What is COD and how does it differ from BOD?

What is COD and how does it differ from BOD?

• A. COD is the chemical oxygen demand, measuring total oxidizable organics quickly.
• B. BOD measures biodegradable organics over five days, while COD measures non-biodegradable components.
• C. COD is the chemical oxygen demand and it is usually higher than BOD because it includes non-biodegradable organics.
• D. COD measures only inorganic pollutants.

Answer: (C)

COD, or chemical oxygen demand, measures the amount of oxygen needed to chemically oxidize both biodegradable and non-biodegradable organic matter in a sample. BOD, or biochemical oxygen demand, measures the oxygen that microorganisms consume to biologically degrade biodegradable organics over a set period (usually five days). Because the chemical test oxidizes a broader range of organics, including those that microbes can’t easily break down, COD values are typically higher than BOD values for the same sample. This is why COD provides a more complete picture of total oxygen demand, while BOD focuses on the portion of organics that are readily biodegradable and relevant to biological treatment.

COD, or chemical oxygen demand, measures the amount of oxygen needed to chemically oxidize both biodegradable and non-biodegradable organic matter in a sample. BOD, or biochemical oxygen demand, measures the oxygen that microorganisms consume to biologically degrade biodegradable organics over a set period (usually five days). Because the chemical test oxidizes a broader range of organics, including those that microbes can’t easily break down, COD values are typically higher than BOD values for the same sample. This is why COD provides a more complete picture of total oxygen demand, while BOD focuses on the portion of organics that are readily biodegradable and relevant to biological treatment.