List Of 100 Environmental Engineering Objective Questions Part – 2
1.The type of valve which is provided to control the flow of water in the distribution system at street corners and where the pipe lines intersect is
check valve
sluice valve
safety valve
scour valve
ANSWER : s:b
2.The main disadvantage of cement concrete sewers is
less strength
difficulty in construction
difficulty in transportation due to heavy weight
less life
ANSWER : : difficulty in transportation due to heavy weight
3.If the time of concentration is 9 minutes, then the intensity of rainfall according to British Ministry of Health formula will be
4 mm/hr
lOmm/hr
20 mm/hr
40 mm/hr
ANSWER : : 40 mm/hr
4.The type of valve which allows water to flow in one direction but prevents its flow in the reverse direction is
reflux valve
sluice valve
air relief valve
pressure relief valve
ANSWER : : reflux valve
5.The design discharge for the separate sewer system shall be taken as
equal to dry weather flow (DWF)
2xDWF
3 x DWF
6xDWF
ANSWER : : 6xDWF
6.An egg shaped section of sewer
is economical than circular section
provides self cleansing velocity at low discharges
is more stable than circular section
is easy to construct
ANSWER : : provides self cleansing velocity at low discharges
7.A sewer that receives the discharge of a number of house sewers is called
house sewer
lateral sewer
intercepting sewer
submain sewer
ANSWER : : lateral sewer
8.Which of the following sewers is preferred for combined system of sewage ?
circular sewer
egg shaped sewer
rectangular sewer
none of the above
ANSWER : : egg shaped sewer
9.The velocity of flow does not depend on
grade of sewer
length of sewer
hydraulic mean depth of sewer
roughness of sewer
ANSWER : : length of sewer
10.The design discharge for the combined sewer system shall be taken as
equal to rainfall
rainfall + DWF
rainfall + 2 DWF
rainfall + 6 DWF
ANSWER : : rainfall + 2 DWF
11.Scour valves are provided
at street corners to control the flow of water
at every depression and dead ends to drain out the waste water that may collect there
at the foot of rising main along the slope to prevent back running of water
at every summit of rising mains
ANSWER : : at every depression and dead ends to drain out the waste water that may collect there
12.The time of concentration is defined as
the time taken by rainfall water to run from most distant point of water shed to the inlet of sewer
the time required for flow of water in sewer to the point under consideration
sum of (a) and (b)
difference of (a) and (b)
ANSWER : : sum of (a) and (b)
13.Average rate of water consumption perhead per day as per Indian Standard is
100 litres
135 litres
165 litres
200 litres
ANSWER : : 135 litres
14.A pipe conveying sewage from plumbing system of a single building to common sewer or point of immediate disposal is called
house sewer
lateral sewer
main sewer
submain sewer
ANSWER : : house sewer
15.The minimum and maximum diameters of sewers shall preferably be
15 cm and 100 cm
15 cm and 300 cm
30 cm and 450 cm
60 cm and 300cm
ANSWER : : 15 cm and 300 cm
16.For a country like India, where rainfall is mainly confined to one season, the suitable sewerage system will be
separate system
combined system
partially combined system
partially separate system
ANSWER : : separate system
17.Sewerage system is usually designed for
10 years
25 years
50 years
75 years
ANSWER : : 25 years
18.Most suitable section of sewer in separate sewage system is
rectangular section
circular section
standard form of egg shaped sewer
modified egg shaped section
ANSWER : : circular section
19.The water carriage system of collection of waste product
is cheaper in initial cost than dry conservancy system
requires treatment before disposal
creates hygenic problem
all of the above
ANSWER : : requires treatment before disposal
20.Which of the following methods of analysis of water distribution system is most suitable for long and narrow pipe system ?
