Which of the following best describes the product of the reaction between coagulants and alkalinity?

The reaction between coagulants and alkalinity in water treatment processes is fundamental to the coagulation and flocculation stages, where dissolved particles and impurities in water are agglomerated into larger particles known as flocs. When coagulants, such as aluminum sulfate or ferric chloride, are added to water that has adequate alkalinity, they promote the formation of these clumps of solid particles, which are more easily removed from the water during sedimentation or filtration.

This agglomeration process is essential for improving water clarity and quality because it enables the removal of suspended solids, organic matter, and even some pathogens. The resultant flocs, which appear as clusters of solid particles, are what ultimately lead to the treated water being clearer and of higher quality. This is why the correct answer highlights the formation of a clump of solid particles as a result of the reaction between coagulants and alkalinity.