1. Nitrification inhibition may begin when the alkalinity level drops below _ mg/L as CaCO3.
a. 50
b. 60
c. 75
d. 100

2. The nitrification unit effluent COD shows a sudden increase. The probable cause is _.
a. decrease in effluent BOD.
b. Excessive addition of methanol
c. lack of nitrate in effluent
d. reduction in suspended solids

3. Industrial waste that can be treated by biological process includes _.
a. metal finishing waste
b. paper product waste
c. plating waste
d. pesticide waste

4. A major characteristic of a metal-plating waste is high _.
a. BOD
b. organic matter
c. suspended solids
d. toxicity

5. The precipitate in coagulation with alum is aluminum _.
a. bicarbonate
b. carbonate
c. hydroxide
d. sulfate

Answers:

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