circle method
equivalent pipe method
Hardy cross method
electrical analysis method
ANSWER : : equivalent pipe method
21.The specific gravity of sewage is
much greater than 1
slightly less than 1
equal to 1
slightly greater than 1
ANSWER : : slightly greater than 1
22.The suitable system of sanitation for area of distributed rainfall throughout the year with less intensity is
separate system
combined system
partially separate system
partially combined system
ANSWER : : combined system
23.The method of analysis of distribution system in which the domestic supply is neglected and fire demand is considered is
circle method
equivalent pipe method
electrical analysis method
Hardy cross method
ANSWER : : circle method
24.The slope of sewer shall be
given in the direction of natural slope of ground
given in the direction opposite to natural slope of ground
zero
steeper than 1 in 20
ANSWER : : given in the direction of natural slope of ground
25.The self cleansing velocity for all sewers in India is usually
less than 1.0 m/sec
1.0 m/sec to 1.2 m/sec
1.5 m/sec to 2.0 m/sec
3.0 m/sec to 3.5 m/sec
ANSWER : : 1.0 m/sec to 1.2 m/sec
26.Settling velocity increases with
specific gravity of solid particles
size of particles
depth of tank
temperature of liquid
ANSWER : : depth of tank
27.The type of sewer which is suitable for both combined and separate system is
circular sewer
egg shaped sewer
horse-shoe type sewer
semi-elliptical sewer
ANSWER : : egg shaped sewer
28.Laying of sewers is usually done with the help of
a theodolite
a compass
sight rails and boning rods
a plane table
ANSWER : : sight rails and boning rods
29.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
100 ppm
200 ppm
300 ppm
400 ppm
ANSWER : : 200 ppm
30.Dissolved oxygen in streams is
maximum at noon
minimum at noon
maximum at midnight
same throughout the day
ANSWER : : maximum at noon
31.The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by
TOD>BOD>COD
TOD>COD>BOD
BOD>COD>TOD
COD>BOD>TOD
ANSWER : : TOD>COD>BOD
32.Which of the following retards the self purification of stream ?
higher temperature
sunlight
satisfying oxygen demand
none of the above
ANSWER : s:d
33.The ratio of 5 day BOD to ultimate BOD is about
1/3
2/3
3/4
1.0
ANSWER : : 2/3
34.The effect of increasing diameter of sewer on the self cleansing velocity is
to decrease it
to increase it
fluctuating
nil
ANSWER : : to increase it
35.The pathogens can be killed by
nitrification
chlorination
oxidation
none of the above
ANSWER : : chlorination
36.The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is
1 ppm
4 ppm
10 ppm
40 ppm
ANSWER : : 4 ppm
37.The means of access for inspection and cleaning of sewer line is known as
inlet
manhole
drop manhole
catch basin
ANSWER : s:b
38.The characteristics of fresh and septic sewage respectively are
acidic and alkaline
alkaline and acidic
both acidic
both alkaline
ANSWER : : alkaline and acidic
39.Sewage treatment units are normally designed for
5-10 years
15-20 years
30-40 years
40-50 years
ANSWER : : 15-20 years
40.Select the correct statement.
5 day BOD is the ultimate BOD.
5 day BOD is greater than 4 day BOD keeping other conditions same.
5 day BOD is less than 4 day BOD keeping other conditions same.
BOD does nof depend on time.
ANSWER : : 5 day BOD is less than 4 day BOD keeping other conditions same.
