Problem: Odor complaints are increasing at the WWTP. The operator finds most odors seem to be coming from the primary clarifiers where bubbles and chunks of solids are found on the tank surface. What should be done to correct the problem? • Increase the pretreatment chlorine dosage • Cover the secondary clarifiers • Increase the sludge withdrawal from the primary clarifiers • Add potassium permanganate or hydrogen peroxide to the upstream lift stations