Principles and Practice of Engineering (PE) Civil: Water Resources and Environmental (WRE) Practice Exam

Microorganisms play a crucial role in the decomposition of organic matter in wastewater treatment, and each type has its specific functions. Bacteria, fungi, and protozoa are actively involved in this process.

Bacteria are the primary decomposers in wastewater treatment. They break down organic matter by utilizing it as a food source, resulting in the conversion of complex compounds into simpler substances. This process is essential for reducing the biochemical oxygen demand (BOD) of wastewater, making it less harmful before being released back into the environment.

Fungi contribute to decomposition by breaking down complex organic materials, particularly lignocellulosic matter. They are instrumental in nutrient cycling and are known for their ability to degrade tough plant materials, which enhances the overall process of organic matter breakdown.

Protozoa play a supportive role in wastewater treatment by consuming bacteria and other small organic particles. This predation helps regulate bacterial populations and contributes to the stabilization of organic matter in the treatment process.

In contrast, viruses are not involved in the decomposition of organic matter. They are pathogenic entities that can infect and replicate within host cells but do not contribute to the breakdown of organic substances. Therefore, identifying viruses as the microorganism not involved in the decomposition process highlights their distinct role compared to