What method is primarily used to reduce the levels of inorganic nutrients in wastewater?

Chemical precipitation is the method primarily used to reduce the levels of inorganic nutrients in wastewater due to its effectiveness in removing dissolved materials, particularly phosphates and some forms of nitrogen. This process involves the addition of specific chemicals, often referred to as precipitants, that react with the inorganic nutrients in wastewater, causing them to form solid particles. These solid particles can then be removed from the liquid phase through sedimentation or filtration.

For instance, when treating phosphorus, a common precipitant such as aluminum sulfate (alum) or iron salts can be added to the wastewater. These compounds form insoluble precipitates with phosphate ions, which can subsequently be separated. This process is crucial for wastewater treatment plants to meet regulatory standards for nutrient discharge, helping to prevent issues such as eutrophication in receiving water bodies.

In contrast, while methods like filtration, biological treatment, and polymer addition play important roles in wastewater treatment systems, they do not specifically target the removal of inorganic nutrients through the same chemical processes that characterize precipitation. Filtration is generally more effective for removing suspended solids rather than dissolved nutrients, while biological treatment relies on microorganisms, which are better suited for organic matter removal rather than directly addressing inorganic nutrient concentrations. Polymer addition may assist in enhancing sedimentation but is not primarily