TEST YOUR KNOWLEDGE

Interpreting Water Analyses
Training Level: Advanced

To test your proficiency on the topics covered in this seminar, 20 questions are provided. The questions cover the major concepts participants learn in this seminar.

Contaminants

1. The purpose of expressing concentrations of potassium and chloride “as CaCO₃” on a water analysis report is:

a. To calculate Ca scaling potential
b. To calculate CO₃ scaling potential
c. To calculate CaCO₃ scaling potential
d. To calculate potassium chloride scaling potential
e. a., & b.
f. a., b. & c.
g. All (a. – d.)
h. None of the above

2. The purpose of expressing concentrations of potassium and chloride “as meq/L” on a water analysis report is:

a. To determine the precise concentration of potassium
b. To determine the precise concentration of chloride
c. To determine the precise concentration of potassium chloride
d. To calculate potassium chloride scaling potential
e. a., & b.
f. a., b. & c.
g. All (a. – d.)
h. None of the above

3. What CO₂-related compounds are in a sample that has measurable alkalinity and a pH of 7?

a. Carbonic acid
b. Bicarbonate ion
c. Carbonate ion
d. Hydroxide ion
e. a., & b.
f. a., b. & c.
g. All (a. – d.)
h. None of the above

4. The continuous addition of sodium hydroxide to a water sample will cause the pH of the solution to:

a. Stay the same for a while then rise linearly
b. Continuously rise linearly
c. Stay the same for a while then rise logarithmically
d. Continuously rise logarithmically
e. Stay the same for a while then drop linearly
f. Continuously drop linearly
g. Stay the same for a while then drop logarithmically
h. Continuously drop logarithmically

5. The addition of a large amount of table sugar to a tap water sample will cause the conductivity of the solution to:

a. Stay the same
b. Increase
c. Decrease
d. None of the above

Evaluating Scaling Potentials

6. Based on the following water analysis and a 75% recovery RO unit, we would be concerned about which of the following compounds and want to calculate the scaling potential(s):

Cations		Anions		Other
Name	mg/L	Name	mg/L	Name
Barium	0.01	Bicarbonate	51	Alkalinity, Total (mg/L as CaCO3)	42
Calcium	248	Chloride	328	Alkalinity, Bicarbonate (mg/L as CaCO3)	42
Iron	0.1	Fluoride	1.3	Alkalinity, Carbonate (mg/L as CaCO3)	0
Magnesium	115	Nitrate	1.1	Total Organic Carbon (mg/L)	3.2
Manganese	0.1	Phosphate	0.4	Carbon Dioxide (mg/L)	104
Potassium	7.3	Sulfate	855	Total Hardness, (mg/L as CaCO3)	1,126
Sodium	166	All others	0	Silica (mg/L)	22
Strontium	28			pH, units	7.0
All Others	0			Temperature, oF (oC)	80 (25)

a. Calcium chloride
b. Magnesium chloride
c. Sodium chloride
d. Sodium sulfate
e. Barium sulfate
f. a., b. & c.
g. All (a. – e.)
h. None of the above

7. Based on the following water analysis and a 45% recovery RO unit, we would be concerned about which of the following compounds and want to calculate the scaling potential(s):

Cations		Anions		Other
Name	mg/L	Name	mg/L	Name
Calcium	500	Bicarbonate	150	Total Organic Carbon (mg/L)	8.5
Magnesium	1,600	Chloride	23,000	Silica (mg/L)	1.4
Potassium	550	Nitrate	<0.01	pH, units	7.5
Sodium	13,000	Sulfate	2,500	Temperature, oF (oC)	84 (29)
All Others	0	All others	0

a. Magnesium chloride
b. Sodium chloride
c. Calcium carbonate
d. Calcium sulfate
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above

8. Based on the following water analysis and an 85% recovery RO unit, we would be concerned about which of the following compounds and want to calculate the scaling potential(s):

Cations		Anions		Other
Name	mg/L	Name	mg/L	Name
Calcium	5	Bicarbonate	34	Total Organic Carbon (mg/L)	16
Magnesium	2	Chloride	18	Silica (mg/L)	12
Potassium	0.2	Sulfate	15	pH, units	7.9
Sodium	20	All others	0	Temperature, oF (oC)	95 (35)
All Others	0

a. Magnesium chloride
b. Sodium chloride
c. Calcium carbonate
d. Calcium sulfate
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above

