Which among the following is used to remove over 99 per cent particulate matter present in the exhaust from a thermal power plant ?

Electrostatic precipitator

The correct answer is Option (4)- Electrostatic precipitator

There are several ways of removing particulate matter; the most widely used of which is the electrostatic precipitator, which can remove over 99 per cent particulate matter present in the exhaust from a thermal power plant. It has electrode wires that are maintained at several thousand volts, which produce a corona that releases electrons. These electrons attach to dust particles giving them a net negative charge. The collecting plates are grounded and attract the charged dust particles.

A scrubber  can remove gases like sulphur dioxide. In a scrubber, the exhaust is passed through a spray of water or lime.

Hospitals generate hazardous wastes that contain disinfectants and other harmful chemicals, and also pathogenic micro-organisms. Such wastes also require careful treatment and disposal. The use of incinerators is crucial to disposal of hospital waste.

A bioreactor is a large vessel used to produce a substantial volume of culture. In a bioreactor, various cells such as human, plant, or animal cells can be cultured to generate new biological products.