environment water treatment Flashcards
Pick up the correct statement from the following :
[A]. Excess quantities of iron and manganese in water, cause discolouration of clothes
[B]. Lead and barium salts have toxic effect
[C]. Arsenic and selenium are poisonous to human health
[D]. Higher copper content affects the lungs
[E]. All the above. @
Pick up the correct statement from the following :
[A]. Excess quantities of iron and manganese in water, cause discolouration of clothes
[B]. Lead and barium salts have toxic effect
[C]. Arsenic and selenium are poisonous to human health
[D]. Higher copper content affects the lungs
[E]. All the above. @
Pick up the incorrect statement from the following regarding fire hydrants
[A]. Fire hydrants are fitted in water mains at 100 m to 150 m apart at fire
[B]. The minimum water pressure hydrants, is kept 1.5 kg/cm2
[C]. The water at pressure 1 to 1.5 kg/cm2 is made available for 4 to 5 hours for constant use
[D]. None of these. @
Pick up the incorrect statement from the following regarding fire hydrants
[A]. Fire hydrants are fitted in water mains at 100 m to 150 m apart at fire
[B]. The minimum water pressure hydrants, is kept 1.5 kg/cm2
[C]. The water at pressure 1 to 1.5 kg/cm2 is made available for 4 to 5 hours for constant use
[D]. None of these. @
Most commonly used pump for lifting water in water supply mains, is
[A]. axialflow pump @ [B]. reciprocating pump [C]. rotary type pump [D]. centrifugal pumps [E]. none of these
Most commonly used pump for lifting water in water supply mains, is
[A]. axialflow pump @ [B]. reciprocating pump [C]. rotary type pump [D]. centrifugal pumps [E]. none of these
Most satisfactory formula for an estimate of fire demand Q for a city of population P in thousands for Indian conditions, is
[A].
[B]. Q = 1640 P^0.5 (1 - 0.01 P^.5)
[C]. Q = 3180 P^0.5 @
[D]. none of these.
[C]. Q = 3180 P^0.5 @
kuchling formula
A high velocity of wash water is required for
[A]. rapid gravity filter with strainers [B]. rapid gravity filter without strainers @ [C]. slow sand filter with strainers [D]. slow sand filter without strainers [E]. none of these.
A high velocity of wash water is required for
[A]. rapid gravity filter with strainers [B]. rapid gravity filter without strainers @ [C]. slow sand filter with strainers [D]. slow sand filter without strainers [E]. none of these.
The maximum depth of sedimentation tanks is limited to
[A]. 2 m [B]. 3 m [C]. 4 m [D]. 5 m [E]. 6 m. @
Detention period: for plain sedimentation: 3 to 4 h, and for coagulated sedimentation: 2 to 2.5 h.
Velocity of flow: Not greater than 30 cm/min (horizontal flow).
Tank dimensions: L:B = 3 to 5:1. Generally L= 30 m (common) maximum 100 m. Breadth= 6 m to 10 m.
Circular: Diameter not greater than 60 m. generally 20 to 40 m.
Depth : 2.5 to 5.0 m (3 m).
Surface Overflow Rate: For plain sedimentation 12000 to 18000 L/d/m2 tank area; for thoroughly flocculated water 24000 to 30000 L/d/m2 tank area.
Slopes: Rectangular 1% towards an inlet and circular 8%.
The least thickness of class B cast iron (spun) pipe, is
[A]. 7.2 mm
[B]. 7.9 mm
[C]. 8.6 mm @
[D]. 10 mm.
8.6 is right answer and 7.9 is used for class A cast iron pipe.
The expected discharge to be obtained from an open well sunk in coarse sand is 0.0059 cumec. If the working depression head of the well is 3 m, the minimum diameter of the well, is
[A]. 2 m [B]. 2.25 m [C]. 2.50 m [D]. 2.75 m [E]. 3.00 m. @
Q = (k/A) * A * H
For coarse sand, k/A = 1,
For fine sand, k/A = 0.5,
For clay, k/A = 0.25.
Q = 0.0059 m^3/sec, Q = 0.0059 * 60 * 60 m^3/hour, A = (pi/4) * d^2.
If four fires break out in a city of population 40 lakhs and if each hydrant has three streams and duration of each fire is four hours, the total quantity of water required, is
[A]. 1880 kilo litres
[B]. 2880 kilo litres @
[C]. 3880 kilo litres
[D]. 4880 kilo litres.
Total quantity of water required = No of fires x Discharge x Time of each fire.
= 4 x (3 x 1000) x (4 x 60) = 2880000 liters = 2880 kilo liters. (where, 1000 liters/minute is discharge of each stream).
In slow sland filters, the turbidity of raw water can be removed only up to
[A]. 60 mg/litre @
[B]. 75 mg/litre
[C]. 100 gm/litre
[D]. 150 mg/litre.