9. Based on the following water analysis and a 75% recovery RO unit, we would be concerned about which of the following compounds and want to calculate the scaling potential(s):

Cations		Anions		Other
Name	mg/L	Name	mg/L	Name	mg/L
Calcium	13	Bicarbonate	90	Total Organic Carbon (mg/L)	0.9
Magnesium	4	Chloride	4	Silica (mg/L)	80
Potassium	2	Sulfate	3	pH, units	8.0
Sodium	14	All others	0	Temperature, oF (oC)	61 (16)
All Others	0

a. Calcium bicarbonate
b. Sodium bicarbonate
c. Calcium carbonate
d. Silica
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above

10. Figure 1. Which solution (A or B) has a greater scaling potential and why?

Figure 1

a. A, because it has a lower TDS
b. B, because it has a higher TDS
c. B, because it has more Na and Cl present
d. Both b. and c. are correct
e. Both A and B have the same scaling potential
f. None of the above is correct

Evaluating Fouling Potentials

11. Based on the following water analysis and a 75% recovery RO unit, we would be concerned about which of the following compounds and want to calculate the fouling potential(s):

a. Calcium
b. Magnesium
c. Iron
d. Manganese
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above

12. Based on the following water analysis and a 45% recovery RO unit, we would be concerned about which of the following parameters and want to determine the fouling potential(s):

a. Calcium
b. Magnesium
c. Potassium
d. Sodium
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above

13. The SDI of the feed water to an RO unit is typically around 6. This means that:

a. The fouling potential of the feed water is acceptable
b. The SDI meets manufacturers’ specifications
c. The fouling potential of the feed water is unacceptable
d. There are too many silt particles present in the feed water
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above

14. The SDI of the feed water to an RO unit is measured at 0.1. This means that:

a. There must be MF pretreatment upstream of the sampling point
b. There must be UF pretreatment upstream of the sampling point
c. The fouling potential of the feed water is unacceptable
d. There are too many silt particles present in the feed water
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above

15. A well water has 0.1 mg/L of manganese (Mn⁺²), 3 mg/L of hydrogen sulfide (H₂S), 0.7 mg/L of iron (Fe⁺²), 100 mg/L of dissolved carbon dioxide (CO₂) and 5 mg/L of dissolved oxygen (O₂). What is the most glaring problem with this feed water analysis?

a. Concentration of Manganese
b. Concentration of Hydrogen Sulfide
c. Concentration of Iron
d. Concentration of Carbon Dioxide
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above

Evaluating Biofouling Potentials

16. Based on the following water analysis and a 75% recovery RO unit, we would be concerned about which of the following and want to calculate the biofouling potential:

a. TOC
b. Temperature
c. Phosphate
d. Nitrate
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above

17. Based on the following water analysis and a 45% recovery RO unit, we would be concerned about which of the following parameters and want to determine the biofouling potential:

a. TOC
b. Temperature
c. Sodium
d. Chloride
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above

18. Which of the following temperatures is the most ideal for most waterborne bacteria, allowing them to grow at their fastest rate?

a. 50-68°F (10-20°C)
b. 68-86°F (20-30°C)
c. 86-104°F (30-40°C)
d. 104-122°F (40-50°C)
e. 122-140°F (50-60°C)
f. 140-158°F (60-70°C)
g. 158-176°F (70-80°C)
h. None of the above

19. Relatively high values of which of the following is(are) the most ideal for most waterborne bacteria, allowing them to grow at their fastest rate?

a. BOD
b. COD
c. VOC
d. AOC
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above

20. A Heterotrophic Plate Count is performed on the feed water, permeate and concentrate of a 75% recovery RO unit at startup and again after it has been operating for 6 months.

This RO unit:

a. This RO unit is definitely biofouled
b. The pretreatment system is definitely biofouled
c. This RO unit is definitely not biofouled
d. The pretreatment system is definitely not biofouled
e. a. & b.
f. c. & d.
g. All (a. – d.)
h. None of the above