The detention time of a circular tank of diameter d and water depth H, for receiving the sewage Q per hour, is________________?
(A) d² (0.011d + 0.785H)/Q
(B) d (0.022d + 0.085H)/Q
(C) d (0.785d + 0.011H)/Q
(D) d (0.285d + 0.011H)/Q
pH value of sludge during alkaline regression stage, is__________________?
(A) More than 7
(B) Less than 7
(C) Less than 6
(D) More than 6
The moisture content of sludge is reduced from 90% to 80% in a sludge digestion tank. The percentage decrease in the volume of sludge, is_______________?
(A) 25 %
(B) 50 %
(C) 10 %
(D) 5 %
Bio-chemical oxygen demand (BOD) for the first 20 days in generally referred to_______________?
(A) Initial demand
(B) First stage demand
(C) Carbonaceous demand
(D) All of these
If is the diameter of upper circular portion, the overall depth of New Egg shaped sewer section, Is_____________________?
(A) 1.250 D
(B) 1.350 D
(C) 1.425 D
(D) 1.625 D
For evaporation and measurement of settable solids, the apparatus used, is________________?
(A) A jar
(B) A breaker
(C) A test tube
(D) An Imhoff cone
For design of sewers, percentage of sewage discharge is assumed_____________________?
(A) 65 to 70%
(B) 70 to 75%
(C) 75 to 80%
(D) 85%
‘Cowl’ is provided at___________________?
(A) Lower end of ventilating column
(B) Upper end of ventilating column
(C) Upper end of the manhole
(D) First step in manhole
A drop manhole is provided if__________________?
(A) A sewer drops from a height
(B) A branch sewer joins the main sewer at higher level
(C) A lamp is inserted to check obstruction
(D) None of these
For detecting the nitrates in sewage, the colour may be developed by adding________________?
(A) Potassium permanganate
(B) Sulphuric acid and napthamine
(C) Phenol-di -sulphuric acid and potassium hydroxide
(D) None of these