Basic Wastewater Operator Practice Exam

What typically indicates a decrease in sewage treatment efficiency?

1. Excessive sludge degradation

2. High levels of dissolved oxygen

3. Excessive fecal coliform bacteria count

4. Low concentration of volatile suspended solids

The correct answer is: Excessive fecal coliform bacteria count

A high level of fecal coliform bacteria count is a significant indicator of decreased sewage treatment efficiency. Fecal coliforms are bacteria that originate from the intestinal tracts of warm-blooded animals and are commonly used as indicators of water quality and the presence of contamination from fecal matter. An elevated count of these bacteria suggests that the treatment process is failing to properly remove pathogens and contaminants, indicating a breakdown in the efficiency of the treatment system. In effective sewage treatment, a well-functioning system should minimize or eliminate these bacteria before the treated effluent is released to the environment. Thus, if the counts of fecal coliform bacteria are high, it reflects inadequacies in disinfection processes, sedimentation, or biological treatment, which should be closely monitored and optimized for better treatment outcomes. Other factors, like excessive sludge degradation or low concentration of volatile suspended solids, can present challenges but do not directly correlate with the immediate presence of harmful bacteria. High levels of dissolved oxygen typically indicate that biological processes are functioning well, which contrasts with the issues indicated by high fecal coliform counts.