Wastewater Exam Class C (2025)
comprehensive questions and verified
detailed solutions
C. Is an Aerobic biological process - 📌- The Activated Sludge Process:
A. requires preaeration
B. requires Activated Carbon
C. is an aerobic biological process.
D. Usually precedes primary sedimentation.
E. Requires 50% by volume old sludge to work effectively.
D. Increase the F/M Ratio by Wasting More - 📌 - A complete mix activated
sludge plant has a fast settling sludge and high amounts of pin floc leaving the
clarifier. One way to correct this problem is to :
A. Increase the RAS Flow
B. Reduce Wasting Rates
C. Increase dissolved oxygen levels.
D. Increase the F/M ratio by wasting more
E. Increase the sludge age by wasting less.
E. all the above -📌 - Which of the following flow rates should be measured if the
operator is to control plant properly?
A. Aeration rate or resulting dissolved oxygen level.
B. Influent or effluent.
C. return sludge
D. waste sludge
E. all the above
C. Seeding the process with sufficient good quality sludge - 📌
- During start up
your aeration tank produces excessive amounts of billowing white foam. This can
be corrected by:
A. Doing nothing, it will go away in a few hours
B. Increasing the sludge wasting rate
C. Seeding the process with sufficient good quality sludge
D. Spraying water on the foam until it is gone
E. Taking a weeks vacation
📌
A. there is almost always a good technical solution. It may require considerable
experience and time to learn whaat it is. - - In solving an operational problem
, C. don't let the laboratory personnel influence you're judgement as to what the
best solution is.
D. standard textbooks in sanitary engineering are the best source of information.
E. It is best to do nothing until the TNRCCC sends a violation notice.
E. B and D - 📌- When the return sludge rate is too low, what happens?
A. the aeration tank will not fill
B. There will be insufficient organisms to treat the wast load entering the aeration
basin
C. the activated sludge in the aerator will starve.
D. the sludge blanket in the secondary clarifier could become too high.
E. B and D
E. All of the above - 📌 - What factors affect how well the mixed liquor suspended
solids settle in the final clarifier?
A. flow velocity and or turbulence
B. temperature
C. quality of the mixed liquor solids
D. Short circuiting
E. All of the above
E. All the above except C. - 📌 - The Active sludge process parameters which n
operator can change directly are:
A. aeration rates.
B. waste rates.
C. the ratio of free swimming to stalked ciliates.
D. Return sludge rates.
E. All the above except C.
B. increase dissolved oxygen levels and increase the sludge age - 📌 - Which of
the following would you use to increase the degree of nitrification in an activated
sludge plant?
A. increase the wast rates
B. increase dissolved oxygen levels and increase the sludge age
C. Remove excess alkalinity from the wastewater
D. Maintain a thicker sludge blanket n the clarifier
E. Inhibit the growth of the nitrifying bacteria with chemicals.
A. 10- 20 % per day - 📌- The Maximum change in the sludge wasting rates to
maintain uniform operating conditions should be about
comprehensive questions and verified
detailed solutions
C. Is an Aerobic biological process - 📌- The Activated Sludge Process:
A. requires preaeration
B. requires Activated Carbon
C. is an aerobic biological process.
D. Usually precedes primary sedimentation.
E. Requires 50% by volume old sludge to work effectively.
D. Increase the F/M Ratio by Wasting More - 📌 - A complete mix activated
sludge plant has a fast settling sludge and high amounts of pin floc leaving the
clarifier. One way to correct this problem is to :
A. Increase the RAS Flow
B. Reduce Wasting Rates
C. Increase dissolved oxygen levels.
D. Increase the F/M ratio by wasting more
E. Increase the sludge age by wasting less.
E. all the above -📌 - Which of the following flow rates should be measured if the
operator is to control plant properly?
A. Aeration rate or resulting dissolved oxygen level.
B. Influent or effluent.
C. return sludge
D. waste sludge
E. all the above
C. Seeding the process with sufficient good quality sludge - 📌
- During start up
your aeration tank produces excessive amounts of billowing white foam. This can
be corrected by:
A. Doing nothing, it will go away in a few hours
B. Increasing the sludge wasting rate
C. Seeding the process with sufficient good quality sludge
D. Spraying water on the foam until it is gone
E. Taking a weeks vacation
📌
A. there is almost always a good technical solution. It may require considerable
experience and time to learn whaat it is. - - In solving an operational problem
, C. don't let the laboratory personnel influence you're judgement as to what the
best solution is.
D. standard textbooks in sanitary engineering are the best source of information.
E. It is best to do nothing until the TNRCCC sends a violation notice.
E. B and D - 📌- When the return sludge rate is too low, what happens?
A. the aeration tank will not fill
B. There will be insufficient organisms to treat the wast load entering the aeration
basin
C. the activated sludge in the aerator will starve.
D. the sludge blanket in the secondary clarifier could become too high.
E. B and D
E. All of the above - 📌 - What factors affect how well the mixed liquor suspended
solids settle in the final clarifier?
A. flow velocity and or turbulence
B. temperature
C. quality of the mixed liquor solids
D. Short circuiting
E. All of the above
E. All the above except C. - 📌 - The Active sludge process parameters which n
operator can change directly are:
A. aeration rates.
B. waste rates.
C. the ratio of free swimming to stalked ciliates.
D. Return sludge rates.
E. All the above except C.
B. increase dissolved oxygen levels and increase the sludge age - 📌 - Which of
the following would you use to increase the degree of nitrification in an activated
sludge plant?
A. increase the wast rates
B. increase dissolved oxygen levels and increase the sludge age
C. Remove excess alkalinity from the wastewater
D. Maintain a thicker sludge blanket n the clarifier
E. Inhibit the growth of the nitrifying bacteria with chemicals.
A. 10- 20 % per day - 📌- The Maximum change in the sludge wasting rates to
maintain uniform operating conditions should be about
