Tennessee Wastewater Operator Practice Exam

Which of the following bacteria obtain carbon from BOD?

1. Nitrifying bacteria

2. Autotrophic bacteria

3. Heterotrophic bacteria

4. Denitrifying bacteria

The correct answer is: Heterotrophic bacteria

Heterotrophic bacteria are organisms that obtain their carbon from organic compounds, which includes biochemical oxygen demand (BOD) derived from decomposing organic matter in wastewater. These bacteria play a crucial role in the treatment of wastewater, as they consume organic pollutants, thus reducing the BOD levels in the effluent. In the context of wastewater treatment, understanding that heterotrophic bacteria utilize organic matter is essential. They thrive in environments rich in BOD, breaking down these compounds and converting them into biomass, carbon dioxide, and energy. This process not only helps in reducing the pollution load but is also vital for maintaining the overall balance of the microbial population in treatment systems. Other groups of bacteria, such as nitrifying bacteria, rely on inorganic compounds for their carbon source, while autotrophic bacteria specifically use carbon dioxide to form organic compounds, and denitrifying bacteria primarily convert nitrates to nitrogen gas, with less emphasis on BOD. Recognizing the unique roles that different bacteria play is fundamental in the effective management of wastewater treatment processes.