By Heather Jennings, PE
When I first came into the water field in the 2000s, the general rule of Chemical Oxygen Demand to Biochemical Oxygen Demand (or COD to BOD5) was 2:1. That was pretty much all you needed to know in order to understand whether something could be treated chemically, physically, or biologically. Now, the wastewater industry has moved toward COD instead of BOD5. The reason that COD is sometimes preferred is that BOD5 doesn’t take into account the organics that become biomass nor the non-biodegradable carbonaceous matter. COD can also be evaluated in the field with simple test kits, whereas most operators must send their BOD5 tests to third-party labs and wait weeks for results. [Read more…]
