Lectures 6-7 Review

Which of the following is not true of Type 1 settling?

• Applies for low solids concentrations

• Involves particle interactions and increasing settling velocity

• Typical settling behaviour of large particles such as sand and gravel

• May occur during primary sedimentation

What are the three main forces which act on a particle during settling?

• Velocity, gravity, drag

• Gravity, drag, turbulence

• Velocity, turbulence, drag

• Gravity, buoyancy, drag

Which variable is a direct function of Reynold's number (flow regime) when calculating the terminal settling velocity of a particle?

• Drag coefficient

• Diameter

• Density

• Kinematic viscosity

If a particle enters the top of a settling basin, which settling velocity (v) would ensure removal?

• v < overflow rate

• v divided by overflow rate equals 0.5

• v times overflow rate is >10

• v >= overflow rate

For particles with settling velocity < overflow rate, which ratio is representative of removal?

• mass smallest particle/mass of largest particle

• settling velocity/overflow rate

• settling velocity/particle mass

• settling basin depth/settling basin length

Which of the following is an example of typical media types in a dual-media filter?

• coarse sand, fine sand

• coarse sand, gravel

• sand, anthracite

• anthracite, gravel

Which process does direct filtration exclude?

• Coagulation

• Flocculation

• Sedimentation

• Filtration

Why is it preferable to have course media at the top of a filter bed rather than fine media?

• Enables extended filter run times

• Reduces the accumulation of particles at the surface of the filter bed

• Enables utilization of entire depth of filter media

• All of the above

Which of the following options is not applied in the initiation of filter backwash?

• Headloss

• pH

• Run time

• Effluent turbidity

What undesirable effect might excessive backwashing rates have on granular media filters?

• Excessive bubbling

• Poor expansion of filter bed

• Media loss

• Reduced backwash duration