Font size
S
M
L
XL
WorksheetsD60 MASTER THE DAY
Total questions: 111
Worksheet time: 2hrs 51mins
Name
Class
Date
1.
What is the depth range of a cess pool typically?
a)
1–1.5 m
b)
1.8–3 m
c)
3.5–4.5 m
d)
0.8–1.2 m
2.
What is the minimum spacing required from a building for a cess pool?
a)
5–10 m
b)
15–20 m
c)
25–30 m
d)
10–12 m
3.
What is another name for inverted siphons in sewerage?
a)
Submerged culvert
b)
Depressed sewers
c)
Subsurface conduit
d)
Forced syphon
4.
What kind of tank is used for small groups of houses where no sewer network exists?
a)
Oxidation tank
b)
Septic tank
c)
Sedimentation tank
d)
Imhoff tank
5.
What is used for disposal of septic tank effluent through perforated pipes?
a)
Seepage trench
b)
Absorption trench
c)
Leach pit
d)
Filtration chamber
6.
Which material is filled in soak pits for filtration?
a)
Coarse sand
b)
Brick bats or stone aggregates
c)
Gravel & clay
d)
Fly ash
7.
The length of a septic tank is usually how many times its width?
a)
1.5–2 times
b)
2–3 times
c)
2.5–3.5 times
d)
3–4 times
8.
Which pipe material is suitable for septic tank inlet and outlet?
a)
Plastic
b)
Stoneware or asbestos
c)
HDPE
d)
Galvanized steel
9.
What is the typical diameter of inlet and outlet pipes in a septic tank?
a)
50 mm
b)
100 mm
c)
150 mm
d)
200 mm
10.
Baffle walls in large septic tanks are made of:
a)
RCC slabs
b)
Brick honeycomb walls
c)
PCC wall
d)
Timber baffle
11.
What is the thickness of RCC roofing slab for septic tanks?
a)
50 mm
b)
75 mm
c)
100 mm
d)
125 mm
12.
What is the shape of access opening provided in septic tanks?
a)
Hexagonal
b)
Circular
c)
Square
d)
Rectangular
13.
Which wire mesh is used at the top of ventilating pipe in septic tanks?
a)
Aluminium mesh
b)
Iron mesh
c)
Stainless steel mesh
d)
Mosquito-proof mesh
14.
The floor of a septic tank is usually laid with:
a)
Tiled flooring
b)
Cement concrete (1:2:4)
c)
Asphalt flooring
d)
RCC with steel mesh
15.
What is the flow rate considered for design when both sewage and sullage are connected?
a)
45–75 lpcd
b)
90–150 lpcd
c)
60–80 lpcd
d)
100–120 lpcd
16.
What is the typical sludge accumulation per capita per year in septic tanks?
a)
15 l
b)
30 l
c)
45 l
d)
60 l
17.
Which tank is designed for removal of floating grease and oils?
a)
Detritus tank
b)
Skimming tank
c)
Imhoff tank
d)
Primary clarifier
18.
The grit chamber removes particles with specific gravity more than:
a)
1.1
b)
2.0
c)
2.65
d)
3.0
19.
Which chamber in an Imhoff tank is responsible for sedimentation?
a)
Upper chamber
b)
Lower chamber
c)
Side chamber
d)
Circular tank
20.
What is the function of the digestion chamber in an Imhoff tank?
a)
Store scum
b)
Digest sludge
c)
Settle solids
d)
Separate grit
21.
What is the minimum capacity of digestion chamber in Imhoff tank per capita?
a)
27 litres
b)
57 litres
c)
75 litres
d)
100 litres
22.
Which component allows gases to escape in a septic tank?
a)
Baffle wall
b)
Ventilating pipe
c)
Inlet pipe
d)
Outlet pipe
23.
What is the main disadvantage of Imhoff tanks?
a)
Not effective for small cities
b)
Costly due to depth
c)
Requires aerobic conditions
d)
Cannot remove BOD
24.
Which tank has two separate compartments for sedimentation and digestion?
a)
Septic tank
b)
Imhoff tank
c)
Trickling filter
d)
Oxidation ditch
25.
What type of tank is now considered obsolete in modern practice?
a)
Septic tank
b)
Imhoff tank
c)
Skimming tank
d)
ASP tank
26.
Which screen type has bar spacing greater than 50 mm?
a)
Medium screen
b)
Coarse screen
c)
Fine screen
d)
Ultra fine screen
27.
How is the number of bars in a screen calculated?
a)
n
b)
n+1
c)
2n
d)
n–1
28.
Which screen type removes floating matter and 20% suspended solids?
a)
Fine screen
b)
Coarse screen
c)
Medium screen
d)
Ultrafine screen
29.
