The settling velocity of a spherical particle of diameter less than 0.1 mm as per Stock’s law, is__________________?
(A) Vs = 418 (Gs – Gw) d [(3T + 70)/100]
(B) Vs = 418 (Gs – Gw)d² [(3T + 70)/100]
(C) Vs = 218 (Gs – Gw)d² [(3T + 70)/100]
(D) Vs = 218 (Gs – Gw)d [(3T + 70)/100]
In the activated sludge process__________________?
(A) Aeration is continued till stability
(B) Aeration is done with an admixture of previously aerated sludge
(C) Sludge is activated by constant stirring
(D) Water is removed by centrifugal action
running partially full with central angle , For a circular sewer of diameter__________________?
(A) d/D = ½ (1 – –
(B) a/A
(C) r/R = [1 –
(D) All the above
If the discharge of a sewer running half is 628 1.p.s., i = 0.001, and n = 0.010, the diameter of the sewer, is__________________?
(A) 1.39 m
(B) 1.49 m
(C) 1.59 m
(D) 1.69 m
Sludge banks are formed if sewage is disposed of in____________________ ?
(A) Rivers
(B) Seas
(C) Lakes
(D) None of these
Chlorination of water is done for the removal of____________________?
(A) Bacterias
(B) Suspended solids
(C) Sediments
(D) Hardness
The arrangement made for passing the sewer line below an obstruction below the hydraulic gradient lines called ____________________?
(A) Inverted syphon
(B) Depressed sewer
(C) Sag pipe
(D) all of these
The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is___________________?
(A) 1.5
(B) 2.0
(C) 3.0
(D) 4.0
In a grit chamber of a sewage treatment plant ____________________?
(A) Flow velocity 0.15 m to 0.3 m/sec is kept
(B) Depth of 0.9 m to 1.20 m is kept
(C) One minute of detention period is kept
(D) All the above
Lead acetate test in sewer manhole is done to test the presence of ____________________?
(A) Methane gas
(B) Hydrogen sulphide
(C) Carbondioxide gas
(D) Diesel vapours