MCQs on Sewage Treatment
1. 1. Question
1 points
The rate of accumulation of sludge in septic tanks is recommended as
o 1. 30 litres/person/year
o 2. 25 litres/person/year
o 3. 30 litres/person/month
o 4. 25 litres/person/month.
2. 2. Question
1 points
For the survival of fish in a river stream, the minimum dissolved oxygen is
prescribed
o 1. 10 ppm.
o 2. 3 PPm
o 3. 4 PPm
o 4. 5 PPm
3. 3. Question
1 points
The dimensions of a rectangular settling tank are : length 24 m, width 6 m and
depth 3 m. If 2 hour detention period for tanks is recommended, the rate of flow of
sewage per hour, is
o 1. 204 cu m
o 2. 212 cu m
o 3. 208 cu m
o 4. 216 cu m
4. 4. Question
1 points
When drainage to sewage ratio is 20, the peak dry weather flow is
o 1. slightly less than 5% of the design discharge
o 2. 20% of the design discharge
o 3. none of these.
o 4. slightly more than 5% of the design discharge
5. 5. Question
1 points
An inverted siphon is designed generally for
o 1. one pipe
o 2. two pipes
o 3. three pipes
o 4. four pipes.
6. 6. Question
1 points
A rainfall may be classified as acidic if its pH value is less or equal to
o 1. 5
o 2. 4
o 3. 7
o 4. 6
7. 7. Question
1 points
Self-cleansing velocity is
o 1. velocity of water at flushing
o 2. velocity at which no accumulation remains in the drains
o 3. velocity at dry weather flow
o 4. velocity of water in a pressure filter.
8. 8. Question
1 points
The non-clog pump which permits solid matter to pass out with the liquid sewage, is
o 1. pneumatic ejector
o 2. centrifugal pump
o 3. reciprocating pump
o 4. none of these.
9. 9. Question
1 points
The minimum recommended diameter of sewers, is
o 1. 15cm
o 2. 10cm
o 3. 20cm
o 4. 5cm
10. 10. Question
1 points
Aerobic bacterias
o 1. consume organic matter as their food
o 2. flourish in the presence of free oxygen
o 3. oxidise organic matter in sewage
o 4. all
11. 11. Question
1 points
The width of a rectangular sewer is twice its depth while discharging 1.5 m/sec. The
width of the sewer is
o 1. 0.88 m
o 2. 0.68 m
o 3. 1.36 m
o 4. 1.76 m.
12. 12. Question
1 points
If the over land flow from the critical point to the drain is 8 km and the difference in
level is 12.4 m, the inlet time is
o 1. 3 hours
o 2. 2 hours
o 3. 4 hours
o 4. 5 hours.
13. 13. Question
1 points
In a fully mechanised composting plant, involves
o 1. mechanized segregation
o 2. mechanized receipt
o 3. all of these.
o 4. mechanized pulverising of refuse
14. 14. Question
1 points
The screens are fixed
o 1. parallel to the direction of flow
o 2. perpendicular to the direction of flow
o 3. none of these.
o 4. at an angle 30 to 60 to the direction of flow
15. 15. Question
1 points
If D is the diameter of upper circular portion, the overall depth of a standard egg
shaped section, is
o 1. 1.25 D
o 2. 1.5 D
o 3. D
o 4. 1.75 D
16. 16. Question
1 points
Pick up the correct statement from the following :
o 1. The solubility of oxygen in sewage is 95% that is in distilled water
o 2. All
o 3. In treated sewage, 4 PPm of D.O. is essential
o 4. Only very fresh sewage contains some dissolved oxygen
17. 17. Question
1 points
For treating the sewage of a large city, you will recommend
o 1. sedimentation tanks with high rate trickling filters
o 2. a plant consisting of Imhoff tanks with low rate trickling filters
o 3. a sedimentation tank and an activated sludge treatment plant
o 4. none of these
18. 18. Question
1 points
If the diameter of sewer is 225 mm, the gradient required for generating self
cleansing velocity, is
o 1. 1 in 120
o 2. 1 in 60
o 3. 1 in 100
o 4. none of these.
