Which chemical is commonly used for treating water for phosphorus removal?

Ferrous sulfate is commonly used for treating water to remove phosphorus because it acts as a coagulant that can effectively precipitate phosphate in the presence of oxygen. When ferrous sulfate is added to wastewater, it reacts with hydrogen sulfide and phosphate ions, forming insoluble iron phosphates that can be removed through sedimentation or filtration. This reaction lowers the concentration of phosphorus in the water, which is vital for preventing issues such as algal blooms in receiving waters.

Alum, while effective for phosphorus removal, is used more broadly for coagulation and sedimentation processes. Calcium carbonate and sodium bicarbonate are primarily employed for pH adjustment and alkalinity supplementation rather than directly targeting phosphorus removal. Therefore, ferrous sulfate stands out as the preferred choice for specifically addressing phosphorus reduction in water treatment processes.