Which process is considered primary treatment of water?

Primary treatment of water is a critical step in wastewater management, designed to remove a significant portion of suspended solids and organic matter from wastewater before further treatment processes are applied. This treatment typically involves physical methods that separate solids from the liquid phase.

The process identified as the correct answer includes the use of a bar screen, grit chamber, and primary clarifier. Each component plays a vital role in the primary treatment stage. The bar screen captures larger debris and solids to prevent equipment damage and clogging, while the grit chamber allows heavier particles like sand and gravel to settle out due to gravity. Following these steps, the primary clarifier further separates remaining suspended solids from wastewater through sedimentation, where solids settle to the bottom as sludge.

In contrast, the other options listed represent secondary or tertiary treatment processes or are not limited to primary treatment. Filtration and reverse osmosis are advanced techniques used primarily in the later stages of wastewater treatment for further purification. Biological aeration is a process associated with secondary treatment, which uses microorganisms to break down organic matter. Chlorination and sedimentation typically relate more to disinfection and not to the initial removal of solids in primary treatment.

Thus, the correct answer reflects a straightforward physical process aimed at reducing the load of pollutants in wastewater through