CBOD is defined as the portion of oxygen demand required to remove carbon.

• A. BOD
• B. Biosolids
• C. CBOD
• D. Chlorination

Answer: (C)

Carbonaceous oxygen demand is the portion of biological oxygen demand that comes from oxidizing carbon-containing compounds. In wastewater testing, the total BOD reflects both carbon-related oxidation and nitrogen-related oxidation (from ammonia). To isolate the carbon portion, nitrification is inhibited so the oxygen consumed represents carbon oxidation only. That’s why this term is the best fit: it specifically names the part of oxygen demand tied to carbon, whereas the total BOD covers both carbon and nitrogen effects, biosolids are solids, and chlorination is a disinfection step.