1 >>If the total hardness of water is greater than its total alkalinity, the carbonate hardness will be equal to ?
- (A) total alkalinity
- (B) total hardness
- (C) total hardness total alkalinity
- (D) non carbonate hardness
2 >>The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is about ?
- (A) 0.01 to 0.05 ppm
- (B) 0.05 to 0.5 ppm
- (C) 0.5 to 1.0 ppm
- (D) 1.0 to 5.0 ppm
3 >>The length of rectangular sedimentation tank should not be more than ?
- (A) B
- (B) 2B
- (C) 4B
- (D) 8B
4 >>Percentage of bacterial load that can be removed from water by the process of plain sedimentation is about ?
- (A) 10 to 25
- (B) 50
- (C) 75
- (D) 100
5 >>The settling velocity of a particle in a sedimentation tank depends on ?
- (A) depth of tank
- (B) surface area of tank
- (C) both depth and surface area of tank
- (D) none of the above
6 >>The settling velocity of a particle in a sedimentation tank increases if ?
- (A) particle size is decreased
- (B) the surface area of tank is increased
- (C) the depth of tank is decreased
- (D) none of the above
7 >>For a given discharge, the efficiency of sedimentation tank can be increased by ?
- (A) increasing the depth of tank
- (B) decreasing the depth of tank
- (C) increasing the surface area of tank
- (D) decreasing the surface area of tank
8 >>The detention period and overflow rate respectively for plain sedimentation as compared to sedimentation with coagulation are generally ?
- (A) less and more
- (B) less and less
- (C) more and less
- (D) more and more
9 >>Alum as a coagulant is found to be most effective when pH range of water is ?
- (A) 2 to 4
- (B) 4 to 6
- (C) 6 to 8
- (D) 8 to 10
10 >>The detention period in coagulation tanks is usually kept as ?
- (A) 1 to 2 minutes
- (B) 30 to 45 minutes
- (C) 2 to 6 hours
- (D) 2 to 6 days
11 >>The alum, when added as a coagulant in water ?
- (A) does not require alkalinity in water for flocculation
- (B) does not affect pH value of water
- (C) increases pH value of water
- (D) decreases pH value of water
12 >>The chemical most commonly used to increase speed of sedimentation of sewage is ?
- (A) sulphuric acid
- (B) copper sulphate
- (C) lime
- (D) sodium permanganate
13 >>In water treatment, rapid gravity filters are adopted to remove ?
- (A) dissolved organic substances
- (B) dissolved solids and dissolved gases
- (C) floating solids and dissolved inorganic solids
- (D) bacteria and colloidal solids
14 >>The rate of filtration in slow sand filters in million litres per day per hectare is about ?
- (A) 50 to 60
- (B) 100 to 150
- (C) 500 to 600
- (D) 1400 to 1500
15 >>The effective size of sand particles used in slow sand filters is ?
- (A) 0.25 to 0.35 mm
- (B) 0.35 to 0.60 mm
- (C) 0.60 to 1.00 mm
- (D) 1.00 to 1.80 mm
16 >>Air binding phenomena in rapid sand filters occur due to ?
- (A) excessive negative head
- (B) mud ball formation
- (C) higher turbidity in the effluent
- (D) low temperature
17 >>Period of cleaning of slow sand filters is about ?
- (A) 24 48 hours
- (B) 1012 days
- (C) 23 months
- (D) 12 year
18 >>The rate of Alteration of pressure filters is ?
- (A) less than that of slow sand filters
- (B) in between the filtration rate of slow sand filters and rapid sand filters
- (C) greater than that of rapid sand filters
- (D) equal to that of slow sand filters
19 >>Double filtration is used ?
- (A) to increase the filtration slow sand filters capacity of
- (B) to increase the filtration rapid sand filters capacity of
- (C) for isolated buildings like pools, hotels etc swimming
- (D) all of the above
20 >>Disinfection of water results in ?
- (A) removal of turbidity
- (B) removal of hardness
- (C) killing of disease bacteria
- (D) complete sterilization