19. 19. Question
1 points
If 2% solution of a sewage sample is incubated for 5 days at 20C and depletion of
oxygen was found to be 5 ppm, B.O.D. of the sewage is
o 1. 200 ppm
o 2. 225 ppm
o 3. None of these.
o 4. 250 ppm
20. 20. Question
1 points
In olden days the type of section adopted in trunk and out fall sewers was
o 1. horse shoe shaped
o 2. parabolic shaped
o 3. egg shaped
o 4. circular shaped.
The correct answer for each question is indicated by a .
1
INCORRECT Which of the following microorganisms is part of the Environmental Protection
Agency's microbial water contaminant candidate list for their ability to cause
severe health problems?
Calciviruses
A)
Escherichia coli O157:H7
B)
Vibrio cholerae
C)
All of the above
D)
2 CORRECT
In water treatment procedures, the purpose of coagulation and flocculation is to
Disinfect the water supply
A)
Remove microorganisms, organic matter, and suspended fine particles
B)
Soften the water by removing calcium and magnesium
C)
Remove taste and odor problems
D)
3
INCORRECT In the water purification process, chlorination may create disinfection by-
products (DBPs) that may be _________________.
Allergens
A)
Neurotoxins
B)
Carcinogens
C)
All of the above
D)
4 CORRECT
A major source of Giardia and Cryptosporidium contamination in the water
supply comes from
Cattle farms
A)
Canada geese
B)
Rodents
C)
Sewage
D)
5
INCORRECT According to the Total Coliform Rule, the maximum containment level goal
(MCLG) for total and fecal coliforms is set at
0
A)
100 cells/ml
B)
1000 cells/ml
C)
10,000 cells/ml
D)
6
INCORRECT Which of the following is true of indicator organisms, or microbes that can serve
as an index of possible water contamination by human pathogens?
It should be harmless to humans
A)
It should survive longer than the hardiest enteric pathogens
B)
The assay procedure for the indicator should have great specificity
C)
All of the above
D)
7
INCORRECT Which of the following is a common index organism of water contamination?
Coliforms
A)
Rhizobia
B)
Cyanobacteria
C)
Staphylococci
D)
8
INCORRECT The common, preferred method of evaluation of the microbiological
characteristics of water is
Most probable number (MPN)
A)
Biochemical oxygen demand (BOD)
B)
Membrane filter technique
C)
Defined substrate test
D)
9
INCORRECT Which of the following tests can be used to test for both coliforms and E. coli?
Most probable number (MPN)
A)
Membrane filtration technique
B)
Presence-absence (P-A) test
C)
Colilert defined substrate test
D)
10
INCORRECT The preferred indictor microorganism in brackish and marine waters is the
Staphylococci
A)
Coliforms
B)
Enterococci
C)
Cyanobacteria
D)
11
INCORRECT Which of the following techniques provides a quick, effective, and quantitative
means of identifying microbial contaminants in water?
Pure culture techniques
A)
Molecular techniques
B)
Serological methods
C)
None of the above
D)
12
INCORRECT Which of the following methods can be used to measure carbon removal during
wastewater treatment?
Total organic carbon (TOC) test
A)
Chemical oxygen demand (COD) test
B)
Biochemical oxygen demand (BOD) test
C)
All of the above
D)
13
INCORRECT Which major step in wastewater treatment prepares the wastewater for
treatment by physically removing the majority of solid material?
Primary treatment
A)
Secondary treatment
B)
Tertiary treatment
C)
All of the above
D)
14
INCORRECT Which major step in wastewater treatment promotes the biological
transformation of dissolved organic matter into microbial biomass and carbon
dioxide?
