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CWEA Wastewater Laboratory Technician Exam
Practice Questions And Correct Answers||Verified
Exam!!!|| (Verified Answers) Plus Rationale 2026/2027
Q&A| Instant Download Pdf
What is the Argentometric method? - Answer-Titration of
the sample with a standard solution of silver nitrate
(AgNO3) - Indicator: Chromate ions (CrO4) - End point:
reddish silver chromate
What is the Mercuric Nitrate method? - Answer-Titration
with standard mercuric nitrate solution -pH must be
adjusted between 2.3 and 2.8 - Indicator: Diphenyl
carbazone - End point: Change from blue to purple in the
presence of mercury
Which of the following can be an Interference of the
Mercuric Nitrate Method? - Answer-Sulfide, bromide,
orthophosphate (over 30 ppm), and iodide
Why does the color change in water?
a. Presence of decaying vegetable matter
b. metal ions (ie. iron)
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c. industrial and domestic pollution
d. All of the above - Answer-d
How is color measured - Answer-Measured using visual
comparison method
What is the visual comparison method - Answer-Sample
compared to standards using matching nessler tubes -
Standards prepared with solution containing
chloroplatinate and cobaltous chlorid
What is the standard unit for color? - Answer-One unit=
color resulting from 1 mg of platinum/L
What is 2-color reporting? - Answer-True and Apparent
Define True color - Answer-Color from suspended solids,
determine using sample treated to remove turbidity
What is Apparent Color? - Answer-Color from both
dissolved and suspended solids
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What is Conductivity? - Answer-H2O capability to pass
electrical flow
What is the conductivity of pure water? - Answer-0
What are the Units of conductivity? - Answer-µS/cm
(micromhos/cm)
What Temperature should conductivity be read at? -
Answer-25 degrees Celcius
How is conductivity affected? - Answer-Mobility of ions,
conductivity is dependent on viscosity
What is Viscosity? - Answer-the resistance of a liquid to
flow
Describe the relationship of temperature and viscosity? -
Answer-Inverse
What is an Acid? - Answer-A compound that liberates
hydrogen ions and has a pH below 7.
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What is Alkalinity? - Answer-The measurement of a
sample's capacity to neutralize acid.
What does Alkalinity measure? - Answer-The carbonate,
bicarbonate, and hydroxide ion concentration found in
water
What is the primary reason for measuring alkalinity? -
Answer-Used in control of many water and wastewater
unit processes
What is chloride? - Answer-Major anion found in many
natural waters - Can impart salty taste in H2O
What increases the concentration of chloride in
wastewater? - Answer-Chloride in human diet and
softeners flushed into sanitary sewer system
2 most prevalent methods of measuring chloride? -
Answer-argentometric and mercuric nitrate
CWEA Wastewater Laboratory Technician Exam
Practice Questions And Correct Answers||Verified
Exam!!!|| (Verified Answers) Plus Rationale 2026/2027
Q&A| Instant Download Pdf
What is the Argentometric method? - Answer-Titration of
the sample with a standard solution of silver nitrate
(AgNO3) - Indicator: Chromate ions (CrO4) - End point:
reddish silver chromate
What is the Mercuric Nitrate method? - Answer-Titration
with standard mercuric nitrate solution -pH must be
adjusted between 2.3 and 2.8 - Indicator: Diphenyl
carbazone - End point: Change from blue to purple in the
presence of mercury
Which of the following can be an Interference of the
Mercuric Nitrate Method? - Answer-Sulfide, bromide,
orthophosphate (over 30 ppm), and iodide
Why does the color change in water?
a. Presence of decaying vegetable matter
b. metal ions (ie. iron)
,2|Page
c. industrial and domestic pollution
d. All of the above - Answer-d
How is color measured - Answer-Measured using visual
comparison method
What is the visual comparison method - Answer-Sample
compared to standards using matching nessler tubes -
Standards prepared with solution containing
chloroplatinate and cobaltous chlorid
What is the standard unit for color? - Answer-One unit=
color resulting from 1 mg of platinum/L
What is 2-color reporting? - Answer-True and Apparent
Define True color - Answer-Color from suspended solids,
determine using sample treated to remove turbidity
What is Apparent Color? - Answer-Color from both
dissolved and suspended solids
,3|Page
What is Conductivity? - Answer-H2O capability to pass
electrical flow
What is the conductivity of pure water? - Answer-0
What are the Units of conductivity? - Answer-µS/cm
(micromhos/cm)
What Temperature should conductivity be read at? -
Answer-25 degrees Celcius
How is conductivity affected? - Answer-Mobility of ions,
conductivity is dependent on viscosity
What is Viscosity? - Answer-the resistance of a liquid to
flow
Describe the relationship of temperature and viscosity? -
Answer-Inverse
What is an Acid? - Answer-A compound that liberates
hydrogen ions and has a pH below 7.
, 4|Page
What is Alkalinity? - Answer-The measurement of a
sample's capacity to neutralize acid.
What does Alkalinity measure? - Answer-The carbonate,
bicarbonate, and hydroxide ion concentration found in
water
What is the primary reason for measuring alkalinity? -
Answer-Used in control of many water and wastewater
unit processes
What is chloride? - Answer-Major anion found in many
natural waters - Can impart salty taste in H2O
What increases the concentration of chloride in
wastewater? - Answer-Chloride in human diet and
softeners flushed into sanitary sewer system
2 most prevalent methods of measuring chloride? -
Answer-argentometric and mercuric nitrate
