Normalization of wastewater coagulation-flocculation trials and implications in terms of variability in treatment performance and comparison of commercial coagulants.

Normalizations by TSS or P-PO initial concentrations are consistent as they are correlated to the Jar-test performances. Jar-tests results are independent of the wastewater quality variations in terms of TSS and P-PO and independent of the WWTP origin of the water. A notable variability in the TSS results indicates that the pollutant's initial load has to be taken into account even with normalizations.

International cross-validation of a BOD5 surrogate.

BOD5 dates back to 1912 when the Royal Commission decided to use the mean residence time of water in the rivers of England, 5 days, as a standard to measure the biochemical oxygen demand. Initially designed to protect the quality of river waters from extensive sewage discharge, the use of BOD5 has been quickly extended to waste water treatment plants (WWTPs) to monitor their efficiency on a daily basis. The measurement has been automatized but remains a tedious, time- and resource-consuming analysis.