Question

During sewage treatment biogas produced includes

• A. Hydrogen sulphide, Nitrogen, Methane
• B. Methane, Oxygen, Hydrogen sulphide
• C. Methane, Hydrogen sulphide, Carbon dioxide
• D. Hydrogen sulphide, Methane, Sulphur oxide

Answer 1

The Correct Option is C

The question pertains to the composition of biogas produced during sewage treatment. Biogas is a type of biofuel that is naturally produced from the decomposition of organic matter under anaerobic conditions (absence of oxygen). The main components of biogas produced during sewage treatment typically include:

1. Methane (CH₄): This is the primary component of biogas, usually making up about 50-75% of its composition. It is produced by methanogens, which are a group of microorganisms that break down organic matter in the absence of oxygen.
2. Carbon Dioxide (CO₂): This is the secondary component and typically constitutes 25-50% of biogas. It is produced by the decomposition of organic compounds.
3. Hydrogen Sulphide (H₂S): Although present in smaller quantities, hydrogen sulphide is also a key component of biogas produced during sewage treatment. It is responsible for the characteristic foul smell and must often be treated or removed as it can be corrosive.

Given this understanding, let us evaluate the options:

• Option 1 - Hydrogen sulphide, Nitrogen, Methane: While hydrogen sulphide and methane are components of biogas, nitrogen is generally not a significant part of biogas from sewage treatment.
• Option 2 - Methane, Oxygen, Hydrogen sulphide: Oxygen is not present in biogas as it is produced under anaerobic (oxygen-free) conditions.
• Option 3 - Methane, Hydrogen sulphide, Carbon dioxide: This option accurately lists the components typically found in biogas produced during sewage treatment.
• Option 4 - Hydrogen sulphide, Methane, Sulphur oxide: Similar to nitrogen, sulphur oxides are not typically found in biogas from sewage treatment.

Correct Answer: Option 3 - Methane, Hydrogen sulphide, Carbon dioxide

By understanding the biochemical processes involved in sewage treatment and the typical composition of biogas, we can conclude with certainty that Option 3 is correct.