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WorksheetsEVS - V
Total questions: 40
Worksheet time: 20mins
1. Uniformity coefficient of filter sand is given by
a) D50/D5
b) D50/D10
c) D60/D5
d) D60/D10
2. Zero hardness of water is achieved by
a) using lime soda process
b) excess lime treatment
c) Ion exchange method
d) using excess alum method
3. Self-cleansing velocity is
a) the minimum velocity of flow required to maintain a certain amount of solids in the flow
b) the maximum velocity of flow required to maintain a certain amount of solids in the flow
c) such flow velocity as would be sufficient to flush out any deposited solids in the sewers
d) such flow velocity as would be sufficient to ensure that sewage does not remain in the sewers
4. The following data pertain to a sewage sample :
Initial D.O. = 10 mg/l
Final D.O. = 2 mg/l
Dilution to 1%
The BOD of the given sewage sample is
a) 8 mg/l
b) 10 mg/l
c) 100 mg/l
d) 800 mg/l
5. Sewage sickness occurs when
a) sewage contains pathogenic organisms
b) sewage enter the water supply system
c) sewers get clogged due to accumulation of solids
d) voids of soil get clogged due to continuous application of sewage on a piece of land
6. In the design of storm sewers, “time of concentration” is relevant to determine the
a) rainfall intensity
b) velocity in the sewers
c) time of travel
d) area server by the sewer
7. Self-purification of running stream may be due to
a) sedimentation, oxidation and coagulation
b) dilution, sedimentation and oxidation
c) dilution, sedimentation and coagulation
d) dilution, oxidation and coagulation
8. The typical density in kg/cum (in situ) of well-compacted municipal solid waste in landfall is in the range of
a) 100 to 300
b) 310 to 500
c) 550 to 850
d) 900 to 1100
9. Two sources generate noise levels of 90 dB respectively. The cumulative effect of these two noise levels on the human ear is
a) 184 dB
b) 95.5 dB
c) 94 dB
d) 92 dB
10. Storage of water by impounding is required where
a) plenty of water is available in the stream in all seasons
b) excess of suspended and dissolved matters are presents in the water
c) there is a large variation in quantity of the river flow from time to time
d) the flow is uniform throughout the year but is insufficient
11. In a water treatment plant, dissolved iron and manganese can be removed from the water by
a) aeration
b) aeration and coagulation
c) aeration and flocculation
d) aeration and sedimentation
12. The effective size (ES) of sand and its uniformity coefficient (UC) are the usually specified parameters for sand filters, as compared to rapid sand filters,
a) ES is less but UC is more
b) ES is more but UC is less
c) Both ES and UC are more
d) Both ES and UC are less
13. Which one of the following is the purpose of providing a surge tank in a pipeline carrying water ?
a) to store water
b) to increase the pressure throughout the pipeline
c) to store overflowing water
d) to protect the pipeline against water hammer
14. The maximum flow occurs in an eggshaped sewers when the ratio of depth of flow to vertical diameter is
a) 0.33
b) 0.50
c) 0.95
d) 1.00
15. Fresh sludge has moisture content of 99% and, after thickening, its moisture content is reduced to 96%. The reduction in volume of sludge is
a) 3%
b) 5%
c) 75%
d) 97.5%
16. In the oxidation ditch, the excess sludge is taken to
a) anaerobic digester
b) aerobic digester
c) drying beds
d) incinerator
17. The two main gases liberated from an anaerobic sludge digestion tank would include
a) ammonia and carbon dioxide
b) carbon dioxide and methane
c) methane and hydrogen sulphate
d) ammonia and methane
18. Which one of the following sewage treatment units has a parshall flume ?
a) trickling filters
b) oxidation ditch
c) grit chamber
d) aerated lagoon
19. Which one of the following is least important in the activated sludge process ?
a) proper proportion of the return sludge from the secondary settling tank
b) adequate aeration in the biological reactors, so as to maintain certain minimum dissolved oxygen
c) proper food to micro-organisms (F:M) ratio
D) the sludge volume index of the return sludge to be less than 200
20. Aerosol is
a) carbon particles of microscopic size
b) dispersion of small solid or liquid particles in gaseous media
c) finely divided particles of ash
d) diffused liquid particles
21. Water presents in an artesian aquifer is usually
a) at sub atmosphere pressure
b) at atmosphere pressure
c) at 0.5 times of the atmosphere pressure
d) above atmosphere pressure
22. If the methyl orange alkalinity of water equals or exceeds total hardness, all of the hardness is
a) non-carbonate hardness
b) carbonate hardness
c) pseudo hardness
d) negative non-carbonate hardness
23. A commonly used handpump is the
a) centrifugal pump
b) reciprocating pump
c) rotary pump
d) axial flow pump
24. Service connection consists of
a) ferrule, stopcock and gooseneck
b) ferrule, check valve and gooseneck
c) stopcock, meter and sluice valve
d) sluice valve, check valve and matter
25. the correct sequence of processes in a water treatment plant for rural water supply is
a) chlorination, aeration, sedimentation, rapid sand filter
b) Coagulation, sedimentation, slow sand filter, chlorination
c) Coagulation, flocculation, clarification, pressure filter
d) Areation, plain sedimentation, slow sand filter, chlorination
26) The purpose of a proportional weir at the effluent end of a channel type grit removal unit is to
a) provide easy passage of solid particles
b) measure the rate of flow in the channel
c) keep the depth of flow in the channel above a certain value
d) maintain constant mean velocity in the channel
27. the trap use for a water closet is called
a) gully trap
b) p-trap
c) intercepting trap
d) anti-siphon trap
28. A circular sewer of diameter 1 m carries storm water to a depth of 0.75 m. The hydraulic radius is approximately
a) 0.3 m
b) 0.4 m
c) 0.5 m
d) 0.6 m
29. The sound pressure level for a jet plane on the ground with sound pressure of 2000µ bar should be
a) 60 decibel
b) 100 decibel
c) 140 decibel
d) 180 decibel
30. The controlling design parameter in the design of all settling tanks is
a) detention time
b) overflow time
c) percent removal of suspended solids
d) depth
31. The F/M ratio is controlled in the activated sludge process by adjusting the
a) flow rate
b) volume of aeration tank
c) amount of sludge wasting
d) BOD
32. Phosphorus can be removed from waste water by
a) rapid sand filteration
b) chlorine addition
c) carbon adsorption
d) ferric chloride addition
33.The sludge does not contain waste water from
a) bath rooms
b) wash basins
c) kitchen sinks
d) toilets
34. The water carried sewerage system removes
a) domestic sewage
b) industrial sewage
c) storm sewage
d) all of above
35. In a city the ratio of the drainage to sewage is 20, the percentage discharge passing through non-monsoon periods, is
a) 5
b) 10
c) 15
d) 20
36. the sewerage system originates from
a) house sewers
b) lateral sewers
c) branch sewers
d) main sewers
e) out fall sewers
37. the sewer which transports the sewage to the point of treatment, is called
a) house sewer
b) out fall sewer
c) branch sewer
d) lateral
e) main sewer
38. Pick up the in-correct statement from the following
a) Manholes are provided in sewer pipes at suitable intervals
b) Catch basins are generally provided in sewers for carrying discharge
c) Inlets are generally provided in all sewers
d) none of these
39. Before discharging the foul sewage into rivers, it is generally treated by
a) screening
b) sedimentation
c) oxidation
d) sludge digestion and disinfection
e) all of above
40. The sewers
a) must be of adequate size to avoid over flow
b) must flow under gravity ½ to ¾ full
c) must be laid at least 2 to 3m deep to collect water from the basements
d) all of above