Primary treatment
A)
Secondary treatment
B)
Tertiary treatment
C)
All of the above
D)
15
CORRECT In the secondary step of wastewater treatment, ________ sludge is oxidized
and recycled under aerobic conditions.
Bulking
A)
Activated
B)
Aerated
C)
Oxidized
D)
16
INCORRECT Where is methane produced during the wastewater treatment process?
Anaerobic digestion
A)
Activated sludge system
B)
Trickling filters
C)
All of the above
D)
17
INCORRECT Which of the following is true of anaerobic digestion in the wastewater treatment
process?
Microbes consume large amounts of organic matter because
A) methanogenesis is energetically very inefficient
Methane can be produced as a by-product of the process
B)
Dried sludge can be sold as garden fertilizer
C)
All of the above
D)
18
INCORRECT The removal of nitrogen and phosphorus, compounds that promote
eutrophication, are removed during which stage of wastewater treatment?
Primary treatment
A)
Secondary treatment
B)
Tertiary treatment
C)
All of the above
D)
19
INCORRECT Nitrogen is removed from the water supply through which of the following
chemical reactions?
Denitrification
A)
Anammox
B)
Chlorination of ammonia
C)
All of the above
D)
20
INCORRECT Which of the following methods is used to measure the portion of total carbon
oxidized by microorganisms over a 5-day period at 20 degrees Celsius?
Total organic carbon (TOC) test
A)
Chemical oxygen demand (COD) test
B)
Biochemical oxygen demand (BOD) test
C)
All of the above
D)
21
CORRECT The combination of adsorption and biological predation of microbes is used in
which of the following wastewater treatment processes?
Wetland bioremediation systems
A)
Home septic tanks
B)
Municipal sewage systems
C)
All of the above
D)
22
INCORRECT Which of the following is true regarding home septic systems?
Most types of land are able to support septic systems
A)
Minimal nitrogen and phosphorus are produced
B)
Fractured rocks may result in contamination of well water with pathogens
C)
All of the above
D)
23
INCORRECT Which of the following is an outcome of biodegradation?
Minor changes in organic molecules with little change in its chemical
A) structure
Reversible fragmentation of complex organic molecules
B)
Complete mineralization of organic molecules into inorganic forms
C)
All of the above
D)
24
CORRECT The first step in the biodegradation of many contaminants is
Denitrification
A)
Dehalogenation
B)
Decarboxylation
C)
Transpeptidation
D)
25
INCORRECT Which of the following stereochemical structures is biodegraded at a much
slower rate?
Meta
A)
Ortho
B)
Para
C)
All of the above
D)
26
INCORRECT The change in the characteristics of a microbial community in response to the
addition of inorganic or organic substrates is called ______________.
Natural selection
A)
Directed evolution
B)
Acclimation
C)
Adaptive radiation
D)
27
INCORRECT Which of the following methods is an emerging approach to the bioremediation
of contaminants?
Microbial fuel cells
A)
Anaerobic digesters
B)
Industrial septic systems
C)
All of the above
D)
28
INCORRECT The addition of easily metabolized organic matter to a natural microbial
community with the purpose of increasing the rate of biodegradation is called
Nutrient amendment
A)
Nutrient stimulation
B)
Cometabolism
C)
Carbonization
D)
29
INCORRECT Which of these methods were used in the biodegradation of oil in Prince William
Sound following the Exxon-Valdez oil spill in 1989?
Addition of nitrogen and phosphorus to promote degradation
A)
Adjustment of the natural microbial community's composition
B)
Addition of bacterial predators and phages
C)
All of the above
D)
30
INCORRECT In ___________________, microorganisms that produce acids are used to
solubilize desirable metals.
Bioremediation
A)
Biodegradation
B)
Bioleaching
C)
Bioacidification
D)
31
INCORRECT The addition of known active microbes to soil or water with the purpose of
accelerating microbial processes is called
Biodegradation
A)
Bioremediation
B)
Bioaccentuation
C)
Bioaugmentation
D)
