Wastewater Exam Class C

Wastewater Exam Class C

The Activated Sludge Process:

• requires preparation
• requires Activated Carbon
• is an aerobic biological process.
• Usually precedes primary sedimentation.
• Requires 50% by volume old sludge to work effectively.

(Ans- C. Is an Aerobic biological process

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 :

• Increase the RAS Flow
• Reduce Wasting Rates
• Increase dissolved oxygen levels.
• Increase the F/M ratio by wasting more
• Increase the sludge age by wasting less.

(Ans- D. Increase the F/M Ratio by Wasting More

Which of the following flow rates should be measured if the operator is to control plant properly?

• Aeration rate or resulting dissolved oxygen level.
• Influent or effluent.
• return sludge
• waste sludge
• all the above

(Ans- E. all the above

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During start up your aeration tank produces excessive amounts of billowing

white foam. This can be corrected by:

• Doing nothing, it will go away in a few hours
• Increasing the sludge wasting rate
• Seeding the process with sufficient good quality sludge
• Spraying water on the foam until it is gone
• Taking a weeks vacation

(Ans- C. Seeding the process with sufficient good quality sludge

In solving an operational problem at a treatment plant:

• there is almost always a good technical solution. It may require

considerable experience and time to learn what it is.

• Human errors have to be corrected since the operator is at fault.
• don't let the laboratory personnel influence you're judgement as to what

the best solution is.

• standard textbooks in sanitary engineering are the best source of

information.

• It is best to do nothing until the TNRCCC sends a violation notice.

(Ans- A. there is almost always a good technical solution. It may require considerable experience and time to learn what it is.

When the return sludge rate is too low, what happens?

• the aeration tank will not fill
• There will be insufficient organisms to treat the waste load entering the

aeration basin

• the activated sludge in the aerator will starve.
• the sludge blanket in the secondary clarifier could become too high.
• B and D (Ans- E. B and D

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