What should be monitored to ensure screens operate effectively?

• A. Constant mixing rate
• B. Chlorination level
• C. Dissolved oxygen concentration
• D. Proper velocities, headloss, clean often

Answer: (D)

Monitoring flow velocity, headloss, and cleaning frequency keeps screens operating effectively. The velocity of water approaching the screen needs to be within a proper range: too fast can push solids through or cause damage; too slow can lead to solids settling and forming a clogging layer that reduces flow and screen efficiency. Headloss, the pressure drop across the screen, rises as the screen fouls; tracking this helps determine when the screen is near capacity and needs cleaning or backflushing. Regular cleaning restores open area for flow and maintains solids removal performance.

Other options relate to different parts of the treatment process that don’t reflect screen performance: constant mixing rate affects mixing in basins, while chlorination level and dissolved oxygen concentration pertain to disinfection and aeration rather than the screen’s physical operation.