Texas Wastewater Class B Practice Exam

During bacterial decomposition of organic materials in wastewater, which gases are primarily produced?

1. Ozone, nitrogen, and hydrogen

2. Hydrogen sulfide, carbon dioxide, and methane

3. Ammonia, sulfur dioxide, and chloramine

4. Methanol, ethylene, and acetylene

The correct answer is: Hydrogen sulfide, carbon dioxide, and methane

The selection of hydrogen sulfide, carbon dioxide, and methane as the primary gases produced during bacterial decomposition of organic materials in wastewater is accurate. This process, which primarily involves anaerobic bacteria, breaks down organic matter in the absence of oxygen, leading to the production of these specific gases. Hydrogen sulfide is notable for its characteristic odor of rotten eggs and is a result of the breakdown of sulfur-containing organic compounds. Carbon dioxide is a common byproduct of respiration and fermentation processes. Methane, which is a significant greenhouse gas, is produced as an end product of the anaerobic digestion of organic matter, particularly in settings like septic tanks and landfills. The other options contain gases that are either not primary products of the bacterial decomposition process or are related to different chemical reactions. For example, ozone is not typically produced in significant quantities during the natural processes of decomposition and is more related to atmospheric or engineered processes. Similarly, ammonia does arise in some instances, but sulfur dioxide and chloramine are not predominantly formed during organic matter decomposition in wastewater. Lastly, the presence of methanol, ethylene, and acetylene would be unusual in this context, as they are not typical gaseous outputs of the decomposition of organic material but rather associated with other chemical processes