What is the typical COD range mentioned for wastewater?

• A. 550-700 mg/L
• B. 100-300 mg/L
• C. 50-150 mg/L
• D. 800-1000 mg/L

Answer: (A)

Chemical Oxygen Demand (COD) measures how much oxygen is needed to chemically oxidize the organic matter in wastewater. For typical municipal wastewater, the influent COD is commonly cited as about 550 to 700 mg/L. This range reflects the average strength of domestic waste, including both readily biodegradable and more stubborn organics that can be oxidized chemically. COD tends to be higher than BOD because it accounts for substances that aren’t readily biodegradable as well as inorganic oxidizable materials, giving a quicker, more inclusive measure of organic load. The other ranges are outside the usual strength you’d expect in ordinary wastewater influent, making 550–700 mg/L the best fit.