M.Sc. (Semester II) (CBCS) Examination Nov/Dec-2018
Environmental Science
WATER AND WASTE WATER ENGINEERING
Time: 2½ Hours Max. Marks: 70
Instructions: Answer any five questions.
All questions carry equal marks.
Question No. 1 is compulsory.
Attempt any two from Q. No. 3 and 4.
Attempt any two from Q. No. 6 and 7.
Q.1 Rewrite the sentences by choosing correct answer from given alternatives: 14
The average temperature of sewage in India, is
10oC 15oC
20oC 25oC
In the activated sludge process
Aeration is continued till stability
Aeration is done with an admixture of previously aerated sludge
Sludge is activated by constant stirring
Water is removed by centrifugal action
In septic tanks,
Free board of 0.3 m may be provided
The baffles or tees are extended up to top level of scum
The clear space between the baffle top and covering slab is about 7.5 cm
All of the above
Primary treatment of sewage consists of removal of
Large suspended organic solids Oil and grease
Sand and girt Floating materials
The temperature affects the
Biological activity of bacteria in sewage
Solubility of gases in sewage
Viscosity of sewage
All of the above
The maximum depth of sedimentation tanks, is kept
3 m 3.5 m
4 m 4.5 m
If the depletion of oxygen is found to be 5 ppm after incubating a 2.5
solution of sewage sample for 5 days at 21oC, B.O.D. of the sewage is
50 ppm 100 ppm
150 ppm 200 ppm
The pH value of fresh sewage is usually
Equal to 7 More than 7
Less than 7 Equal to zero
Acid value is also called is
Acid number Base number
Neutralization number Basic number
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SLR-VI-290
10) If the depletion of oxygen is found to be 5 ppm after incubating a 2.5%
solution of sewage sample for 5 days at 21oC, B.O.D. of the sewage is
50 ppm 100 ppm
150 ppm 200 ppm
11) 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 0.3m/minute
All of the above
12) No treatment of the sewage is given if dilution factor is
Less than 150 Between 150 to 200
Between 200 to 300 More than 500
13) For the COD test of sewage, organic matter is oxidized by K2Cr2O7 in the
presence of
H2SO4 HNO3
HCl None of these
14) 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 of the above
Q.2 Briefly explains the various methods of ASP? 14
Q.3 Explain the various methods of Chlorination? Add a note on dechlorination? 14
Q.4 Explain the process and design aspect of CSTR digester with neat labeled
diagram.
14
Q.5 Write a short note on the following: 14
Bar Screening
Nano filtration
Q.6 Write in with suitable illustration on the following:- 14
Principles, applications and designing aspects of surface aeration
Principles, applications and deigning aspects of Primary Setting Tank
Q.7 Write an account on the following:- 14
Explain the demerits of attached growth aerobic treatment methods.
Principles, applications and designing aspects of reverse osmosis techniques.