In the context of solving pollution problems, what is/are the advantage/advantages of bioremediation technique? Select the correct answer using the code given below:

Answer: (c) 1 and 3 only

Natural biodegradation boosted, plus GM microbes; metals can’t be fully treated.

Statement by statement

1. ✓ CORRECT It speeds up the natural breakdown of pollutants by microbes.

2. ✗ WRONG Heavy metals like lead and cadmium cannot be broken down; microbes can only change or trap them. They are not “readily and completely” treated.

3. ✓ CORRECT Engineered microbes can be designed for specific pollutants.

The idea

Bioremediation uses microbes that eat the pollutant. That works for organic pollutants such as oil, sewage and many pesticides: microbes break them down to carbon dioxide and water. A heavy metal is an element. It cannot be broken down into anything; it can only be changed in form, trapped or moved.

Oil spill or contaminated soil → Add nutrients, air or selected microbes → Microbes multiply and feed on the pollutant → Pollutant → carbon dioxide + water → Site is cleaned without digging it up

The trap

“Readily and completely” — two absolute words in statement 2.

Elimination technique

Statement 2 says “any contaminant … readily and completely treated”. Absolute words usually mark the false statement in Environment PYQs. That removes (b) and (d).

Also know

Oilzapper, developed by TERI, is a mix of oil-eating bacteria used on oil spills and oily sludge in India. An oil-eating Pseudomonas made by Ananda Chakrabarty became the first living organism held patentable (US Supreme Court, 1980). Using plants to take up pollutants is called phytoremediation.