Slow sand filter are not used for water turbidity greater than 50 NTU.
The best quality of filter material is obtained from quartzite if it does not loose weight when placed in hydro-chloric acid for 24 hours, more than
[A]. 5% @ [B]. 8% [C]. 10% [D]. 12% [E]. 15%.
5%
An area is declared drought affected if its mean rainfall is less than
[A]. 50% [B]. 60% [C]. 75% [D]. 80% [E]. 85%. @
The Indian Meteorological Department (IMD) has defined drought as a situation occurring in any area when the mean annual rainfall is less than 75% of the normal rainfall.
One degree of hardness of water means a content of salts of
[A]. 10.25 mg/litre [B]. 12.25 mg/litre [C]. 14.25 mg/litre @ [D]. 16.25 mg/litre. [E]. 20 mg/litre.
Hardness is represented in British scale, 1 degree hardness = 14.25 mg/l.
For french scale = 10 mg/l.
For amerucan scale = 17.15 mg/l.
Percussion drilling is unsuitable in
[A]. unconsolidated sand
[B]. unconsolidated gravel
[C]. quick sand
[D]. consolidated rocks. @
Percussion drilling is suitable for unconsolidated and consolidated formations:; sand, silt, stiff clay, sandstone, laterite and gravel layers depth up to 25m Unsuitable for rocks.
Normal values of overflow rate for plain sedimentation tank, is
[A]. 250 to 500 litres/hr/m2
[B]. 500 to 750 litres/hr/m2 @
[C]. 750 to 1000 litres/hr/m2
[D]. 1000 to 1250 litres/hr/m2.
Surface overflow rates:
Plain sedimentation :
V = 12 to 18 m3/day/m2.
V = 500 to 750 Liters/hr/m2.
Coagulation sediment:
V = 24 to 30 m3/day/m2. V = 1000 to 1250 Liters/hr/m2.
The period of cleaning of a slow sand filter, is usually
[A]. 5 to 10 days [B]. two weeks to three weeks [C]. one month to three months @ [D]. three months to six months [E]. one year.
The period of cleaning of a slow sand filter, is usually
[A]. 5 to 10 days [B]. two weeks to three weeks [C]. one month to three months @ [D]. three months to six months [E]. one year.
E. Coli bacterias die in water having pH greater than
[A]. 5.5 [B]. 6.5 [C]. 7.5 [D]. 8.5 [E]. 9.5 @
9.5 @
The valves provided at low points of pipes to drain off water quickly under gravity, are called
[A]. blow off valves
[B]. drain valves
[C]. sewer valves
[D]. all the above. @
Blow off valve. Drain valve. Sewer valve. Shut off valve. Flow off valve. Washout valve. Scour valve.
All are same.
The maximum pressure to which cast iron pipes may be subjected to, is
[A]. 3 kg/cm2
[B]. 5 kg/cm2
[C]. 7 kg/cm2 @
[D]. 10 kg/cm2.
It’s 0.77N/mm2 and 7kg/cm2.
The most commonly used chemical for dechlorination of water, is
[A]. sodium thiosulphate [B]. sodium bisulphate [C]. sodium sulphite @ [D]. sulphur-dioxide [E]. all the above.
C or A
For plain chlorination of water, the quantity of chlorine used, is
[A]. 0.1 mg/litre [B]. 0.2 mg/litre [C]. 0.3 mg/litre [D]. 0.4 mg/litre [E]. 0.5 mg/litre. @
Plain chlorination - 0.5mg/Lt.
Press chlorination - 0.1-0.5.
Post chlorination - 0.1-0.2.
The maximum permitted loss of head in a rapid sand filter, is
[A]. 1 m [B]. 2 m [C]. 3 m @ [D]. 4 m [E]. 5 m.
Slow sand filter:
Loss of head: 0.1 m ( initial limit).
: 0.8 to 1.2 m ( final limit).
Rapid sand filter :
Loss of head: 0.3 m ( initial limit).
: 2.5 to 3.0 m (final limit).
To control the growth of algae in reservoirs, the compound which is used, is
[A]. bleaching powder [B]. copper sulphate @ [C]. lime solution [D]. alum solution [E]. all the above.
To control the growth of algae in reservoirs, the compound which is used, is
[A]. bleaching powder [B]. copper sulphate @ [C]. lime solution [D]. alum solution [E]. all the above.
Pick up the wrong nominal internal diameter of cast iron (spun) pipes in mm from the following :
[A]. 300 [B]. 400 [C]. 500 [D]. 550 @ [E]. 600
Pick up the wrong nominal internal diameter of cast iron (spun) pipes in mm from the following :
[A]. 300 [B]. 400 [C]. 500 [D]. 550 @ [E]. 600
