Texas Basic Waste Water Operations Ch#08 Activated Sludge Process - Statistics

Answer Stats

Question	Answer	% Correct
Mixed liquor is the mixture of raw wastewater and microorganisms.	True	82%
The primary purpose of returning sludge is to have enough ________ in the aerator to match the food supply	microorganisms	73%
If the ________ loading on the plant is high, DO levels should be increased.	organic	73%
The five components of the activated sludge process are the oxygen supply system, aeration tank, clarifier, return sludge system, and waste sludge system.	True	73%
In the clarifier, the biological solids separate by gravity settling.	True	73%
Wasting removes excess solids, inert solids, and old or dead solids from the system.	True	73%
Process control parameters include dissolved oxygen, quantity and quality of solids, return rate, and wasting rate.	True	73%
The settled biological solids accumulate in the clarifier, then are always wasted from the process.	False	64%
________ are the smallest, most numerous, and most important of the activated sludge microorganisms.	Bacteria	55%
The clarifier should have very little scum, a sludge blanket in the bottom 1/4 of the clarifier depth, uniform weir flow, rising solids, and turbid supernatant.	False	55%
The ________ modification has no return sludge and the aeration tank is used as the clarifier.	sequential batch reactor	55%
Select the correctly labeled diagram below.		45%
The ________ modification of the activated sludge process has no primary clarifier, no digester, 24-hour aeration time, a low F/M ratio, and complete nitrification.	extended aeration	45%
The aeration tank should be observed weekly for a uniform aeration pattern, low amount of light colored foam, mild, earthy odor, and medium brown color.	False	45%
Normally, DO should be kept between 20 and 40 mg/L.	False	45%
________ settles gently and uniformly, compacts slowly, and has sharp edges like a sponge.	Quality sludge	45%
A simple method indicating when to waste is the ________.	30-minute settling test	36%
At least 1 mg/L DO should be kept in the aeration basin to maintain the health of the anaerobic microorganisms.	False	36%

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