Texas Wastewater Class B Practice Exam

The correct choice, a mechanically raked bar screen, is commonly used in wastewater treatment processes to separate and remove large solids from raw wastewater. This device consists of a series of bars that allow water to pass through while catching and holding back larger materials, such as sticks, leaves, plastics, and other debris that can disrupt the treatment process. The mechanical raking action then helps to continuously remove the collected solids, ensuring that the water entering subsequent treatment stages is free of these larger contaminants.

Grit chambers serve a different purpose by allowing heavier particles, like sand and gravel, to settle out of the wastewater; they are not specifically designed for large solid removal. An aeration tank is used primarily for biological treatment, where microorganisms degrade organic matter, not for the initial separation of large solids. Settling tanks are used for sedimentation processes, typically for removing smaller suspended solids after they have been treated, rather than for the initial screening of large debris from raw wastewater.