Primary treatment is responsible for removing what percentage of BOD from wastewater?

Primary treatment in wastewater management primarily focuses on removing solids and some organic matter from wastewater before it undergoes further treatment processes. During this stage, physical processes such as sedimentation are employed, where larger particles settle out of the wastewater.

In terms of biochemical oxygen demand (BOD) removal, studies and operational data indicate that primary treatment typically reduces BOD by approximately 30% to 50%. Therefore, stating that primary treatment removes around 35% reflects a realistic figure based on common practice and empirical evidence observed in wastewater treatment facilities. This allows for a significant reduction in pollution load before secondary treatment stages, which aim to further degrade organic material.

This understanding clarifies why the figure of approximately 35% is often cited in texts and standards relating to wastewater treatment effectiveness.