Abstract
This study aimed to compare the removal rates of precursors of disinfection byproducts (DBPs) by ferrihydrite (FH) and powdered activated carbon (PAC) in the hybrid adsorption-microfiltration (MF) processes. The formation potentials of trihalomethanes and haloacetonitriles (DBPFPs) and characteristics of dissolved organic matter (DOM) from drinking water sources having different contents of aromatic DOM and bromide, were evaluated before and after the FH+MF or PAC+MF treatments. It was found that the DOM characteristics influenced significantly on their removal rates; namely, the FH+MF process lowered DBPFP in waters containing aromatic DOM by mainly removing precursors of chlorinated DBPs, whereas brominated DBPs increased after FH+MF due to higher Br/DOC ratios caused by residual bromide. The PAC+MF process was more effective than the FH+MF process in removal of low molecular weight (MW) hydrophilic DOM, which was a precursor of dichloroacetonitrile. In addition to DOM characteristic (i.e. MW, aromaticity), an inorganic precursor (i.e. bromide) also had significant effects on DBP yields and bromine substitution. When bromide was abundant in water, bromine appeared to be more effectively incorporated into low UV-absorbing (i.e. less aromatic) DOM fractions and simple structural DBPs.
