Biogas MCQs Quiz | Class 9

This quiz is for Class 9 students studying Home Science (Code 064), Unit VI: Resource Management. It covers key concepts related to biogas, including the basic concept, the process of converting kitchen waste to gas, and the various benefits of biogas. Attempt all questions, submit your answers to see your score, and download the PDF answer sheet for review.

Understanding Biogas: From Waste to Energy

Biogas is a renewable source of energy produced from the breakdown of organic matter in the absence of oxygen. This process, known as anaerobic digestion, is a natural way to convert waste materials like kitchen scraps, animal manure, and agricultural waste into a valuable fuel. For Home Science students, understanding biogas is crucial as it represents a sustainable method of resource management within the home and community.

Key Concepts of Biogas Production

1. The Concept of Biogas

Biogas is a mixture of gases, primarily composed of methane (CH4, about 50-75%) and carbon dioxide (CO2, about 25-50%), with trace amounts of other gases. Methane is the component that makes biogas flammable, allowing it to be used for cooking, heating, and generating electricity. Because it is produced from organic waste, it is considered a clean and renewable fuel.

2. The Process: Kitchen Waste to Gas

The conversion of organic waste into biogas happens in a sealed container called a digester. The process involves four key stages carried out by different types of microorganisms:

  • Hydrolysis: Complex organic materials like carbohydrates and proteins are broken down into simpler molecules like sugars and amino acids.
  • Acidogenesis: Bacteria convert these simple molecules into organic acids.
  • Acetogenesis: Other bacteria convert the organic acids into acetic acid, hydrogen, and carbon dioxide.
  • Methanogenesis: Methane-producing microorganisms (methanogens) convert these final products into methane gas.

Kitchen waste, such as vegetable peels, leftover food, and spoiled fruits, is an excellent feedstock for a small-scale, household biogas plant.

3. Benefits of Biogas

The use of biogas technology has numerous advantages that span environmental, economic, and health sectors.

Benefit Type Description
Environmental Reduces greenhouse gas emissions by capturing methane that would otherwise be released from decomposing waste. It also reduces landfill waste and protects water bodies from waste contamination.
Economic Provides a free or low-cost source of fuel, reducing reliance on expensive fossil fuels like LPG. The nutrient-rich residue (slurry) from the digester can be used as an excellent organic fertilizer, improving soil health and crop yields.
Health & Sanitation Improves sanitation by properly managing organic waste. Using biogas for cooking reduces indoor air pollution from burning wood or coal, preventing respiratory diseases.

Quick Revision Points

  • Biogas is mainly a mixture of methane and carbon dioxide.
  • The process of biogas production is called anaerobic digestion (without oxygen).
  • Organic waste like kitchen scraps, animal dung, and farm waste are used as raw materials.
    • – The sealed container where the process occurs is called a digester.
  • The solid residue left after digestion is a valuable organic fertilizer called slurry or digestate.
  • Biogas is a renewable and clean energy source with significant environmental benefits.

Practice Questions

  1. What is the main flammable component of biogas?
  2. Name the four stages of anaerobic digestion.
  3. Why is biogas considered a renewable energy source?
  4. What is the name of the residue left after biogas production and what is its primary use?
  5. List two environmental benefits of installing a biogas plant at home.