What is the main objective of primary treatment in wastewater management?

The main objective of primary treatment in wastewater management is to remove settleable solids and reduce biochemical oxygen demand (BOD). This process typically involves physical methods such as sedimentation, where heavier solids settle to the bottom of a treatment tank, allowing for the removal of these solids from the wastewater. By effectively removing these impurities, primary treatment helps to decrease the overall pollutant load entering subsequent treatment stages, thereby enhancing the efficiency of the treatment process.

Reducing BOD is crucial because it reflects the amount of organic material present in wastewater. High levels of BOD can lead to adverse environmental effects if discharged untreated into water bodies, such as decreased oxygen levels and harm to aquatic life. Therefore, by focusing on the removal of settleable solids and reducing BOD, primary treatment plays a vital role in protecting the environment and improving water quality.

The other options, while essential aspects of wastewater treatment, do not align with the main goal of primary treatment. Stabilizing pH, disinfecting wastewater, and ensuring nutrient balance pertain to other stages in the treatment process or specific goals rather than the primary treatment phase itself.