What is the function of alum in water treatment?

Alum, primarily aluminum sulfate, is widely used in water treatment processes specifically for its coagulating properties. When added to water, alum works by forming microscopic particles called flocs that can aggregate with suspended solids and particulates, facilitating their removal from the water. This process is essential in reducing turbidity, which is the cloudiness or haziness caused by large numbers of individual particles. By enhancing the formation of these flocs, alum effectively gathers turbidity-causing materials together, allowing for easier sedimentation and filtration, ultimately leading to clearer, cleaner water.

The other options do not accurately reflect the main purpose of alum in water treatment. Lowering the temperature of water, acting as a disinfectant, or increasing mineral content are not aligned with the key role of alum. Its primary and recognized function is as a coagulant, making it indispensable in managing water quality.