Q6 of 55 Page 118

How does an electrostatic precipitator work?

i) Electrostatic precipitator is a device which is used to extract the suspended dust particles from the gas.
It uses high voltage charge to collect particles on the charged plates.


ii) It has electrode wires which are maintained at high voltages. This produces corona which releases electron.


iii) These electrons get attached to the dust particles, giving them a net negative charge.


iv) The collecting plates collect the negatively charged dust particles.


v) The velocity of air between plates is kept low to allow the dust particles to fall and settle down.


vi) Electrostatic precipitator can remove over 99% particulate matter present in the exhaust from a thermal power plant.


More from this chapter

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3

Water logging and soil salinity are some of the problems that have come in the wake of the Green Revolution. Discuss their causes and adverse effects to the environment.

 4

What are multipurpose trees? Give the botanical and local names of any two multipurpose trees known to you and list their uses.

 5

What are the basic characteristics of a modern landfil site. List any three and also mention the reasons for their use.

Ans. Characteristics of a modern landfil include:


i. methods to contain leachate such as lining clay or plastic liners.


iii. compaction and covering of the waste to prevent it from being blown by wind.


iv. installation of a landfill gas extraction system to extract the gas for use in generation of power


 7

Observe figure and answer the following questions.


i. What ecological term is used to describe the DDT accumulation at different trophic levels?


ii. List any one effect of DDT accumulation on birds


iii. Will DDT accumulation lead to eutrophication?


iv. Does it affect the BOD?


v. Name disease caused by accumulation of any heavy metal.