Waste water Engineering

1: The settling velocity of a spherical particle of diameter less than 0.1 mm as per Stock's law, is

A. `V_S = 418 (G_S - G_W) d [(3T + 70)/(100)]`

B. `V_S = 418 (G_S - G_W) d^2 [(3T + 70)/(100)]`

C. `V_S = 218 (G_S - G_W) d^2 [(3T + 70)/(100)]`

D. `V_S = 218 (G_S - G_W) d [(3T + 70)/(100)]`

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2: For having central angle `alpha`, the area of cross-section of sewers running partially full, is

A. ` A = D^2/2 [ (pi alpha)/(180^circ) - sin alpha /2]`

B. ` A = D^2/4 [ (pi alpha)/(180^circ) - sin alpha /2]`

C. ` A = D^2/4[ (pi alpha)/(180^circ) - cos alpha /2]`

D. ` A = D^2/2 [ (pi alpha)/(180^circ) - cos alpha /2]`

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3: Boussinesq's equation for ascertaining unit pressure at a depth H on sewers due to traffic loads, is

A. `rho_t = (3H^3 P)/(2 pi Z^5 )`

B. `rho_t = (2H^3 P)/(3 pi Z^5 )`

C. `rho_t = (3H^3 P)/(2 Z^5 )`

D. `rho_t = (2 pi H^3 P)/(3Z^5 )`

E. none of these.

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4: In a sludge digestion tank if the moisture content of sludge V₁ litres is reduced from p₁ % to p₂ % the volume V₂ is

A. `(100 + P_1)/(100 - P_2) V_1`

B. `((100 - P_1)/(100 + P_2)) V_1`

C. `((100 - P_1)/(100 - P_2)) V_1`

D. `((100 + P_2)/(100 - P_1)) V_1`

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5: Hazin's formula `V_S = 418 (G_S - G_W) d [(2T + 70)/(100)]` is used for the settlement velocity of the particles of diameter

A. less than 0.01 mm

B. less than 0.05 mm

C. less than 0.1 mm

D. greater than 0.1 mm.

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