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

1. The interstices within a reverse osmosis membrane are how many times smaller than the diameter of a human hair?
a) 100
b) 1,000
c) 100,000
d) 1,000,000

2. Reverse osmosis membranes have physical holes that filter contaminants the same as other water filters.
a) True
b) False

3. Ions dissolved in water exist as single, discrete entities.
a) True
b) False

4. Some ions are rejected by RO membranes better than others.
a) True
b) False

5. Which type of membrane fouls faster?
a) Ultrafiltration (UF)
b) Reverse osmosis (RO)

6 & 7. The rate of water passage through an RO membrane is a function of (6) (a or b) and the rate of salt passage through an RO membrane is a function of (7) (a or b).
a) the difference in salt (solute) concentrations between the feed side and the permeate side of the membrane
b) the difference between the water pressures on each side of the membrane

8. SDI is a measure of membrane fouling rate caused by:
a) iron
b) phosphates
c) sulfates
d) suspended solids

9. Zeta potential measures:
a) turbidity in water
b) coagulant concentration in water
c) electrical charge of suspended particles in water
d) floc formation in water

10. Expressing water constituent concentrations as calcium carbonate (CaCO3) equivalents gives:
a) a relative concentration of charged molecules
b) the charge potential of an ion for reacting with other ions
c) the relative number of charged ions in solutions
d) working concentrations based on the number of molecules
e) all of the above