What is the main purpose of a rapid sand filter in water treatment?

The main purpose of a rapid sand filter in water treatment is to remove suspended solids and lower turbidity. This filtration process involves passing water through a bed of sand at a rapid rate, which effectively traps and separates particles from the water. As water flows through the filter, larger suspended particles are captured in the upper layers of sand, while smaller particles penetrate deeper, ensuring that the water emerging from the filter is clearer and of higher quality.

This reduction of turbidity is crucial because high turbidity can harbor harmful microorganisms and impair the effectiveness of disinfection processes. By effectively reducing suspended solids, rapid sand filters pave the way for subsequent treatment processes, improving overall water quality.

Other choices do not reflect the primary function of rapid sand filters. While disinfection is essential and involves chemicals, it occurs separately in the water treatment process after filtration. Increasing water temperatures is generally not a function of rapid sand filtering, and filtering out dissolved gases falls outside the scope of what a sand filter is designed for.