Afive day B.O.D. at 15°C of the sewage of a town is 100 kg/day. If the 5 day B.O.D. per head at 15°C for standard sewage is 0.1 kg/day; the population equivalent is
1.100
2.1000
3.5000
4.10000
At the junction of sewers
1.top of smaller sewer is kept lower
2. top of larger sewer is kept lower
3.tops of both the sewers are at the same level
4.none of these
The pH value of sewage is determined with the help of
1.Imhoff Cone
2.turbidimeter
3.potentiometer
4.none of these
Design period of 40 to 50 years is adopted for
1.branch sewers
2.main sewers
3.trunk sewers
4.all the above.
In circular sewers if depth of flow is 02 times the full depth; the nominal gradient;
1. is only provided
2.is doubled
3.is trebled
4.is not enough.
Lead caulked joints are used for laying
1. stone ware pipes
2.earthern ware pipes
3.C.I. pipes
4.G.I. pipes.
Stoneware sewers are available in size
1.10 cm
2.15 cm
3.20 cm
4.25 cm
Depletion of ozone layer in the outer atmosphere may cause
1.lung cancer
2.skin cancer
3.bronchitis
4.heart disorder.
For trunk sewers more than 1.25 m in diameter; the ratio of the maximum daily sewage flow to the average daily sewage flow is assumed
1.1.5
2.2
3.2.5
4.3
If the peak discharge of a storm water drain (S.W. Drain) is e.xpected to exceed 150 cumecs; the free board to be provided; is
1.100 cm
2.90 cm
3.80 cm
4.50 cm
In trickling filter; B.O.D. is reduced to
1.30 to 40%
2.40 to 60%
3.60 to 80%
4. 80 to 90%
Inter-distance between ventilation columns in a sewer line is kept
1.25 to 50 m
2. 50 m to 100 m
3.100 m to 150 m
4.150 m to 300 m.
The pH value of fresh sewage is usually
1.equal to 7
2.more than 7
3.less than 7
4.equal to zero.
Pick up the correct statement from the following :
1.The water supply pipes carry pure water free from solid particles
2.The water supply pipes get clogged if flow velocity is less than self cleansing velocity
3.The sewers may be carried up and down the hills and valleys
4.None of these
Primary treatment of sewage consists of removal of
1.large suspended organic solids
2.oil and grease
3.sand and girt
4.none of these
Sluge banks are formed if sewage is disposed of in
1.rivers
2.seas
3.lakes
4.none of these
The density of population over 40 hectares is 250/hectare. If water supply demand per day is 200 litres and sewage discharge is 80% of water supply; the sewage flow in sewers of separate system; is
1. 0.05552 cumec
2.0.05554 cumec
3.0.0556 cumec
4. 0.0558 cumec.
The design period in years for pumping plants; is
1.1
2.2 to 3
3.3 to 5
4.5 to 10
The factor responsible for purification of sewage in river is
1.Hydrology
2.Dissolved oxygen in water
3.Temperature
4.Turbulence
The maximum spacing of manholes specified by Indian standard in sewers upto 0.3 m diameter is
1.20 m
2.30 m
3.45 m
4.75 m
The moisture content of a sludge is reduced from 90% to 80% in a sludge digestion tank. The percentage decrease in the volume of sludge; is
1.25%
2.50%
3.10%
4.5%
The rainfall at any place may be determined by
1.its intensity
2.its direction
3.its frequency
4.all the above.
The self-cleansing velocity of water flowing through pipe lines; is
1.2 metres/sec
2.1 metre/sec
3.0.5 metre/sec
4.0.25 metre/sec.
The sludge does not contain waste water from
1.bath rooms
2.wash basins
3.kitchen sinks
4.toilets.
The spacing of bars of perforations of fine screens used for the treatment of sewage; is
1.2 to 3 mm
2.3 to 5 mm
3.5 to10 mm
4.8 to 10 mm
The water carried sewerage system removes
1.domestic sewage
2. industrial sewage
3.storm sewage
4. all the above.
Ventilating shafts are provided to a sewer line at every
1.100 m
2.150 m
3.200 m
4.300 m
Which one of the following gases is most significant as air pollutant
1.Carbondioxide
2.Oxygen
3.Nitrogen
4.Sulphurdioxide.
Which one of the following part of human body withstands minimum radiation
1.thyroid
2.kidneys
3.eyes
4.ovaries/testis.
Which one of the following statements regarding septic tanks is wrong :
1.a gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided
2.the outlet invert level is kept 5 to 7.5 cm below the inlet invert level
3. the minimum width of septic level is 90 cm
4.the depth of tank is kept equal to its width