The correct answer is D. All the above.
During the purification process of sewage, a variety of gases are given off, including carbon dioxide, hydrogen, and ammonia. These gases are produced as a result of the decomposition of organic matter in the sewage. The decomposition process is carried out by a variety of microorganisms, including bacteria and fungi. These microorganisms break down the organic matter into simpler compounds, which are then used as food. As a byproduct of this process, the microorganisms produce gases, including carbon dioxide, hydrogen, and ammonia.
Carbon dioxide is a colorless, odorless gas that is produced when organic matter is broken down. It is a major component of the Earth’s atmosphere and is essential for plant growth. Hydrogen is a colorless, odorless gas that is also produced when organic matter is broken down. It is a flammable gas and is used in a variety of industrial processes. Ammonia is a colorless, pungent gas that is produced when organic matter is broken down. It is a common fertilizer and is also used in a variety of industrial processes.
The gases produced during the purification process of sewage can be harmful to human health if they are inhaled in high concentrations. They can also cause environmental problems, such as air pollution and water pollution. Therefore, it is important to control the release of these gases into the environment. This can be done by using a variety of methods, such as using aeration systems to remove the gases from the sewage, or by using filters to trap the gases before they are released into the environment.