# Test: Flocculation And Clarification

## 10 Questions MCQ Test Environmental Engineering | Test: Flocculation And Clarification

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Attempt Test: Flocculation And Clarification | 10 questions in 25 minutes | Mock test for Chemical Engineering preparation | Free important questions MCQ to study Environmental Engineering for Chemical Engineering Exam | Download free PDF with solutions
QUESTION: 1

### __________ is an operation designed to force agitation in the fluid and induce coagulation.

Solution:

Explanation: Flocculation is an agitating process in which destabilized particles are brought into contact to promote agglomeration.

QUESTION: 2

### The rate of change of velocity per unit distance normal to a section is called_______

Solution:

Explanation: Mean velocity gradient is given by G= (P/uv) 1/2 Where P= power dissipated, u= absolute viscosity, v= volume to which power is applied.

QUESTION: 3

### What is the dimension formula of mean velocity gradient?

Solution:

Explanation: Mean velocity gradient is expressed in metre per second/m or Sec-1, so it has dimension formula of 1/T.

QUESTION: 4

What is the desirable value of mean velocity gradient in a flocculator?

Solution:

Explanation: The desirable value of mean velocity gradient (G) in a flocculator is 20-75sec-1and for ‘Gt’ is 2*104 to 6*104 where ‘Gt’ is the ratio of power induced rate of flow to displace mean induced rate of flow.

QUESTION: 5

What is the normal value of the detention period adopted in a flocculator for design purpose?

Solution:

Explanation: The detention period in a flocculator for design purpose should be in the range of 10-40min and its normal value should be 30min.

QUESTION: 6

The design value of the velocity of flow in a flocculator is _______

Solution:

Explanation:The normal value of the velocity of flow in a flocculator is 0.4m/s and its range is 0.2-0.8m/s.

QUESTION: 7

What is the detention period of a clarifier used in the treatment of water?

Solution:

Explanation: The detention period of a clarifier is lower than in the plain sedimentation tank and its range is 2.5 to 3 hours.

QUESTION: 8

The pulsator clarifier is a type of

Solution:

Explanation: The pulsator clarifier is a vertical flow sludge tank in which pulse is generated at interval of 30Sec to give rapid flow for 5-10Sec resulting in the alternative rising up of the sludge blanket.

QUESTION: 9

Which device solved the problem of unstable hydraulic conditions and operation of sludge removal equipment?

Solution:

Explanation: Tube settler solved the problem of unstable hydraulic conditions and operation of sludge removal equipment by providing laminar flow conditions for sedimentation.

QUESTION: 10

In which device, the primary mixing is followed by a secondary reaction zone resulting in formation of sludge blanket?

Solution:

Explanation: In Solid contact clarifier, sludge blanket is formed where straining action occurs to remove some of the finer particles. The thickness of the blanket is 1m.

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