Wastewater COD fractionation in the biological wastewater treatment
Consists of the total fraction from COD that can be biodegradated by the heterotrophic microorganisms.
Readily biodegradable (rbCOD, SS)
Consists of small molecules that are directly available for biodegradation by heterotrophic microorganisms.
Slowly biodegradable (sbCOD, XS)
Consists of larger molecules requiring extracellular breakdown (hydrolysis) before being biodegradated by the heterotrophic microorganisms.