Fluorescence dissolved organic matter in polluted raw water source: Fractionation and compound identification using PARAFAC

Chromophoric Dissolved Organic Matter (CDOM) in raw water is complex and heterogeneous. Their presence in polluted raw water source disturbs the process of drinking water treatment. Identification of DOM compounds can be conducted by measuring the Fluorescence Dissolved Organic Matter (FDOM) parameters and DOM fractions. This study aims to identify FDOM compounds in polluted raw water source using PARAFAC analysis based on their fractions. DOM fractions such as hydrophilic (Hi), hydrophobic (Ho), and transphilic (Hs) were determined by resin adsorption technique. CDOM characteristic and FDOM compounds were identified in both unfractioned (mixed) and fractioned samples. The PARAFAC identified three major FDOM compounds: tryptophan (C1), unknown compound (C2), and humic (C3). The C1 compound accounted for 71% of the total identified compounds, indicated the raw water source has been polluted by human-made activities. The most dominant compounds in the mixed (M) samples were tryptophan and unknown samples. In the fractionated samples, the main compounds identified in each fraction were humic in hydrophobic (Hs), tryptophan compound in hydrophilic, and tryptophan in transphilic fractions. The unfractioned or mixed water samples predominantly contained aromatic organic compound which sourced from the terrestrial as indicated by the measured UV₂₅₄ (0.24cm⁻¹) and UV₃₅₅ (0.08cm⁻¹). The average UV₂₅₄ measured in Ho and Hi fractions were similar (0.10cm⁻¹), meanwhile the measured UV₃₅₅ in the Ho was 0.03cm⁻¹, and in Hi fraction was 0.02cm⁻¹. The quantity of both CDOM parameters in the Hs fraction was the smallest.