WASTEWATER TEST PRACTICE
EXAMINATION 2026 QUESTIONS WITH
ANSWERS GRADED A+
◍ Why is mixing important in an anaerobic digester?A) Increases the build up
of gritB) Speeds up digestion rateC) Achieves heterogeneous content in the
digesterD) Forms a scum blanket.
Answer: B) Speeds up digestion rate (v.2 pg 176)
◍ What is the color of a pond that is operating properly?A) BrownB) Deep
green colorC) ClearD) Tan.
Answer: B) Deep green color (v.1 pg 309)
◍ What is the breakdown of nitrate to nitrogen gas called?
A. Nitrification
B. Denitrification
C. Autotriphication
D. Anaerobic decomposition.
Answer: B. Denitrification
◍ Why would you chlorinate the RAS line?
A. Remove struvite
B. Lower the pH of incoming
C. Control Filamentous bacteria
D. Meet chlorine demand.
Answer: C. Control Filamentous bacteria
◍ What is the typical removal efficiency from bacteria in a primary
clarifier?A) 0-5%B) 25-75%C) 5-10%D) 10-20%.
Answer: B) 25-75% (v.1 pg 129)
◍ What could cause short circuiting in a clarifier?A) Sludge composition B)
, Reduction in flowrateC) Uneven weir settingsD) Broken sludge pump.
Answer: C) Uneven weir settings (v.1 pg 125)
◍ What is a chloramine? A) Free chlorineB) A chemical that is formed when
chlorine reacts with ironC) Combined chlorine- a chemical that is formed
when chlorine reacts with ammoniaD) A chemical that is formed when
chlorine reacts with air..
Answer: C) Combined chlorine- a chemical that is formed when chlorine
reacts with ammonia (v.1 pg 350)
◍ What can happen if more than 40 Ibs of chlorine is withdrawn from a 150 Ib
tank in a 24 hr period?
A. Reliquification
B. Increased pressure
C. Freezing of the lines
D. Budget increase.
Answer: C. Freezing of the lines
◍ Which law regulates wastewater discharge to receiving water?A)
Wastewater ActB) Clean Water ActC) National Discharge ActD) Federal
Effluent Act.
Answer: B) Clean Water Act
◍ What is a vulnerability assessment?A) Assesses the impact of hydrogen
sulfide to a concrete structureB) Analyzes the impact of flow and infiltration
problem to the plant hydraulicsC) Estimates the vulnerability of aquatic
wildlife to excessive algae growthD) Contingency planning to determine the
vulnerability of the utility during various types of emergencies and identify
corrective actions to reduce the risks.
Answer: D) Contingency planning to determine the vulnerability of the
utility during various types of emergencies and identify corrective actions to
reduce the risks (v.2 pg 722)
◍ What the two main gasses produced b an anaerobic digester?
A. Methane & Carbon Monoxide
B. Co2 & CH3
, C. Methane & Co2
D. Hydrogen Sulfide & Oxygen.
Answer: C. Methane & Co2
◍ What type of sludge would you expect in an aeration tank if the content is
dark and has low DO?A) Sludge that is heavyB) Chlorinated SludgeC)
Septic SludgeD) Healthy Sludge.
Answer: C) Septic Sludge (v.2 pg 75)
◍ What is a major cause of repeated sludge bulk?A) High pHB) High DOC)
High food to mircoorganism loading ratesD) High nutrient concentration.
Answer: C) High food to mircoorganism loading rates (v.2 pg 71)
◍ What are commonly used to control chlorine feed rate for disinfection?A)
BOD and MLVSSB) pH and temperatureC) Flow and chlorine residual D)
DO and TSS.
Answer: C) Flow and chlorine residual (v.1 pg 356)
◍ What do you do if you experience a plant upset due to a hydraulic overload?
A. Decrease DO
B. Increase RAS
C. Increase WAR
D. Decrease WAS to maintain microorganisms population.
Answer: D. Decrease WAS to maintain microorganisms popultion
◍ One to two percent of the digester gas in an anaerobic consists of A)
Hydrogen, Nitrogen, Hydrogen sulfide, and other gasesB) MethaneC)
Carbon DioxideD) CH_4.
