Wastewater Lab · COD Introduction
What Is COD, and How Is It Different From BOD?
COD is a chemical oxygen-demand measure; BOD is a biological oxygen-use test, and the two are not interchangeable.
What COD Represents
Chemical oxygen demand uses a chemical reaction to estimate the oxygen needed to oxidize substances in the sample. It does not identify each compound or directly measure oxygen use in the treatment basin.
Why It Can Be Useful
COD results are available much sooner than five-day BOD results, so they can help operators watch loading or process trends. Keep each result tied to the sample location, time, and plant condition.
COD Is Not BOD
BOD measures biological oxygen use during its test period. COD uses chemical oxidation. Because they measure different things, their values are not interchangeable.
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Laboratory Fundamentals
This page comes from the free course. It follows a wastewater sample from collection to a result an operator can use, with short knowledge checks and a certificate of completion.
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