WASTEWATER GRADE 1EXAM
QUESTIONS WITH DETAILED ANSWERS
2026
What is the methane content in a properly operating anaerobic digester? -
ANSWERS65 to 70% by volume
What will the addition of chlorine gas do to the pH of wastewater? -
ANSWERSDecrease the pH
What is the purpose of a Parshall flume? - ANSWERSMeasure Flowrate
What is the typical removal efficiency of settable solids in a primary clarifier? -
ANSWERS95 to 99%
Pumping scum from a primary clarifier can cause more piping problems than other
substances pumped at a wastewater treatment plant? - ANSWERSTRUE.
What might cause thick billows of white sudsy foam in the aeration tank? -
ANSWERSMLSS is too low
What does the "M" in F/M ratio represent? - ANSWERSThe mixed liquor volatile
suspended solids in the aeration tank.
In general, how will warmer temperature affect the settling rate of solids in a clarifier? -
ANSWERSIt increases the settling rate
What could happen if the digester gas is mixed with air (85 to 95% by volume)? -
ANSWERSCause an explosion
How will algae impact the chlorine demand in the pond effluent? - ANSWERSIt increase
the chlorine demand
TRUE OR FALSE: A positive displacement pump must NEVER be started with the
discharge valve closed. - ANSWERSTRUE
TRUE OR FALSE: The volume of a secondary clarifier is not needed to determine the
F/M ratio? - ANSWERSTRUE
Which of the following is one of the basic rules of lab work?
a. Do not leave keys in equipment or vehicles at any time.
b. Patrol the facilities frequently, and look for suspicious activity or behavior.
, c. Never Pipet hazardous material with your mouth, even if the pipet has been sterilized.
d. Lock Out and Tag out relevant mechanical and electrical equipment before staring
any maintenance activity. - ANSWERSC
What is the recirculation ration for a trickling filter?
A. Qr/Q
B. Q/Qr
C. Q/Qr+Q
D.Qr+Q/Q - ANSWERSA
Which of the following is true about COD and BOD?
A. They are direct measurements of organic content in the influent.
B. They measure the inorganic content of the influent
C. They represent the amount of filamentous bacteria in the influent
D. They are indirect measurements of the organic content in the influent. - ANSWERSD
What is the purpose of the grit channel?
A. Remove dissolved and non-settable organics
B. Remove heavy inorganic wastes
C. To allow activated sludge to settle
D. Remove substances that float and readily settle from the wastewater as primary
treatment. - ANSWERSB
Which of the following is true about the extended aeration process?
A. Bugs get more food
B. Wasting is not necessary
C. It does not produce as much waste sludge as the other process
D. It is very different from the conventional activated sludge process. - ANSWERSC
What is the correct formula for solids in wastewater?
A. Non-volatile solids +Suspended solids = Total solids in the influent
B. Dissolved Solids + Settable Solids = Total Suspended Solids
C. Colloids + Dissolved Solids = Total Suspended Solids
D. Non-settable solids + Settable Solids = Total Suspended solids - ANSWERSD
What is "freeboard" in a waste stabilization pond?
A. Operational depth of a pond
B. Wooden inlet and outlet structures.
C. Wooden baffles
D. Vertical Distance from the normal water surface to the top of the levee. -
ANSWERSD
What is one of the requirements for the BOD test?
A. The BOD bottle should be completely filled to the top.
B. The BOD bottles must be 100-ml in size.
C. Samples should be incubated at 30 degrees Celsius.
QUESTIONS WITH DETAILED ANSWERS
2026
What is the methane content in a properly operating anaerobic digester? -
ANSWERS65 to 70% by volume
What will the addition of chlorine gas do to the pH of wastewater? -
ANSWERSDecrease the pH
What is the purpose of a Parshall flume? - ANSWERSMeasure Flowrate
What is the typical removal efficiency of settable solids in a primary clarifier? -
ANSWERS95 to 99%
Pumping scum from a primary clarifier can cause more piping problems than other
substances pumped at a wastewater treatment plant? - ANSWERSTRUE.
What might cause thick billows of white sudsy foam in the aeration tank? -
ANSWERSMLSS is too low
What does the "M" in F/M ratio represent? - ANSWERSThe mixed liquor volatile
suspended solids in the aeration tank.
In general, how will warmer temperature affect the settling rate of solids in a clarifier? -
ANSWERSIt increases the settling rate
What could happen if the digester gas is mixed with air (85 to 95% by volume)? -
ANSWERSCause an explosion
How will algae impact the chlorine demand in the pond effluent? - ANSWERSIt increase
the chlorine demand
TRUE OR FALSE: A positive displacement pump must NEVER be started with the
discharge valve closed. - ANSWERSTRUE
TRUE OR FALSE: The volume of a secondary clarifier is not needed to determine the
F/M ratio? - ANSWERSTRUE
Which of the following is one of the basic rules of lab work?
a. Do not leave keys in equipment or vehicles at any time.
b. Patrol the facilities frequently, and look for suspicious activity or behavior.
, c. Never Pipet hazardous material with your mouth, even if the pipet has been sterilized.
d. Lock Out and Tag out relevant mechanical and electrical equipment before staring
any maintenance activity. - ANSWERSC
What is the recirculation ration for a trickling filter?
A. Qr/Q
B. Q/Qr
C. Q/Qr+Q
D.Qr+Q/Q - ANSWERSA
Which of the following is true about COD and BOD?
A. They are direct measurements of organic content in the influent.
B. They measure the inorganic content of the influent
C. They represent the amount of filamentous bacteria in the influent
D. They are indirect measurements of the organic content in the influent. - ANSWERSD
What is the purpose of the grit channel?
A. Remove dissolved and non-settable organics
B. Remove heavy inorganic wastes
C. To allow activated sludge to settle
D. Remove substances that float and readily settle from the wastewater as primary
treatment. - ANSWERSB
Which of the following is true about the extended aeration process?
A. Bugs get more food
B. Wasting is not necessary
C. It does not produce as much waste sludge as the other process
D. It is very different from the conventional activated sludge process. - ANSWERSC
What is the correct formula for solids in wastewater?
A. Non-volatile solids +Suspended solids = Total solids in the influent
B. Dissolved Solids + Settable Solids = Total Suspended Solids
C. Colloids + Dissolved Solids = Total Suspended Solids
D. Non-settable solids + Settable Solids = Total Suspended solids - ANSWERSD
What is "freeboard" in a waste stabilization pond?
A. Operational depth of a pond
B. Wooden inlet and outlet structures.
C. Wooden baffles
D. Vertical Distance from the normal water surface to the top of the levee. -
ANSWERSD
What is one of the requirements for the BOD test?
A. The BOD bottle should be completely filled to the top.
B. The BOD bottles must be 100-ml in size.
C. Samples should be incubated at 30 degrees Celsius.
