Which item is typically not removed by a bar screen during wastewater treatment?

During wastewater treatment, a bar screen is utilized as a mechanical filtering device to remove larger debris from influent water. This initial step is crucial, as it prevents damage to subsequent treatment equipment and enhances overall system performance.

The correct choice pertains to small dissolved particles, which are not typically removed by bar screens. Bar screens have openings that allow water to pass through while capturing larger items such as rocks, sticks, and plastic bottles. Dissolved particles are, by definition, small enough to remain in solution and pass through the bar screen without being filtered out.

Understanding the function of bar screens highlights the importance of each stage in the wastewater treatment process, ensuring that equipment can operate effectively and efficiently by managing solids and preventing clogs and other operational issues.