1. SVI levels are approximately _ for ideal operations.
a. 200 mg/L
b. 100 mg/L
c. 150 mg/L

2. For a conventional activated sludge process, the Food:Microorganism ratio should be in the range of _.
a. 2.0 to 5.0
b. 0.01 to 0.07
c. 0.2 to 0.5
d. 0.07 to 0.15

3. What is the minimum recommended D.O. in an aeration tank for biological nitrification?
a. 0.5 mg/L
b. 1.0 mg/L
c. 1.5 mg/L
d. 2.0 mg/L

4. The advantage of using a constant return activated sludge flow control is _.
a. variations in the MLSS are reduced
b. F:M varys more than with the constant rate RAS control
c. MLSS remains in the clarifier too long
d. clarifier is subjected to maximum solids loading at peak flows
e. none of the above

5. What gas is heavier than air, not detectable at high concentrations and is flammable?
a. hydrogen sulfide
b. methane
c. carbon monoxide
d. argon

Answers:

1. b
2. c
3. b
4. e
5. a