41.Facultative bacteria are able to work in
presence of oxygen only
absence of oxygen only
presence as well as in absence of oxygen
presence of water
ANSWER : : presence as well as in absence of oxygen
42.The rate of BOD exerted at any time is
directly proportional to BOD satisfied
directly proportional to BOD remain-ing ,
inversely proportional to BOD satisfied
inversely proportional to BOD re-maining
ANSWER : : directly proportional to BOD remain-ing ,
43.The most commonly used sewer under culverts is
circular brick sewer
circular cast iron sewer
semi-elliptical sewer
horse-shoe type sewer
ANSWER : : circular brick sewer
44.Corrosion in concrete sewers is caused by
septic conditions
dissolved oxygen
chlorine
nitrogen
ANSWER : : septic conditions
45.The relative stability of a sewage sample, whose dissolved oxygen is same as the total oxygen required to satisfy BOD, is
1
100
infinite
zero
ANSWER : : 100
46.Sewage treatment units are designed for
maximum flow only
minimum flow only
average flow only
maximum and minimum flow
ANSWER : : average flow only
47.Standard BOD is measured at
20�C – 1day
25�C- 3day
20�C – 5day
30�C- 5day
ANSWER : : 20�C – 5day
48.Generally the detention period for grit chambers is kept as
1 minute
5 minutes
2-4 hours
12 hours
ANSWER : : 1 minute
49.If Biochemical oxygen demand (BOD) of a town is 20000 kg/day and BOD per capita per day is 0.05 kg, then population equivalent of town is
1000
4000
100000
400000
ANSWER : : 400000
50.If the sewage contains grease and fatty oils, these are removed in
grit chambers
detritus tanks
skimming tanks
sedimentation tanks
ANSWER : : skimming tanks
51.The pipe which is used to carry the discharge from sanitary fittings like bath rooms, kitchens etc. is called
waste pipe
soil pipe
vent pipe
antisiphonage pipe
ANSWER : : waste pipe
52.The biochemical treatment of sewage effluents is essentially a process of
oxidation
dehydration
reduction
alkalinization
ANSWER : : oxidation
53.The detention period for oxidation ponds is usually kept as
4-8 hours
24 hours
10 to 15 days
3 months
ANSWER : : 10 to 15 days
54.The gas from sludge digestion tank is mainly composed of
nitrogen
carbon dioxide
hydrogen sulphide
methane
ANSWER : : methane
55.Sludge volume index is defined as the ratio of
percentage of sludge by volume to percentage of suspended solids by weight
percentage of sludge by volume to percentage of total solids by weight
percentage of suspended solids by weight to percentage of sludge by volume
percentage of total solids by weight to percentage of sludge by volume
ANSWER : : percentage of sludge by volume to percentage of suspended solids by weight
56.The maximum efficiency of BOD removal is achieved in
oxidation pond
oxidation ditch
aerated lagoons
trickling filters
ANSWER : : oxidation ditch
57.For satisfactory working of a sludge digestion unit, the pH range of digested sludge should be maintained as
4.5 to 6.0
6.5 to 8.0
8.5 to 10.0
10.5 to 12.0
ANSWER : s:b
58.The main disadvantage of oxidation pond is that
large area is required for construction
maintenance and operation cost are high
BOD removal is very low
none of the above
ANSWER : : large area is required for construction
59.The working conditions in imhoff tanks are
aerobic only
anaerobic only
aerobic in lower compartment and anaerobic in upper compartment
anaerobic in lower compartment and aerobic in upper compartment
ANSWER : : anaerobic in lower compartment and aerobic in upper compartment
60.Most of the bacteria in sewage are
parasitic
saprophytic
pathogenic
anaerobic
ANSWER : : saprophytic
61.To divert excessive flow from combined sewers, the most commonly used weir is a
cipoletti weir
broadcrested weir
leaping weir
submerged weir
ANSWER : : leaping weir
62.A pipe which is installed in the house drainage to preserve the water seal of traps is called
vent pipe
antisiphonage pipe
waste pipe
soil pipe
ANSWER : : antisiphonage pipe
63.Composting and lagooning are the methods of
sludge digestion
sludge disposal
sedimentation
filtration
ANSWER : : sludge disposal
64.When there is no recirculation of sewage, then recirculation factor is
0
1
infinity
none of the above
ANSWER : : 1
65.In facultative stabilization pond, the sewage is treated by
aerobic bacteria only
algae only
dual action of aerobic bacteria and anaerobic bacteria
sedimentation
ANSWER : : dual action of aerobic bacteria and anaerobic bacteria
66.Septic tank is a i) settling tank ii) digestion tank iii) aeration tank The correct answer is
only (i)
(i) and (ii)
(i) and (iii)
only (iii)
ANSWER : : (i) and (ii)
67.For the same solid content, if the quantity of sludge with moisture content of 98% is X, then the quantity of sludge with moisture content of 96% will be
X/4
X/2
X
2X
ANSWER : : X/2
68.For normal sludge, the value of sludge index for Indian conditions is
0 to 50
50 to 150
150 to 350
350 to 500
ANSWER : : 150 to 350
69.The process of lagooning is primarily a means of
reducing the excessive flow in sewers
disposing of sludge
increasing the capacity of storage re-servoirs
increasing flow of sewage through imhoff tanks
ANSWER : : disposing of sludge