1. A benefit in using fixed film reactors is that _.
a. biomass is visible to the operator
b. odors are not a problem
c. snails help degrade organic matter
d. temperature variations do not influence performance of process

2. When leaving a filter out of service for several days or longer, the excessive material (biomass growths) on the media should be _.
a. fed continuously
b. kept alive
c. recirculated from the clarifier
d. removed from the media

3. A secondary clarifier must be provided after an RBC for _.
a. disinfection of treated wastewater
b. recycling a biological sludge directly to RBCs
c. removal of sloughed solids from the treated wastewater
d. treatment of scum

4. An important aspect of proper operating control of fixed growth processes is that biologically produced solids should be _.
a. disinfected prior to disposal
b. discharged in the plant effluent
c. returned as quickly as possible to the process
d. wasted at a controlled rate

5. Trickling filter rock media must be carefully graded to ensure _.
a. BOD removals are maximized
b. media does not deteriorate rapidly
c. media does not fall into and plug the underdrain system
d. small or fine material does not plug the void space

Answers:

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