Tennessee Wastewater Operator Practice Exam

Facultative ponds are capable of processing more BOD when?

1. Wastewater is colder

2. Wastewater is warmer

3. There is less sunlight

4. There is higher salinity

The correct answer is: Wastewater is warmer

Facultative ponds are designed to treat wastewater using both aerobic and anaerobic processes. They have a layer of aerobic bacteria at the surface, which requires sunlight and warmth to thrive. When the temperature of the wastewater is warmer, it enhances the microbial activity, increasing their metabolic rates. This leads to improved breakdown of biochemical oxygen demand (BOD), resulting in more efficient treatment of the wastewater. Warmer temperatures also promote the growth of algae, which plays a crucial role in the processes occurring in facultative ponds. Algae contribute oxygen to the water during photosynthesis, which supports aerobic organisms that further assist in BOD reduction. Thus, warmer wastewater conditions lead to a more active microbial population, increasing the pond's capacity to process BOD effectively. In contrast, colder wastewater can slow down microbial metabolism, resulting in less efficient BOD processing. Reduced sunlight would decrease algal activity and, consequently, the oxygen available for aerobic bacteria. Higher salinity might affect microbial populations negatively, hindering their effectiveness in treating wastewater. Therefore, warmer wastewater conditions facilitate the optimal functioning of facultative ponds for BOD processing.