M.Sc. (Semester II) (CBCS) Examination Oct/Nov-2017
Environmental Science
WATER AND WASTEWATER ENGINEERING
Day Date: Monday, 20-11-2017 Max. Marks: 70
Time: 10.30 AM to 01.00 PM
Instructions: Answer any Five Question.
All Questions carry equal marks.
Question No. 1 is Compulsory.
Attempt any two from Q.No.2, 3 and 4.
Attempt any two from Q.No.5, 6 and 7.
Q.1 Select the answer among the following 14
The pH value of fresh sewage is usually
Equal to 7 Less than 7
More than 7 Equal to zero
The maximum depth of sedimentation tanks, is kept
3 m 4 m
3.5 m 4.5
If the depletion of oxygen is found to be 5 ppm after incubating a 2.5%
solution of sewage sample for 5 days at 21°C, B.O.D. of the sewage is
50 ppm 150 ppm
100 ppm 200 ppm
For a continuous flow type of sedimentation tanks
Width of the tank is normally kept about 6 m
Length of the tank is normally kept 4 to 5 times the width
Maximum horizontal flow velocity is limited to 0.3 m/minute
All the above
No treatment of the sewage is given if dilution factor is
Less than 150 Between 200 to 300
Between 150 to 200 More than 500
For the COD test of sewage, organic matter is oxidized by K2Cr2O7 in
the presence of
H2SO4 HCI
HNO3 None of these
Pick up the correct statement from the following:
Hydrogen sulphide gas in excess, may cause corrosion of concrete
sewers
4 ppm of Dissolved Oxygen (D.O.) is ensured before discharging the
treated sewage in river
Solubility of oxygen in sewage is 95% of that of distilled water
All the above
Skimming tanks are
Used to remove the grease and oil
Those from which sludge is skimmed out
Tanks provided with self-cleansing screens
Improved version of grit chambers
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SLR-MI-393
The detention period for plain sedimentation water tanks, is usually
4 to 8 hours 16 to 24 hours
8 to 16 hours 24 to 36 hours
10) In a trickling filter
Filtration process is used Neither nor
Biological action is used Both and
11) For evaporation and measurement of settable solids, the apparatus
used, is
A jar A test tube
A breaker An Imhoff cone
12) The grit chambers of sewage treatment plants, are generally cleaned
after
2 days 12 days
7 days 14 days
13) Pick up the correct statement from the following:
Indore method of composting involves decomposition under aerobic
conditions
Bangalore method of composting involves decomposing under
anaerobic conditions
Fully stabilized refuse by the Bangalore method of compositing is a
powdery mass called humus
All of these
14) Kjeldahl nitrogen is a mixture of
Ammonia and nitrogen
Organic nitrogen and ammonia
Nitrogen and organic nitrogen
All the above
Q.2 Briefly explain the various method of population forecasting demographic,
arithmetical Progression and geometrical progression.
14
Q.3 Explain the various method of Filtration. Add a note on Reverse Osmosis? 14
Q.4 Explain the process and design aspect of Rotating biological Reactor
digester with neat labeled diagram.
14
Q.5 Write a short notes on following: 14
Bar Screening
Alkaline Stabilization of Sludge
Q.6 Write in with suitable illustration of the following: 14
Principles, applications and designing aspects of sedimentation.
Principles, applications and designing aspects of Activated Sludge
Process.
Q.7 Write an account on the following 14
Explain the various methods water and waste water disinfection.
Principles, applications and designing aspects of Clarifier.