Differentiating Effluent Organic Matter (EfOM) from Natural Organic Matter (NOM): Impact of EfOM on Drinking Water Sources

In this study, the characteristics of effluent organic matter (EfOM) were investigated and differentiated from natural organic matter (NOM) using several analytical methods: XAD resin fractionation, size-exclusion chromatography in combination with a dissolved organic carbon detector (SEC-DOC), fluorescence spectroscopy (excitation-emission matrix (EEM) and fluorescence index (FI)), biodegradable dissolved organic carbon (BDOC) testing, ultraviolet absorbance at 254 nm (UVA 254 ), and DOC measurements. Also, the impact of EfOM on drinking water sources was evaluated in terms of treatability of the EfOM by a drinking water treatment process. Treatability experiments were carried out with various mixtures of NOM and EfOM by a coagulation process. Characterization results indicated that the distinct properties of EfOM were lower specific UVA (SUVA), more hydrophilic organic matter, increased FI values, higher polysaccharides peak in SEC, and clear protein-like peak in EEM, as compared to NOM. Removal of DOC in EfOM-dominated waters by coagulation was not as high (∼38%) as those of NOM samples (∼57%), which was attributed to the higher hydrophilicity of EfOM. BDOC of EfOM occurred primarily via degradation of microbially derived organic constituents, such as proteins and polysaccharides.