1. Which of the following is not a probable cause for excessive sloughing in a rotating biological contactor?
a. Toxic material in the influent
b. Excessive pH changes
c. Excessive changes in flow and/or organic loading
d. High dissolved oxygen levels
2. Which of the following is the device used for level measurement?
a. Parshall flume
b. Bubble tube
c. Venture meter
3. A positive displacement pump should never be started _.
a. With the discharge valve open
b. Before relieving all pressure in the discharge pipe
c. With the discharge valve closed
d. Without being primed
4. A sludge suction manifold is a component of a(n) _.
a. Grit classifier
b. Aerobic digester
c. Rapid sludge return (RSR) clarifier
d. Plate and frame press
5. Hypoclorite (OCl-) and hypochlorous acid (HOCl) constitute _.
a. Chlorine demand
b. Free residual chlorine
c. Combined residual chlorine
d. Total residual chlorine