What is the primary purpose of using alkaline chemicals like lime in treatment processes?

The primary purpose of using alkaline chemicals like lime in treatment processes is to remove phosphorus. Lime increases the pH of wastewater, which facilitates the precipitation of phosphorus as calcium phosphate. This process helps in reducing the concentration of phosphorus in the effluent, thereby preventing nutrient pollution in receiving waters, which can lead to problems like algal blooms.

While enhancing sedimentation, increasing alkalinity, and precipitating heavy metals are relevant keywords in wastewater treatment, the specific role of lime in actively reducing phosphorus makes it the most accurate answer in this context. The effectiveness of lime in this regard is tied to its ability to react chemically in the treatment process, enabling the formation of solid compounds that can be easily removed through further filtration or sedimentation processes.