How does primary treatment differ from secondary treatment?

Primary treatment primarily involves the mechanical removal of large solids and particulate matter from sewage, such as debris and grit, through processes like screening and sedimentation. This stage is focused on separating solid particles from the liquid waste stream, allowing for a more manageable effluent.

Secondary treatment, on the other hand, is primarily concerned with the biological treatment of wastewater. It utilizes microorganisms to break down organic matter that remains after primary treatment. This biological process converts dissolved and suspended organic material into more stable substances, further purifying the water.

The stated answer accurately describes the distinct processes involved in primary and secondary treatment. Instead of dealing with dissolved materials, primary treatment focuses on the physical aspects of waste separation, while secondary treatment adds a biological dimension to the treatment process for a more thorough detoxification of wastewater. This distinction underlines the different purposes and mechanisms of each treatment stage in wastewater management.