Answer: A) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases (v.2 pg
158)
◍ What is the typical detention time for a primary clarifier?A) 3 to 4 hoursB)
30 minutesC) 6 hoursD) 1.5 to 2 hours.
Answer: D) 1.5 to 2 hours (v.1 pg 43)
◍ What could cause the slime growth on a rotating biological contactor to
appear black?A) It could indicate solids or organic overloading B) High DO
, in the plant effluentC) Lack of BOD in the influent to the rotating biological
contactorD) Low hydraulic loading.
Answer: A) It could indicate solids or organic overloading (v.1 pg 228)
◍ What should you do if there is a thick, dark foam on the surface of an
aeration tank?A) Increase the sludge wastingB) Decrease sludge wastingC)
Maintain current MLSS concentration D) Increase the mircoorganism
population.
Answer: A) Increase the sludge wasting (v.2 pg 53)
◍ What should you do if your samples come to the lab and have settled to the
bottom?
A. Discard
B. Mix them well
C. Re-Sample
D. Run tests.
Answer: B. Mix them well
◍ What is the funnel called that is used along with the vacuum apparatus when
doing solids testing?
A. Buchner funnel
B. Filter funnel
C. Micro funnel
D. Straining funnel.
Answer: A. Buchner funnel
◍ What should be done if the SVI is high and there is an excess of normal
filamentous microorganisms in the activated sludge process?A) Inject
hydrogen peroxide in the secondary effluentB) Make sure DO levels is very
low in the aeration tankC) Decrease MLSS and sludge ageD) Chlorinate the
return activated sludge.
Answer: D) Chlorinate the return activated sludge (v.2 pg 60)
◍ What is a MSDS?A) A federal law that is designed to protect the health and
safety of workersB) A condition in which a persons nose is no longer able to
detect odor from a chemicalC) A document that contains important
EXAMINATION 2026 QUESTIONS WITH
ANSWERS GRADED A+
◍ Why is mixing important in an anaerobic digester?A) Increases the build up
of gritB) Speeds up digestion rateC) Achieves heterogeneous content in the
digesterD) Forms a scum blanket.
Answer: B) Speeds up digestion rate (v.2 pg 176)
◍ What is the color of a pond that is operating properly?A) BrownB) Deep
green colorC) ClearD) Tan.
Answer: B) Deep green color (v.1 pg 309)
◍ What is the breakdown of nitrate to nitrogen gas called?
A. Nitrification
B. Denitrification
C. Autotriphication
D. Anaerobic decomposition.
Answer: B. Denitrification
◍ Why would you chlorinate the RAS line?
A. Remove struvite
B. Lower the pH of incoming
C. Control Filamentous bacteria
D. Meet chlorine demand.
Answer: C. Control Filamentous bacteria
◍ What is the typical removal efficiency from bacteria in a primary
clarifier?A) 0-5%B) 25-75%C) 5-10%D) 10-20%.
Answer: B) 25-75% (v.1 pg 129)
◍ What could cause short circuiting in a clarifier?A) Sludge composition B)
, Reduction in flowrateC) Uneven weir settingsD) Broken sludge pump.
Answer: C) Uneven weir settings (v.1 pg 125)
◍ What is a chloramine? A) Free chlorineB) A chemical that is formed when
chlorine reacts with ironC) Combined chlorine- a chemical that is formed
when chlorine reacts with ammoniaD) A chemical that is formed when
chlorine reacts with air..
Answer: C) Combined chlorine- a chemical that is formed when chlorine
reacts with ammonia (v.1 pg 350)
◍ What can happen if more than 40 Ibs of chlorine is withdrawn from a 150 Ib
tank in a 24 hr period?
