An example of a biodegradable pollutant is?

Step 1: Analyze the question The question asks for a biodegradable pollutant. That means a pollutant that microorganisms (bacteria and fungi) can break down into simpler, harmless substances.

Step 2: The concept

• Biodegradable pollutants are organic wastes that decomposers can break down naturally. Examples are sewage, food waste, animal dung and paper.
• Non-biodegradable pollutants cannot be broken down by microbes, or break down extremely slowly. Examples are plastics, glass, heavy metals (lead, mercury), DDT and polythene bags.

Step 3: Check each option

• A. Plastic: Non-biodegradable. It stays in the environment for hundreds of years.
• B. Sewage: Biodegradable. It is organic waste, and bacteria decompose it (as in septic tanks and treatment plants).
• C. Carbon (II) oxide: A toxic gas from incomplete combustion. It is an air pollutant, not classed as a biodegradable waste.
• D. Hydrogen sulphide: A poisonous gas, also an air pollutant. It is not described as a biodegradable pollutant in this context.

Step 4: Answer The correct option is B. sewage.

Tip: Ask yourself, "Can bacteria eat it?" If the pollutant is organic waste from living things (sewage, food scraps, dung), it is biodegradable. If it is synthetic or a metal (plastic, polythene, lead), it is non-biodegradable. WAEC often pairs sewage with plastic in questions like this.