What chemical may be added to control phosphorus levels in wastewater?

Aluminum sulfate, commonly known as alum, is used in wastewater treatment to help control phosphorus levels effectively. When added to wastewater, alum reacts with phosphorus to form aluminum phosphate, which precipitates out of the water, thereby reducing phosphorus concentration. This process is particularly crucial because phosphorus can contribute to eutrophication in receiving waters, leading to harmful algal blooms and other ecological issues. By utilizing alum, treatment plants can enhance their performance in reducing nutrient loads before the effluent is discharged into the environment.

Sodium hydroxide, calcium carbonate, and magnesium chloride do not effectively reduce phosphorus levels in the same way alum does. Sodium hydroxide is primarily used for pH adjustment, calcium carbonate is mainly used to buffer pH and control acidity, and magnesium chloride can assist in coagulation but is not specifically targeted for phosphorus removal.