Which method is often used to remove solids in preliminary wastewater treatment?

The correct method used to remove solids in preliminary wastewater treatment is screening. Screening is an essential first step in the treatment process where larger debris and objects, such as sticks, leaves, plastics, and other solids, are physically removed from wastewater. This is typically achieved by passing the wastewater through screens or grates that allow water to flow while capturing larger solids, preventing them from causing damage to equipment or interfering with subsequent treatment processes.

This initial removal of solids is crucial because it helps protect pumps and treatment systems from clogging and reduces the load on downstream processes, making them more efficient. Other methods, while also integral to wastewater treatment, serve different purposes. For instance, filtration (which involves passing water through a medium to separate smaller particles) and sedimentation (which relies on gravitational settling to remove suspended solids) are typically used in later treatment stages. Oxidation, on the other hand, is a chemical process aimed at breaking down organic matter or pollutants rather than physically removing solids.