→ BOD shows biodegradable pollution → COD shows total pollution

BOD vs COD: Two Numbers That Decide Your Water Treatment Game

If you’ve ever tested wastewater, you already know these two acronyms:

BOD and COD.

They get mentioned together.

But they mean very different things.

Let’s break the confusion.

➤ What They Actually Measure

↳ BOD (Biochemical Oxygen Demand):

How much oxygen bacteria need to biologically break down organic matter over 5 days.

→ It shows how "alive" the pollution is.

↳ COD (Chemical Oxygen Demand):

How much oxygen is needed to chemically oxidize everything → biodegradable and non-biodegradable.

→ It’s faster. Harsher. More complete.

➤ Why Their Ratio Matters

The BOD/COD ratio gives you a sneak peek into how treatable your wastewater is:

→ > 0.5 → Biologically treatable

→ < 0.3 → Tougher stuff. Toxic or resistant. Needs advanced treatment

And always remember:

✔ COD > BOD → because chemistry burns through more than biology ever could.

➤ So What’s the Real Takeaway?

→ BOD shows biodegradable pollution

→ COD shows total pollution