What is the purpose of a blowdown in a cooling tower system?

In a cooling tower system, blowdown serves a critical purpose in managing water quality and efficiency. The primary function of blowdown is to remove a portion of the water that has accumulated dissolved solids, which can include minerals and other contaminants. Over time, as water circulates through the cooling tower, these solids can concentrate, leading to issues such as scaling, corrosion, and biological growth.

By performing blowdown, dissolved solids are effectively removed from the system, helping to maintain optimal water quality. This directly relates to the second option regarding the removal of dissolved solids.

Additionally, blowdown plays a crucial role in managing chemical concentrations. In order to keep the balance of treatments, such as biocides or scale inhibitors, at appropriate levels, it is necessary to perform blowdown to prevent the overconcentration of these chemicals. High chemical concentrations can lead to negative effects on system performance and water quality.

Thus, the purpose of blowdown effectively encompasses both the removal of dissolved solids and the management of chemical concentrations, validating the choice that includes both aspects as the correct answer.