What is the main purpose of adding coagulants in wastewater treatment?

The main purpose of adding coagulants in wastewater treatment is to facilitate the settling of solids. Coagulants are chemical substances that promote the aggregation of fine particles and colloids suspended in water. When coagulants are introduced into the wastewater, they neutralize the charges on these particles, enabling them to clump together into larger aggregates called flocs. These larger flocs can then settle more easily due to their increased mass, which allows for the efficient removal of suspended solids during the sedimentation process.

This step is critical in wastewater treatment because it helps reduce the turbidity of the water and prepares it for subsequent treatment processes. By promoting solid-liquid separation, coagulants play a crucial role in achieving cleaner effluent that meets environmental standards.

The other options do not capture the primary purpose of coagulants. For example, while nutrient removal can be a component of overall water treatment, it is not the direct role of coagulants. Coagulants are specifically aimed at solid removal rather than merely increasing turbidity or deodorizing water, which are separate processes in wastewater treatment.