Question

Which of the following gas is produced from landfill wastes?

• A. Biogas
• B. Compressed Natural gas
• C. Liquified petroleum gas
• D. Both Liquified petroleum gas and Compressed Natural gas

Hint:

(c) \textbf{Landfill gas (LFG)} is produced by the anaerobic decomposition of organic waste in landfills.
(d) LFG is a type of \textbf{Biogas}.
(e) Main components: Methane (CH$_4$) and Carbon Dioxide (CO$_2$).
(f) Natural Gas (source of CNG) is primarily methane from fossil deposits. LPG is propane/butane from petroleum/natural gas processing.

Answer 1

The Correct Option is A

Analysis of Landfill Gas and Biogas: 

Landfill waste, especially organic waste such as food scraps, paper, and yard trimmings, undergoes anaerobic decomposition by microorganisms in the absence of oxygen. This process produces landfill gas (LFG), which consists primarily of methane (CH₄) and carbon dioxide (CO₂). A smaller percentage of other gases like nitrogen (N₂), oxygen (O₂), hydrogen sulfide (H₂S), ammonia (NH₃), and various volatile organic compounds (VOCs) may also be present. Let’s evaluate the options based on the characteristics of landfill gas:

• Option (a): Biogas

This is the general term for the gas produced from the anaerobic decomposition of organic matter. Landfill gas (LFG) is a type of biogas, as it is generated through the same process of anaerobic digestion. Therefore, landfill gas is accurately described as biogas, and this is the correct answer.

• Option (b): Compressed Natural Gas (CNG)

CNG is primarily composed of methane (CH₄) extracted from geological deposits. While landfill gas does contain methane, it is not considered "natural gas" since it originates from organic waste rather than fossil fuels. Moreover, landfill gas typically requires upgrading to remove CO₂ and impurities before it can be used as CNG. Thus, this is not the correct answer.

• Option (c): Liquefied Petroleum Gas (LPG)

LPG is composed mainly of propane (C₃H₈) and butane (C₄H₁₀) and is a byproduct of petroleum refining and natural gas processing. It is not produced from landfill waste, making this option incorrect.

• Option (d): Both Liquefied Petroleum Gas and Compressed Natural Gas

As discussed, LPG is not produced from landfill waste, and while landfill gas contains methane, it is distinct from natural gas. Therefore, this combined option is incorrect.

Conclusion:

The correct answer is: Option (a) Biogas, as landfill gas is a type of biogas produced from the anaerobic decomposition of organic matter.

Answer:

Biogas