In some cases, wastewater may contain excessive nutrients, particularly nitrogen and phosphorus, which can lead to eutrophication in receiving water bodies. To control these nutrients, various chemicals are employed. For nitrogen removal, plants might use materials like calcium nitrate or ammonium sulfate, while phosphorus removal can be achieved with the addition of iron salts or aluminum salts. The strategic use of these chemicals helps to mitigate environmental impacts and maintain water quality in natural ecosystems.