A. Reliquification
B. Increased pressure
C. Freezing of the lines
D. Budget increase.
Answer: C. Freezing of the lines
◍ Which law regulates wastewater discharge to receiving water?A)
Wastewater ActB) Clean Water ActC) National Discharge ActD) Federal
Effluent Act.
Answer: B) Clean Water Act
◍ What is a vulnerability assessment?A) Assesses the impact of hydrogen
sulfide to a concrete structureB) Analyzes the impact of flow and infiltration
problem to the plant hydraulicsC) Estimates the vulnerability of aquatic
wildlife to excessive algae growthD) Contingency planning to determine the
vulnerability of the utility during various types of emergencies and identify
corrective actions to reduce the risks.
Answer: D) Contingency planning to determine the vulnerability of the
utility during various types of emergencies and identify corrective actions to
reduce the risks (v.2 pg 722)
◍ What the two main gasses produced b an anaerobic digester?
A. Methane & Carbon Monoxide
B. Co2 & CH3
, C. Methane & Co2
D. Hydrogen Sulfide & Oxygen.
Answer: C. Methane & Co2
◍ What type of sludge would you expect in an aeration tank if the content is
dark and has low DO?A) Sludge that is heavyB) Chlorinated SludgeC)
Septic SludgeD) Healthy Sludge.
Answer: C) Septic Sludge (v.2 pg 75)
◍ What is a major cause of repeated sludge bulk?A) High pHB) High DOC)
High food to mircoorganism loading ratesD) High nutrient concentration.
Answer: C) High food to mircoorganism loading rates (v.2 pg 71)
◍ What are commonly used to control chlorine feed rate for disinfection?A)
BOD and MLVSSB) pH and temperatureC) Flow and chlorine residual D)
DO and TSS.
Answer: C) Flow and chlorine residual (v.1 pg 356)
◍ What do you do if you experience a plant upset due to a hydraulic overload?
A. Decrease DO
B. Increase RAS
C. Increase WAR
D. Decrease WAS to maintain microorganisms population.
Answer: D. Decrease WAS to maintain microorganisms popultion
◍ One to two percent of the digester gas in an anaerobic consists of A)
Hydrogen, Nitrogen, Hydrogen sulfide, and other gasesB) MethaneC)
Carbon DioxideD) CH_4.
Answer: A) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases (v.2 pg
158)
◍ What is the typical detention time for a primary clarifier?A) 3 to 4 hoursB)
30 minutesC) 6 hoursD) 1.5 to 2 hours.
Answer: D) 1.5 to 2 hours (v.1 pg 43)
◍ What could cause the slime growth on a rotating biological contactor to
appear black?A) It could indicate solids or organic overloading B) High DO
, in the plant effluentC) Lack of BOD in the influent to the rotating biological
contactorD) Low hydraulic loading.
Answer: A) It could indicate solids or organic overloading (v.1 pg 228)
◍ What should you do if there is a thick, dark foam on the surface of an
aeration tank?A) Increase the sludge wastingB) Decrease sludge wastingC)
Maintain current MLSS concentration D) Increase the mircoorganism
population.
Answer: A) Increase the sludge wasting (v.2 pg 53)
◍ What should you do if your samples come to the lab and have settled to the
bottom?
A. Discard
B. Mix them well
C. Re-Sample
D. Run tests.
Answer: B. Mix them well
◍ What is the funnel called that is used along with the vacuum apparatus when
doing solids testing?
A. Buchner funnel
B. Filter funnel
C. Micro funnel
D. Straining funnel.
Answer: A. Buchner funnel
◍ What should be done if the SVI is high and there is an excess of normal
filamentous microorganisms in the activated sludge process?A) Inject
hydrogen peroxide in the secondary effluentB) Make sure DO levels is very
low in the aeration tankC) Decrease MLSS and sludge ageD) Chlorinate the
return activated sludge.
Answer: D) Chlorinate the return activated sludge (v.2 pg 60)
◍ What is a MSDS?A) A federal law that is designed to protect the health and
safety of workersB) A condition in which a persons nose is no longer able to
detect odor from a chemicalC) A document that contains important
