Influence of pre-treatments and recycled flows on the COD fractions of a wastewater: a case study .

Discusses how physical-chemical and biological fractionation methods were used at different parts of the Evry WWTP in order to assess the influence of effluents recycled from the primary settling tanks and sludge treatment processes on the characteristics of the wastewater. Consideration of the primary sludge gravity thickener effluent; Findings that significant variations of RBCOD across the plant were not caused by fluctuations of the physical-chemical COD fractions.