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. Which water treatment chemical must be manufactured on-site for immediate use because it is highly reactive and quickly decomposes?
a) chlorine
b) activated carbon
c) potassium permanganate
d) ozone

2. The time for half of the ozone in water to decompose (half-life) is:
a) 4 to 12 hours
b) 3 to 20 minutes
c) 30 to 60 seconds

3. The decomposition of ozone in water will be most rapid when the water temperature is:
a) less than 40°F (4.4°C)
b) between 50°F (10°C) and 60°F (15.6°C)
c) greater than 80°F (26.7°C)
d) over minus 60°F (minus 51.1°C) dew point

4. Ozonation treatment of water can provide:
a) disinfection
b) clearer water
c) better particle aggregation
d) all of the above

5. Ozone can corrode or damage:
a) metals
b) plastics
c) rubber
d) all of the above

6. Suitable materials for continuous exposure to an ozone/water mixture include:
a) polyvinyl chloride (PVC)
b) polyethylene
c) polybutylene
d) hard copper pipe
e) none of the above

7. Suitable materials for continuous exposure to ozone/air mixtures include:
a) Teflon
b) stainless steel
c) PVC
d) all of the above

8. An important parameter(s) of ozone generation is (are):
a) ozone production
b) ozone concentration
c) both of the above
d) none of the above

9. Ozone can be generated via:
a) corona discharge
b) ultraviolet light
c) a high-voltage electrical supply
d) a and b
e) all of the above

10. What is the ozone concentration produced by an ozone generator that delivers one pound of ozone per day with an air flow through the generator of 0.9 standard cubic feet per minute (scfm) of dry air? [Given: At standard conditions of 20°C (68°F) and 14.7 psi, dry air weighs 1.2 grams per liter or 0.075 pounds per standard cubic foot (scf).]
a) 0.1%
b) 1%
c) 2%
d) 3%