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Environmental Engineering MCQs | Environmental Engineering Short Questions(MCQs) & Answers

41 The design discharge for the combined sewer system shall be taken as
[A] equal to rainfall
[B] rainfall + DWF
[C] rainfall + 2 DWF
[D] rainfall + 6 DWF
Answer: rainfall + 2 DWF
42 The minimum and maximum diameters of sewers shall preferably be
[A] 15 cm and 100 cm
[B] 15 cm and 300 cm
[C] 30 cm and 450 cm
[D] 60 cm and 300cm
Answer: 15 cm and 300 cm
43 Most suitable section of sewer in separate sewage system is
[A] Rectangular Section
[B] Circular Section
[C] Standard Form Of Egg Shaped Sewer
[D] Modified Egg Shaped Section
Answer: Circular Section
44 The velocity of flow does not depend on
[A] Grade Of Sewer
[B] Length Of Sewer
[C] Hydraulic Mean Depth Of Sewer
[D] Roughness Of Sewer
Answer: Length Of Sewer
45 The effect of increasing diameter of sewer on the self cleansing velocity is
[A] To Decrease It
[B] To Increase It
[C] Fluctuating
[D] Nil
Answer: To Increase It
46 The characteristics of fresh and septic sewage respectively are
[A] Acidic And Alkaline
[B] Alkaline And Acidic
[C] Both Acidic
[D] Both Alkaline
Answer: Alkaline And Acidic
47 The pathogens can be killed by
[A] Nitrification
[B] Chlorination
[C] Oxidation
[D] None Of The Above
Answer: Chlorination
48 Sewage treatment units are normally designed for
[A] 5-10 years
[B] 15-20 years
[C] 30-40 years
[D] 40-50 years
Answer: 15-20 years
49 Standard BOD is measured at
[A] 20°C - 1day
[B] 25°C- 3day
[C] 20°C - 5day
[D] 30°C- 5day
Answer: 20°C - 5day
50 The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by
[A] TOD>BOD>COD
[B] TOD>COD>BOD
[C] BOD>COD>TOD
[D] COD>BOD>TOD
Answer: TOD>COD>BOD
51 Select the correct statement.
[A] 5 day BOD is the ultimate BOD
[B] 5 day BOD is greater than 4 day BOD keeping other conditions same
[C] 5 day BOD is less than 4 day BOD keeping other conditions same
[D] BOD does nof depend on time
Answer: 5 day BOD is less than 4 day BOD keeping other conditions same
52 In a BOD test, 1.0 ml of raw sewage was diluted to 100 ml and the dissolved oxygen concentration of diluted sample at the beginning was 6 ppm and it was 4 ppm at the end of 5 day incubation at 20°C. The BOD of raw sewage will be
[A] 100 ppm
[B] 200 ppm
[C] 300 ppm
[D] 400 ppm
Answer: 200 ppm
53 Dissolved oxygen in streams is
[A] Maximum At Noon
[B] Minimum At Noon
[C] Maximum At Midnight
[D] Same Throughout The Day
Answer: Maximum At Noon
54 The means of access for inspection and cleaning of sewer line is known as
[A] Inlet
[B] Manhole
[C] Drop Manhole
[D] Catch Basin
Answer: Manhole
55 Sewage treatment units are designed for
[A] Maximum Flow Only
[B] Minimum Flow Only
[C] Average Flow Only
[D] Maximum And Minimum Flow
Answer: Average Flow Only
56 Laying of sewers is usually done with the help of
[A] A Theodolite
[B] A Compass
[C] Sight Rails And Boning Rods
[D] A Plane Table
Answer: Sight Rails And Boning Rods
57 If the sewage contains grease and fatty oils, these are removed in
[A] Grit Chambers
[B] Detritus Tanks
[C] Skimming Tanks
[D] Sedimentation Tanks
Answer: Skimming Tanks
58 Generally the detention period for grit chambers is kept as
[A] 1 minute
[B] 5 minutes
[C] 2-4 hours
[D] 12 hours
Answer: 1 minute
59 Which of the following unit works in anaerobic conditions?
[A] Sludge Digestion Tank
[B] Sedimentation Tank
[C] Activated Sludge Treatment
[D] Trickling Filters
Answer: Sludge Digestion Tank
60 The working conditions in imhoff tanks are
[A] Aerobic Only
[B] Anaerobic Only
[C] Aerobic In Lower Compartment And Anaerobic In Upper Compartment
[D] Anaerobic In Lower Compartment And Aerobic In Upper Compartment
Answer: Anaerobic In Lower Compartment And Aerobic In Upper Compartment

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