Certification Action Line features questions and answers typical of those appearing in Water Quality Association (WQA) certification examinations. Some answers may not satisfy everyone or every condition.

1. A multimedia filter containing gravel, manganese greensand and anthracite can be effective at removing suspended solids at sizes as small as:
a) 20-40 microns
b) 5-10 microns
c) 1-2 microns

2. Manganese greensand is not a good particle filter; rather its primary purpose is to remove iron.
a) True
b) False

3. The purpose of the top anthracite layer in multimedia filters is to _______.
a) provide a light layer that is easily backwashed
b) reduce surface plugging of the sand or greensand layers
c) alleviate load from the sand, allowing the sand to perform more effectively
d) all of the above

4. Gravel layers in multimedia filters are used to _______.
a) distribute backwash flow evenly across the cross sectional area of the filter media bed
b) capture the most coarse turbidity particles
c) provide forceful scouring to scrub tenacious foulants from sand grain surfaces
d) all of the above

5. Reverse osmosis systems produce higher quality product water when pretreatment to control scale is by _______.
a) acid addition
b) ion exchange water softening
c) no difference between a or b regarding the resultant RO product water

6. Double pass reverse osmosis (permeate from the first pass is used as feed for the second pass) provides water free of bacteria.
a) True
b) False

7. The regular sanitization of industrial and ultrapure water reverse osmosis systems typically involves _______.
a) acid treatment
b) caustic treatment
c) sanitizing agent treatment
d) all of the above

8. Chlorine, as in household bleach, should never be used to sanitize reverse osmosis systems or water softeners because chlorine destroys membranes and resins.
a) True
b) False

9. Multimedia filters may be soaked overnight with chlorine solutions of 1,000 to 2,000 ppm.
a) True
b) False

10. The approximate amount of 5.25 percent household bleach necessary to produce 100 ppm of chlorine residual in one gallon of clear water is _______.
a) 1 cup
b) 1.5 cups
c) 1.5 teaspoonfuls
d) 1.5 tablespoonfuls