Texas Wastewater Class B Practice Exam

What do offensive and objectionable odors in trickling filters usually indicate?

1. Normal operational conditions

2. Septic conditions are present

3. High levels of dissolved oxygen

4. Excessive algae growth

The correct answer is: Septic conditions are present

Offensive and objectionable odors in trickling filters typically indicate the presence of septic conditions. This occurs when the biological processes within the filter are not functioning optimally. Under normal circumstances, trickling filters are expected to facilitate aerobic conditions where microorganisms break down organic material, resulting in minimal odor production. However, when septic conditions arise, it often means that there is a lack of adequate oxygen for the aerobic bacteria, leading to anaerobic processes that produce foul-smelling compounds such as hydrogen sulfide. This shift from aerobic to anaerobic conditions is a primary reason why strong odors are noticed, making identifying septic conditions crucial for addressing potential operational issues in the wastewater treatment process.