Which methods can reduce the level of fluorides in drinking water?

The methods listed in the first choice—coagulation, lime softening, and ion exchange—are effective techniques for reducing fluoride levels in drinking water.

Coagulation involves adding chemicals to water that bind with pollutants, including fluoride. These chemicals help to form larger particles that can then be easily removed during the subsequent sedimentation or filtration processes. Lime softening, on the other hand, introduces lime (calcium hydroxide) to the water, which not only reduces hardness but can also precipitate fluoride when certain conditions are met, allowing it to be removed from the water. Ion exchange is another widely used method where fluoride ions in the water are exchanged for less harmful ions, effectively reducing fluoride concentration.

These methods are well-supported by engineering practices and scientific studies for their efficiency in treating water for fluoride removal, making them reliable choices for public drinking water systems that need to manage fluoride levels to meet health standards.

While other methods, such as reverse osmosis, can effectively reduce fluoride levels, they tend to be more expensive and are typically used for more specialized applications rather than widespread water supply treatment. Other combinations involving filtration and chlorination do not directly target fluoride reduction, nor do electrolysis and sedimentation directly address fluoride removal in a manner comparable to