What device is used to reduce size of sewage particles by shredding?
a)
Comminutor
b)
Grinder
c)
Ventilator
d)
Aerator
30.
Why is grit removal done before shredding?
a)
To aerate sewage
b)
To prevent wear of shredders
c)
To remove BOD
d)
To settle solids
31.
Which device is not commonly used in India for sewage treatment?
a)
Screening chamber
b)
Comminutor
c)
Oxidation ditch
d)
Sludge tank
32.
Which tank has air diffusers to float light organic matter?
a)
Primary clarifier
b)
Skimming tank
c)
Detritus tank
d)
Aeration tank
33.
What is the detention period in a detritus tank?
a)
2–3 minutes
b)
3–4 minutes
c)
4–5 minutes
d)
5–6 minutes
34.
What is the velocity of flow in detritus tanks?
a)
0.2 m/s
b)
0.09 m/s
c)
0.3 m/s
d)
0.5 m/s
35.
Which flume is preferred for low head loss and accurate flow measurement?
a)
Sharp-crested weir
b)
Parshall flume
c)
V-notch flume
d)
Measuring pit
36.
Which tank is suitable only for small cities and institutions?
a)
Oxidation ditch
b)
Imhoff tank
c)
Septic tank
d)
Aeration tank
37.
Which material is used for access cover slabs in septic tanks?
a)
Cast iron
b)
RCC
c)
Masonry
d)
Timber
38.
What is the diameter of circular access openings in septic tanks?
a)
300 mm
b)
500 mm
c)
600 mm
d)
450 mm
39.
Why are access covers provided in septic tanks?
a)
To release gas
b)
To let rainwater in
c)
To cool the tank
d)
To allow sludge mixing
40.
Which type of sewer is used under pressure to cross obstacles?
a)
Spigot sewer
b)
Depressed sewer
c)
Pressure line
d)
Gravity sewer
41.
What is the slope percentage provided in the flooring of a septic tank?
a)
2–4%
b)
5–10%
c)
10–15%
d)
15–20%
42.
Which pipe is submerged 250–600 mm below liquid level?
a)
Vent pipe
b)
Inlet pipe
c)
Outlet pipe
d)
Inspection pipe
43.
The freeboard in a septic tank varies between:
a)
100–200 mm
b)
300–450 mm
c)
200–300 mm
d)
50–100 mm
44.
Which part of the septic tank is designed to digest settled solids?
a)
Inlet pipe
b)
Sludge zone
c)
Outlet pipe
d)
Access slab
45.
Which component prevents mosquitoes from entering the vent pipe?
a)
Wire mesh
b)
Mosquito-proof mesh
c)
Steel cover
d)
Rubber seal
46.
In Imhoff tank, what is the function of the scum chamber vent?
a)
Let air out
b)
Float solids
c)
Ventilate sludge
d)
Increase depth
47.
Why are honeycombed brick walls used in septic tanks?
a)
Provide access
b)
Distribute flow
c)
Allow scum to float
d)
Honeycomb strength
48.
Which shape is used for access cover besides circular?
a)
Hexagonal
b)
Rectangular
c)
Round
d)
Trapezoidal
49.
Which kind of screen removes particles sized between 6 to 40 mm?
a)
Coarse screen
b)
Medium screen
c)
Fine screen
d)
Ultrafine screen
50.
What is the key function of a grit chamber?
a)
BOD removal
b)
Heavy inorganic particles removal
c)
Gas escape
d)
Grease removal
51.
What are the ideal characteristics of grit particles?
a)
Specific gravity < 1.0
b)
Specific gravity > 2.65
c)
Size > 2 mm
d)
Biodegradable
52.
Which component is used to maintain uniform flow velocity in grit channels?
a)
Bar screen
b)
Proportional flow weir
c)
V-notch flume
d)
Sand trap
53.
Which screen type is located at the entry of a sewage treatment plant?
a)
Medium screen
b)
Fine screen
c)
Ultrafine screen
d)
Screen grid
54.
What is the typical flow velocity in a grit chamber?
a)
0.5 m/s
b)
0.3 m/s
c)
0.1 m/s
d)
0.2 m/s
55.
What causes scouring in grit chambers?
a)
Low velocity
b)
High velocity
c)
Low scum level
d)
Excess organic matter
56.
What is the maximum total depth of a septic tank including freeboard?
a)
1.25 m
b)
2.25 m
c)
2.75 m
d)
3.25 m
57.
Which unit follows grit chambers in sewage treatment?
a)
Skimming tank
b)
Primary clarifier
c)
Detritus tank
d)
Aeration tank
58.
