can also make soap less effective, making it harder to lather and rinse off. Lime is added to hard water to make the minerals insoluble, which helps to reduce the scaling and improve the soap's effectiveness. The process of adding lime to hard water is called lime softening, and it is a common treatment method used in water treatment plants.

Lime for Coagulation and Flocculation

Lime is also used in coagulation and flocculation during the water treatment process. Coagulation is the process of destabilizing the particles in the water, making them easier to remove. Flocculation is the process of bringing the destabilized particles together to form larger clusters or flocs. Lime is added to the water to create a chemical reaction that helps to coagulate and flocculate the particles. The flocs can then be removed from the water more easily by sedimentation and filtration. This process helps to remove impurities and suspended particles from the water, making it safer to drink.

Lime as a Disinfectant

Lime has disinfectant properties that help to kill bacteria and viruses in the water. When lime is added to water, it reacts with the impurities in the water, producing heat and a high pH level. This process can kill harmful bacteria and viruses that may be present in the water. While lime is not a primary disinfectant, it can be used in conjunction with other disinfectants, such as chlorine, to provide additional protection against waterborne diseases.

Conclusion

In conclusion, adding lime to drinking water plants is a common practice that serves many purposes. It helps to control the pH level of the water, soften hard water, coagulate and flocculate particles, and disinfect the water. These benefits help to ensure that the drinking water is safe, aesthetically pleasing, and free from impurities. While lime is a useful chemical for water treatment, it must be used in the correct amounts and under strict guidelines to avoid any adverse health effects. With proper use, lime can be a valuable tool in providing safe and clean drinking water to communities around the world.