What process helps to increase the dissolved oxygen in water during treatment?

Aeration is the process that effectively increases the dissolved oxygen in water during treatment. This process involves introducing air or pure oxygen into the water, which allows oxygen to dissolve into the water. The primary objective of aeration is to enhance the water quality by promoting the growth of aerobic microorganisms that break down organic matter, thereby improving overall water sanitation.

In water treatment facilities, aeration can take place in various ways, such as in aeration tanks, surface aerators, or diffused aerators. By increasing the dissolved oxygen levels, the treatment process also helps improve the efficiency of biological treatment methods, such as activated sludge processes, enabling them to work more effectively in removing contaminants.

The other processes mentioned do not primarily focus on increasing dissolved oxygen levels. For instance, filtration removes suspended particles but does not add oxygen. Chlorination is used for disinfection and may even lower dissolved oxygen levels temporarily due to the chemical reactions involved. Coagulation assists in clumping together small particles for easier removal, but again, it does not directly pertain to increasing dissolved oxygen in the water. Therefore, aeration stands out as the correct answer for enhancing dissolved oxygen content in treated water.