This set of Environmental Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Biological Treatment of Waste Water – Secondary Treatment Systems”.
1. Secondary treatment systems can be used for biological degradation of ____________ in municipal waste waters.
a) Carbon dioxide and methane
b) Nitrogen and CO2
c) CO and methane
d) Organic pollutants
View Answer
Explanation: Organic pollutants are the most ubiquitous in the environment and they get accumulated in the environment and persist there because of their non-biodegradable properties and hence, secondary treatment methods using biological degradation is used for removal of organic pollutants in industrial and municipal waste waters, CO2, methane, Nitrogen, CO, can be removed by primary treatment methods.
2. Which of the following is another name given to conventional bio filters?
a) Percolating filter
b) Filter cake
c) Injection recovery
d) Bio-luminescence
View Answer
Explanation: Percolating filter, in which the waste trickles and which is oxidized and hence removed by biological degradation, Filter cake is the by-products of filtration left on the surface forming cakes, In-situ bioremediation involves certain techniques like Biosparging, Bioventing and Injection recovery whereas bioluminescence is an inherent light emitting property of biological organisms.
3. In the exposed lands, ______ are used to assist rotation during harsh weather conditions?
a) Wind vanes
b) Water sprayer
c) Flow bed
d) Motor drives
View Answer
Explanation: Wind vanes present on the rotator helps in the assist rotation during harsh weather conditions to even out rotation speed, Water sprayer is used to spray the waste water on the filter bed, which tends to filter out the pollutants and waste, motor drives are used to maintain speed variations.
4. Bio filters are fed with effluent only after ____________
a) Initial settlement
b) Bio-accumulation
c) Bio-degradation
d) Bio-magnification
View Answer
Explanation: Bio filters are fed with effluent only after initial settlement of the industrial effluent to avoid clogging of pores of filters also, it would block the distributor arm, Bio-magnification is the process by which toxic substances get deposited in the food chain, Immobilization uses Bio-accumulation processes, bio-degradation is the process that leads to degradation of compounds with the help of bacteria.
5. Compensation for lower temperatures can be achieved by reducing hydraulic and organic loading rates thereby increasing _____________
a) Retention time
b) Mixing
c) Aeration
d) Sparging
View Answer
Explanation: A temperature drop allows reduction in nitrification and removal of BOD, so, Compensation for lower temperatures can be achieved by reducing hydraulic and organic loading rates thereby increasing the retention time, more is the retention time, more will be the waste available for degradation hence, increasing the efficiency of waste water treatment, mixing, aeration and sparging doesn’t help with lowering the temperature or compensating with the temperature drop.
6. Effective preliminary treatment can also be used to remove the ____
a) Girt and rag
b) Carbon dioxide
c) Nutrients
d) Oxygen
View Answer
Explanation: Girt and rag has to be removed by preliminary treatment of the waste water to avoid clogging at the later treatment stages, Oxygen is sparged into the waste water to improve aerobic bio degradation, Carbon dioxide and nutrients are required for improving the efficiency of treatment.
7. Which of the following factors doesn’t influence biological treatment efficiency?
a) Surface area
b) Void space
c) Drainage
d) High BOD
View Answer
Explanation: Surface area, Void space within the filter leads to proper ventilation and drainage systems which influence the efficiency of the biological treatment system leading to faster and efficient treatment methods, high BOD levels in waste water contributes to high organic waste in the waste water.
8. Which of the following has the potential to ‘rough’ high strength industrial effluents prior to sewage discharge?
a) High rate bio filters
b) Conventional bio filters
c) Percolating filters
d) Rotating biological contractors
View Answer
Explanation: High rate bio filters, usually constructed as tower models treating food waste which has considerable potential to rough high strength industrial effluents prior to sewage discharge, Conventional bio filters are also called as Percolating filters and Rotating biological contractors have spherical shaped discs for carbonaceous oxidation of waste water.
9. Rotating biological contractors is used for carbonaceous oxidation as a ________
a) High rate bio filters
b) Conventional bio filters
c) Roughing filter
d) Filter cake
View Answer
Explanation: Roughing filter is used to pretreat water by removing suspended solids from the water that might clog the passage through bio filters, high rate bio filters usually constructed as tower models treating food waste which has considerable potential to rough high strength industrial effluents prior to sewage discharge, Conventional bio filters are also called as Percolating filters in which the waste trickles and is oxidized and hence removed by biological degradation, Filter cake is the by-products of filtration left on the surface forming cakes.
10. Organic overloading is a major problem associated with Rotating biological contractors.
a) True
b) False
View Answer
Explanation: Organic overloading is a major problem associated with Rotating biological contractors due to formation of excessive bio film on the surface of the spherical discs causing shaft and bearing collapse.
11. Absorbing oxygen from the air and pollutants from the wastewater can be decomposed aerobic microorganisms by which of the following methods?
a) High rate bio filters
b) Conventional bio filters
c) Percolating filter
d) Rotating biological contractors
View Answer
Explanation: Rotating biological contractors absorb oxygen from the air and pollutants from the wastewater when the spherical disc is in contact with the air and with the waste water respectively during its rotation which can be decomposed aerobic microorganisms, new microorganisms are fed and old microorganisms with declined level of activity is taken off, high rate bio filters usually constructed as tower models treating food waste which has considerable potential to rough high strength industrial effluents prior to sewage discharge whereas, Conventional bio filters are also called as Percolating filters in which the waste trickles and is oxidized and hence removed by biological degradation.
12. Up flow anaerobic sludge blanket reactor is an anaerobic digester which is used for wastewater treatment with the help of suspended sludge blanket filters.
a) True
b) False
View Answer
Explanation: An anaerobic digester called as Up flow anaerobic sludge blanket reactor which is used for wastewater treatment with the help of suspended sludge blanket filters, when the wastewater enters the reactor from the bottom, and flows upward, it passes through the suspended sludge blanket filter, this leads to high reduction in BOD.
13. Activated sludge is a type of wastewater treatment method for the treatment of sewage or industrial wastewaters using aeration and a microbial floc.
a) True
b) False
View Answer
Explanation: Activated sludge is a type of wastewater treatment method for the treatment of sewage or industrial wastewaters using aerobic microorganism especially bacteria, the bacteria deposits of settling tanks is seeded into incoming waste water and then the mixture is agitated for several hours in the presence of oxygen.
14. Which of the following is low energy consuming system for waste water treatment?
a) Biological wave contractor
b) Rotating biological contractors
c) High rate bio filters
d) Conventional bio filters
View Answer
Explanation: Biological wave contractor, known as bio wave based on deliberate generation of wave motion, hence, it is defined as a low energy consuming system for waste water treatment, high rate bio filters usually constructed as tower models treating food waste which has considerable potential to rough high strength industrial effluents prior to sewage discharge, Conventional bio filters are also called as Percolating filters in which the waste trickles and is oxidized and hence removed by biological degradation and Rotating biological contractors absorb oxygen from the air and pollutants from the wastewater when the spherical disc is in contact with the air and with the waste water respectively during its rotation which can be decomposed aerobic microorganisms.
15. ___________ is a natural method of waste water treatment.
a) Chemical method
b) Physical method
c) Water hyacinth pond
d) Rotating biological contractors
View Answer
Explanation: Water hyacinth pond natural method of waste water treatment using plantation of water hyacinth ponds used or secondary and tertiary treatment of waste water, Chemical method is harmful to the natural ecosystem and Physical method is time taking and tiresome, whereas, Rotating biological contractors used for treatment of pollutants from the wastewater using decomposed aerobic microorganisms.
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