used UV–Visible absorbance to measure hemoglobin at
the inlet of two wastewater treatment plants (WWTPs) processing
slaughterhouse wastewater and reported high intraday variations
in blood concentration. Previous studies related fluorescence to Biological Oxygen Demand (BOD) and COD in urban WWTP and surface water. However, to the best of the authors’ knowledge, there are
no data regarding the use of absorbance combined with fluorescence
to monitor an activated sludge reactor processing slaughterhouse
wastewater.