Multiple choice Flashcards
B
For domestic wastewater, gas production in a well operated anaerobic digester should be in the vicinity of:
A) 1 CU FT of gas per day per pound of volatile matter destroyed.
B) 10 BTU per pound of dry solids at 70% volatile
C) one cubic foot of gas per capita per day
D) 50 BTU per cubic foot
E) All of the above
C
The flow through rate for grit channel is usually: A) 20 seconds to 1.0 minute B) 2 feet per second C) 1 foot per second D) 30 days, depending on temperature E) none of the above
D
Under normal conditions, the maximum pounds of chlorine gas that can be drawn from a 150 lb. cylinder is: A) 10 lbs/day B) 20 lbs/day C) 30 lbs/day D) 40lbs/day E) 50 lbs/day
B
Grit usually contains some organic matter which decomposes and creates odors. To facilitate disposal without nuisance, the organic matter is removed by washing methods. Commonly used is: A) aeration B) elutriation C) vacuum filtration D) wet oxidation E) none of the above
D
Proportional weird usually are located at: A) a magnetic flow meter B) stilling wells C) aerobic digester scum boxes D) grit chambers E) water treatment plants
C
The main difference between primary and secondary clarifies is the: A) overall dimensions B) type of outlet weirs C) density of sludge D) detention period E) flow distribution
E
Which of the following characteristics would be least helpful to an operator assessing the organic loading on his plant? A) solids concentration. B) BOD C) COD D) pH E) nitrogen content
B
The destruction of the larger portion of microorganisms, with the probability that all pathogenic organisms are killed, is called: A) digestion B) disinfection C) dilution D) sterilization E) disposal
D
In the activated sludge treatment process, there are many control methods. One method is to maintain a constant BOD : MLVSS ratio. This is common my referred to as: A) MCRT B) SA C) SA : SDI D) F:M E) TS:SRT
B
The successful operation of an activated sludge plant requires the maintenance of proper solids concentration in the system. One major limiting factor is: A) mixed liquor tank volume B) effluent flow C) air supply D) chlorine demand E) none of the above
C
Overloading if a stabilization pond may occur with a subsequent loss of DO. One of the operation-oriented short-term corrective measures is:
A) addition of sodium nitrate
B) decreasing the recirculating
C) building scum rafts
D) increasing the efficient weir height
E) too high a DO in the wastewater being allies to the filter
E
If bearings on a centrifugal pump are running hot, checking for over lubrication or under lubrication would be listed as a general preventative maintenance service. If the lubrication is satisfactory the next preventative maintenance check would be: A) replace bearings B) operate only when needed C) clean the pump D) recheck TCH E) inspect alignment of pump and motor
B
One of the reasons that air should be excluded from anaerobic digesters is because:
A) gas storage capacity is reduced
B) the entrance of air mixed with the gas produced in the digester could create an explosive mixture
C) air interferes with the action of the aerobic bacteria present
D) harmful or pathogenic bacteria may be brought in with the air
E) none of the above
B
The volatile acid/alkalinity relationship of an anaerobic digester is an indication of the buffer capacity of the digester contents. When the ratio starts to increase, it indicates: A) excellent digester operation B) decreases in alkalinity C) better methane production D) a decrease in volatile acids E) an increase in pH
E
In an on-line treatment facility having three aerobic digesters in series, which of the following statements would be true?
A) it is not necessary to aerate all 3 digesters
B) draw off supernatant from tanks #2 and #3 only
C) a dissolved oxygen level will be easier to maintain in tank #3 than in tank #1
D) sludge pumped to digester #3 must be thicker than sludge pimped to digester# 2 and #2 thicker than #1
E) all of the above statements are true
