Spectroscopic and elemental investigation of microbial decomposition of aquatic fulvic acid in biological process of drinking water treatment

As humic substances left in treated water tend to form trihalomethans during chlorination, their removal in water treatment processes is a significant concern for drinking water supplies. One of the removal technologies, the biofilm reactor is studied for the microbial decomposition of aquatic fulvic acid (AFA). The AFA is characterized by elemental analysis, UV-Vis, ¹³C-NMR, and IR spectroscopic methods. The spectroscopic and elemental investigation was capable of characterizing the microbial decomposition of AFA. Biologically treated fulvic acid was in a more oxidized state; its spectra displayed a higher degree of condensation of aromatic constituents than influent fulvic acid. Microbial degradation of AFA was more active in the low molecular weight fractions and intensively occurred in the aliphatic fraction.Abbreviations A the absorbance at wavelength - specific absorptivities - AFAs aquatic fulvic acids - AHS aquatic humic substances - COD chemical oxygen demand - Da dalton - DO dissolved oxygen - E₄/E₆ratio a ratio between absorbance at 465 and 665 nm - FA fulvic acid - IR infrared - NMR nuclear magnetic resonance - TOC total organic carbon - UV-Vis ultraviolet-visible