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WorksheetsDay 72-Dec6-worksheet-Btech-Physical treatmnt of water,sed. Tank
Total questions: 15
Worksheet time: 11mins
Which of the following impurities is primarily removed by screening in water treatment?
Colloidal solids
Dissolved gases
Floating large debris
Taste & odour causing compounds
The approach velocity at screens must be limited (0.8–1 m/s) mainly to:
Reduce turbulence and promote coagulation
Prevent flocs from breaking
Prevent forcing debris through screen openings
Prevent chemical reactions near bar racks
Flocculent settling (Type II) occurs when:
Particles settle individually without interaction
The entire mass settles as one unit
Coagulants cause particles to build flocs that settle faster
Particles compress due to the weight of upper layers
Which factor does NOT influence settling velocity?
Specific gravity of particles
Temperature of water
Horizontal flow velocity
Depth of sedimentation tank
In a horizontal-flow sedimentation tank, a particle is considered removed if:
It compresses at the tank bottom
It reaches any wall of the tank
It reaches the bottom before reaching the outlet
It attains equilibrium concentration in vertical profile
Tube settlers are used because they:
Allow high surface loading rates and long detention time
Produce turbulent flow to enhance mixing
Provide laminar flow and reduce settling depth requirement
Increase detention time above 8 hours
True or False: Settling velocity in sedimentation tanks is independent of tank depth.
True
False
True or False: In Type III settling, particles settle individually without interaction.
True
False
The inclination of coarse screens is generally kept between ___to____ degrees.
(a)
In Type IV settling, particles support the weight of upper layers; hence it is called (a) settling.
Tube settlers generally have detention time less than (a) minutes.
In sedimentation analysis, the horizontal-flow tank assumes that particle concentration in the vertical cross-section is (a) .
The settling velocity of particles with diameter greater than 1 mm is estimated using (a) equation.
In radial-flow sedimentation tanks, particle movement follows a (a) path.
Match the following treatment units with their primary functions.
Aeration
Removal of dissolved gases
Screening
Removal of suspended solids
Filtration
Removal of taste & odour
Chlorination
Disinfection