What is the shape of grit chambers for effective grit removal?
a)
Circular
b)
Rectangular
c)
Trapezoidal
d)
Square
59.
Why are air diffusers used in skimming tanks?
a)
Aeration
b)
Float oil
c)
Mix sewage
d)
Remove BOD
60.
Which treatment removes soluble organic solids?
a)
Primary treatment
b)
Secondary treatment
c)
Tertiary treatment
d)
Sedimentation
61.
Match the following:
A. Screening - 1. Floating materials
B. Grit chamber - 2. Inorganic solids
C. Skimming tank - 3. Oil and grease
D. Clarifier - 4. Sedimentation
a)
A-1, B-2, C-3, D-4
b)
A-1, B-3, C-2, D-4
c)
A-2, B-1, C-4, D-3
d)
A-4, B-3, C-1, D-2
62.
What is the general flow rate considered for septic tank design per capita per day (with sewage & sullage)?
a)
45–75 lpcd
b)
90–150 lpcd
c)
120–150 lpcd
d)
30–45 lpcd
63.
Match the following:
A. Fine screen - 1. 1.5–6 mm spacing
B. Medium screen - 2. 6–40 mm spacing
C. Coarse screen - 3. > 50 mm spacing
D. Inclination - 4. 30°–60°
a)
A-1, B-2, C-3, D-4
b)
A-2, B-1, C-4, D-3
c)
A-3, B-2, C-1, D-4
d)
A-4, B-3, C-2, D-1
64.
Assertion: Comminutors reduce the size of sewage particles. Reason: They are used to remove floating oils and grease.
a)
Both A and R are true and R explains A
b)
Both A and R are true but R is not the correct explanation of A
c)
A is true, R is false
d)
Both A and R are false
65.
What is the typical spacing of bars in a medium screen?
a)
1–5 mm
b)
6–40 mm
c)
50–60 mm
d)
1.5–3 mm
66.
Which tank achieves 60–65% solids removal and 30–40% BOD removal?
a)
Skimming tank
b)
Imhoff tank
c)
Aeration tank
d)
Trickling filter
67.
Which unit is placed before primary clarifier?
a)
Grit chamber
b)
Comminutor
c)
Oxidation ditch
d)
Screening tank
68.
What happens if flow velocity in grit chamber decreases too much?
a)
Only inorganic settles
b)
Organic solids settle
c)
Scouring occurs
d)
No settling occurs
69.
Which method is used for sludge disposal from grit chambers?
a)
Landfilling
b)
Incineration
c)
Chemical treatment
d)
Burial
70.
What is the typical detention time in a septic tank?
a)
12–24 hrs
b)
24–48 hrs
c)
48–72 hrs
d)
6–12 hrs
71.
Which component is responsible for separating heavier inorganic materials?
a)
Skimming tank
b)
Grit chamber
c)
Parshall flume
d)
Sedimentation tank
72.
Why is detention time in septic tank longer than primary clarifier?
a)
To store scum
b)
To digest solids
c)
To digest sludge
d)
To allow floatation
73.
What is the flow velocity maintained in grit chambers to avoid scouring?
a)
0.1 m/s
b)
0.3 m/s
c)
0.5 m/s
d)
0.9 m/s
74.
Which type of treatment includes screening and skimming?
a)
Secondary treatment
b)
Preliminary treatment
c)
Tertiary treatment
d)
Disinfection
75.
What is the minimum area required for settling in a septic tank calculated from?
a)
Volume / width
b)
Volume / depth
c)
Clear space × area
d)
BOD × volume
76.
Which tank performs both sedimentation and digestion of sewage separately?
a)
Oxidation ditch
b)
Imhoff tank
c)
Septic tank
d)
Clarifier
77.
What is the main advantage of Imhoff tanks?
a)
Low construction cost
b)
Combines sedimentation and digestion
c)
Used in high-density areas
d)
High BOD removal
78.
What is the spacing range of fine screens in sewage treatment?
a)
1–3 mm
b)
1.5–6 mm
c)
6–12 mm
d)
12–24 mm
79.
Which operation reduces particle size and eliminates screenings?
a)
Aeration
b)
Comminution
c)
Sedimentation
d)
Screening
80.
In septic tank design, what does the volume of sludge zone depend on?
a)
BOD of effluent
b)
Sludge accumulation rate × users × cleaning interval
c)
Size of access opening
d)
Population size
81.
Which tank type is used when the sewage is under pressure and must pass under obstacles?
a)
Aeration tank
b)
Inverted siphon
c)
Main sewer
d)
Relief sewer
82.
Which particles are removed in grit chambers?
a)
Organic oils
b)
Inorganic heavy particles
c)
Biodegradable sludge
d)
Suspended solids
83.
