Solid Waste Management MCQ with answer and solution

Concept

Thermal waste-to-energy technologies: Pyrolysis and Plasma Gasification

Formula

C_n H_m O_p -> CO + H2 + CH4 (Syngas generation in thermal dissociation)

Step-by-step solution

1. Evaluate statement (i): Pyrolysis and plasma gasification convert solid wastes into clean syngas and energy; thus, (i) is correct. 2. Evaluate statement (ii): Pyrolysis is thermal decomposition in an oxygen-free environment; plasma gasification uses ionized gas (plasma arc) at extremely high temperatures to break molecular bonds; thus, (ii) is correct. 3. Since both statements are correct, option C is the right answer. Answer: C

Explanation

Both statements are true. (i) Pyrolysis and plasma gasification are advanced thermal waste-to-energy technologies converting municipal solid waste, plastics, and biomass into syngas (CO and H2) and energy products while reducing landfill dependency. (ii) Pyrolysis is thermal degradation occurring strictly in the absence of oxygen (anaerobic, 400–800°C), while plasma gasification utilizes high-energy thermal plasma arcs (3,000–10,000°C) to dissociate waste into elemental gases and vitrified slag.

Why the other options are wrong

A) Incorrect because statement (ii) is also technically accurate. B) Incorrect because statement (i) accurately defines both processes as waste-to-energy technologies. D) Incorrect because both statements are factually sound.

Shortcut

Pyrolysis = Heat without oxygen; Plasma gasification = Ultra-high temp plasma arc; Both = Clean syngas.

Common mistake

Confusing pyrolysis with incineration (which requires excess oxygen) or assuming plasma gasification is not a thermal method.