1. Following coagulation, the next step in physical-chemical treatment is called _.
a. brownian
b. destabilization
c. flocculation
d. precipitation

2. In order to get coagulation to proceed, a chemical change process must occur which is called _.
a. brownian
b. destabilization
c. flocculation
d. precipitation

3. The solubility of metals increases as pH _.
a. increases
b. decreases
c. independent of pH
d. spreads

4. From a public health standpoint which of the following is the safest sludge for soil conditioning purposes?
a. sludge dried on drying beds
b. sludge produced from a vacuum filter
c. heat dried sludge
d. liquid raw sludge
e. liquid digested sludge

5. If the filter cake on a vacuum filter develops cracks just before it reaches the end of the drying zone, this indicates what?
a. the vacuum is too high
b. the filter is operating well
c. the sludge is not properly conditioned
d. the drum speed should be decreased
e. none of the above

Answers:

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