Abstract:
This study aimed to assess the coagulation performance using simple aluminum sulfate (Alum) and pre-hydrolyzed polyaluminum
chloride (PACl) coagulation agents by conventional global parameters, i.e., turbidity and organic matter expressed by total
organic carbon (TOC) and chemical oxygen demand (COD), and non-conventional spectrophotometric parameters.
Non-conventional spectrophotometric parameters, expressed as absorbance recorded at different wavelengths, i.e., A254, A280,
A365, allowed distinguishing some components classes with different degrees of activation, which are parts of natural organic
matter (NOM) from drinking water. Monitoring the A254/A280 ratio in coagulation stage allowed determining the removal
efficiency of some undesirable humic compounds with increased activity, which exhibited the trihalomethanes (THMs) formation
potential during disinfection stage. Monitoring the A254/A365 ratio in coagulation stage allowed determining the removal
efficiency of some undesirable humic compounds with hydrophobic character. All experimental results showed that the specific
absorbance (SUVA) parameter expressed as the ratio between A254 and dissolved organic carbon (DOC), can be used
successfully to characterize NOM from raw water and predicts DOC removal in coagulation step. The correlation between
conventional and non-conventional parameters showed a better performance of coagulation performance using PACl in
comparison with Alum coagulation agent.