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
d. Magmeters

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

Answers:

1. d
2. b
3. c
4. c
5. b