What happens when velocity in grit chambers exceeds 0.3 m/s?
a)
Scouring occurs
b)
Floatables remain
c)
Good settling
d)
Odor increases
84.
Which chamber in the septic tank stores digested sludge?
a)
Inlet zone
b)
Sludge zone
c)
Outlet pipe
d)
Access opening
85.
What type of treatment is skimming tank part of?
a)
Primary treatment
b)
Preliminary treatment
c)
Secondary treatment
d)
Tertiary treatment
86.
Which flow rate is used for space calculation in septic tank when latrine is connected?
a)
25 litres/day
b)
45 litres/day
c)
60 litres/day
d)
90 litres/day
87.
What shape is typically adopted for skimming tanks?
a)
Circular
b)
Rectangular
c)
Trapezoidal
d)
U-shaped
88.
Why are sludge and scum not mixed in Imhoff tank?
a)
To accelerate flow
b)
To avoid re-mixing
c)
To allow digestion
d)
To ensure anaerobic condition
89.
What is the freeboard provided in Imhoff tank sedimentation chamber?
a)
15 cm
b)
45 cm
c)
60 cm
d)
75 cm
90.
Which of the following is true regarding preliminary treatment?
a)
Removes fine organics
b)
Removes heavy inorganic solids
c)
Reduces BOD by 80%
d)
Only used in small cities
91.
Which unit removes 60–65% suspended solids in sewage?
a)
Detritus tank
b)
Primary clarifier
c)
Trickling filter
d)
Septic tank
92.
Which screen type requires manual cleaning and is used in older plants?
a)
Rotating screen
b)
Bar screen
c)
Fine screen
d)
Mechanical screen
93.
Which parameter is used to estimate average daily sewage flow for septic tank design?
a)
Sludge volume
b)
Per capita water supply
c)
Sludge accumulation rate
d)
Peak hourly flow
94.
What is the function of a baffle wall in a septic tank?
a)
Support the tank roof
b)
Control sludge and scum
c)
Aid in drainage
d)
Allow aeration
95.
What is the role of the clarifier in sewage treatment?
a)
Increase BOD
b)
Remove suspended solids
c)
Increase solids
d)
Kill pathogens
96.
Which tank in sewage treatment is airtight and anaerobic?
a)
Grit chamber
b)
Septic tank
c)
Imhoff tank
d)
Sedimentation tank
97.
What is the purpose of providing a vent pipe in a septic tank?
a)
To release water
b)
Release gases
c)
Block mosquitoes
d)
Prevent flooding
98.
Which unit typically precedes secondary treatment units?
a)
Aeration tank
b)
Screening unit
c)
Trickling filter
d)
Oxidation ditch
99.
Which component in the septic tank helps prevent scum from escaping?
a)
Floor slab
b)
Baffle wall
c)
Roof slab
d)
Vent pipe
100.
What causes the release of gases like methane in septic tanks?
a)
Sedimentation
b)
Anaerobic digestion
c)
Aerobic process
d)
Air circulation
101.
Which operation occurs in the lower chamber of Imhoff tank?
a)
Sedimentation
b)
Digestion
c)
Aeration
d)
Chlorination
102.
Which of the following is NOT removed in screening?
a)
Sludge
b)
Grease
c)
Floating leaves
d)
Sand
103.
Which layer forms above settled sludge in a septic tank?
a)
Sludge
b)
Scum
c)
Ash
d)
Grease
104.
What causes the foul smell in cess pools?
a)
Proper ventilation
b)
Bad maintenance
c)
Organic overload
d)
Algae growth
105.
What is the typical cleaning frequency of septic tanks?
a)
Every 3 months
b)
Every 6 to 12 months
c)
Annually
d)
Weekly
106.
What is the main problem with cess pools?
a)
High BOD
b)
Foul odor and overflow
c)
Gas accumulation
d)
Dryness
107.
What happens if a grit chamber operates at high velocity?
a)
Better separation
b)
Scouring of walls
c)
Settling grit
d)
Pipe choking
108.
What is the recommended slope of septic tank floor?
a)
1–3%
b)
5–10%
c)
10–15%
d)
15–20%
109.
Which item is not part of preliminary treatment?
a)
Skimming tank
b)
Chlorination
c)
Screening
d)
Comminutor
110.
What does scouring in grit chambers lead to?
a)
Efficient sedimentation
b)
Floating organic solids
c)
Pipe erosion
d)
Increase flow velocity
111.
Which IS standard specifies septic tank dimensions?
a)
IS 10711
b)
IS 2470
c)
IS 456
d)
IS 800
Reset
