Tracking seasonal changes of natural organic matter in a water treatment plant in Bangkok using EEM-PARAFAC approach

This study aims to evaluate spatial and seasonal changes in natural organic matter (NOM) in Bangkhen Water Treatment Plant, Thailand. Water samples were analyzed for UV absorbance at 254 nm (UV254), dissolved organic carbon (DOC), and fluorescence excitation−emission matrix (EEM) with parallel factor analysis (PARAFAC). DOC concentrations of the raw water in wet and dry seasons were in the range of 4.01-5.75 and 2.34-4.97 mg-C/L, respectively. Fluorescence character of the water samples could be represented by five PARAFAC components, including terrestrial humic-like (C1 and C2), microbial humic-like (C3), microbial protein-like (C4), and fulvic-like (C5) components. Component C2 significantly correlated to DOC and UV254 (R2=0.73-0.88, p<0.01). Coagulation had preferential removal for humic-like materials (C1 and C2). Overall, the results demonstrate that tracking NOM using EEM was more sensitive than UV254 or DOC, which benefits WTP in term of adjusting their processes for better water supply quality.