Which equation correctly defines the relationship between NOD and BOD?

The relationship between NOD (Nitrogenous Oxygen Demand) and BOD (Biochemical Oxygen Demand) is represented by the equation NOD = BOD - CBOD (Carbonaceous Biochemical Oxygen Demand). In this equation, BOD represents the total oxygen demand exerted by both carbonaceous and nitrogenous materials in the wastewater. CBOD specifically accounts for the oxygen demand related to carbonaceous materials only.

By subtracting CBOD from BOD, you isolate the nitrogenous component of the oxygen demand, which is what NOD represents. This distinction is crucial in wastewater treatment, as it helps in understanding the contributions of different types of organic matter to the overall oxygen demand, aiding in effective treatment process design and implementation.

Other forms, like multiplication or division with BOD and CBOD, would not accurately reflect the physiological characteristics and numerical relationship between these oxygen demand metrics in wastewater analysis. Understanding this relationship is vital for proper assessment of water quality and the efficiency of treatment processes.