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. Silica in water:
      a) precipitates as the anionic portion of a salt
      b) polymerizes to form colloidal silica
      c) is easy to redissolve once it falls out of solution
      d) a and b
      e) a, b and c

2. A recommended concentration of silica in feedwater to a reverse osmosis system is:
      a) 0.2 mg/L or less
      b) 2 mg/L or less
      c) 20 mg/L or less
      d) 200 mg/L or less

3. Sulfides are most frequently found in the shallow wells of this state:
      a) Maine
      b) Florida
      c) Arizona
      d) Washington

4. Hydrogen sulfide can be removed from water by:
      a) chlorination and media filtration
      b) water softener
      c) BIRM filter
      d) all of the above

5. Phosphates fed in municipal water supplies to sequester iron generally help prevent fouling by precipitation in RO concentrate streams.
      a) True
      b) False

6. The reverse osmosis membrane least likely to attract charged foulants to its surface is the:
      a) cellulose acetate membrane
      b) polyamide/thin film membrane
      c) charged polysulfone membrane

7. Membrane hydrolysis:
      a) occurs most in polyamide/thin film membranes
      b) is caused by oxidants like chlorine in water
      c) improves salt rejection as water combines with the membrane
      d) occurs most rapidly at about pH 4.8
      e) all of the above
      f) none of the above

8. Better performance on sea water desalination will be obtained with:
      a) cellulose acetate membranes
      b) polyamide/thin film membranes

9. Polyamide membranes:
      a) use a thicker polyamide membrane layer for sea water desalination applications
      b) can be cleaned with cationic surfactants
      c) can reduce fouling from biological activity by chlorine or iodine injections to the feedwater
      d) all of the above
      e) none of the above

10. Charged polysulfone reverse osmosis membranes:
      a) contain physical pores large enough to pass salts
      b) are chemically sulfonated similar to the process that gives cation exchange resins their charge characteristics
      c) offer chlorine as well as pH tolerances
      d) require water softening to remove divalent and trivalent cations in the feed stream
      e) all of the above
      f) none of the above


To view the answers to these and other Certification Action Line questions, click here.