CWEA – Advanced Water Treatment Exam Questions 1– 200 | 2025 Exam

CWEA – Advanced Water Treatment Exam
Questions 1– 200 | 2025 Exam



Question 1
Which of the following is most effective in removing dissolved salts from water?
A) Ultrafiltration
B) Reverse osmosis (answer)
C) Sand filtration
D) Microfiltration



Question 2
What is the purpose of adding antiscalant chemicals in reverse osmosis systems?
A) To disinfect membranes
B) To reduce scaling (answer)
C) To neutralize pH
D) To enhance coagulation



Question 3
Which disinfection method produces disinfection byproducts such as trihalomethanes?
A) UV disinfection
B) Chlorination (answer)
C) Ozonation
D) Membrane filtration



Question 4
The flux rate in a membrane system is typically expressed in which units?
A) Gallons per minute per foot
B) Gallons per square foot per day (answer)
C) Liters per hour
D) Meters per second



Question 5
What is the purpose of backwashing in granular media filters?
A) To remove hardness

,B) To clean accumulated solids (answer)
C) To disinfect the filter
D) To reduce pH



Question 6
Which advanced oxidation process uses UV light and hydrogen peroxide?
A) Fenton’s reaction
B) Photolysis
C) UV/H₂O₂ (answer)
D) Ozone alone



Question 7
Which membrane type has the smallest pore size?
A) Microfiltration
B) Ultrafiltration
C) Nanofiltration
D) Reverse osmosis (answer)



Question 8
What is the primary mechanism of virus removal in membrane filtration?
A) Adsorption
B) Size exclusion (answer)
C) Chemical oxidation
D) pH adjustment



Question 9
In a reverse osmosis system, permeate refers to:
A) The feedwater
B) The concentrated reject stream
C) The treated water that passes through the membrane (answer)
D) The brine stream



Question 10
Which of the following best describes the term “fouling”?
A) Biological growth only
B) Any accumulation reducing membrane performance (answer)

,C) Salt precipitation alone
D) pH imbalance



Question 11
What is the main purpose of cleaning-in-place (CIP) procedures?
A) To adjust temperature
B) To remove fouling deposits (answer)
C) To reduce pressure
D) To control pH



Question 12
Which disinfectant leaves no residual in treated water?
A) Chlorine
B) Chloramines
C) Ozone (answer)
D) Hypochlorite



Question 13
Which membrane process is most effective in softening water?
A) Ultrafiltration
B) Reverse osmosis (answer)
C) Microfiltration
D) Media filtration



Question 14
What parameter measures the tendency of particulate matter to foul membranes?
A) Conductivity
B) Silt density index (answer)
C) Turbidity alone
D) pH



Question 15
What does “transmembrane pressure” refer to?
A) Pressure difference across the feed tank
B) Pressure difference across the membrane surface (answer)

, C) Pressure in the brine line only
D) Atmospheric pressure



Question 16
Which parameter is used to assess disinfection performance in UV systems?
A) Turbidity reduction
B) UV dose (mJ/cm²) (answer)
C) Residual chlorine
D) Oxidation-reduction potential



Question 17
What is the purpose of using sodium bisulfite in water treatment?
A) pH adjustment
B) Dechlorination (answer)
C) Scale inhibition
D) Coagulation



Question 18
Which membrane process requires the highest operating pressure?
A) Microfiltration
B) Ultrafiltration
C) Nanofiltration
D) Reverse osmosis (answer)



Question 19
Which parameter indicates membrane integrity in ultrafiltration?
A) Pressure drop alone
B) Turbidity
C) Pressure decay test (answer)
D) Silt density index



Question 20
What is the purpose of blending permeate and bypass water?
A) To improve taste (answer)
B) To increase hardness