Effects of dissolved organic matters and biofilm on disinfection by-products formation potential in tap water

Abstract

This study aims to investigate the effects of biofilm in drinking water distribution system on dissolved organic matter (DOM) consumption and adsorption and to analyze the disinfection by-products formation potential (DBPsFP) which caused by DOM or biofilm and the combination of DOMs and biofilm in treated water distribution system. Also, the objective of this research is to evaluate the adsorption efficiency of occurred DBPs by using granular activated carbon (GAC). The results showed that active and inactivated biofilm has capacity to consume and adsorb mixed DOM, hydrophilic DOM (HPI) and hydrophobic DOM (HPO) fraction. Biological consumption of all kind of DOMs was confirmed by comparing DOM consumption data of active biofilm with abiotic data. For the result of formation potential based on organic carbon content, Haloacetonitriles (HANs), Haloacetic acids (HAAs), and Haloketones (HKs), except Chloroform (CF), have high formation potentials in individual samples of DOM and DOM fractions but started to decrease formation potential in mixed DOM or DOM fractions with biofilm. That might be caused by the consumption of DOM and occurred DBPs (excepted CF) by biofilm’s activities. HANs seem to have high formation potential which calculated based on the amount of dissolved organic nitrogen (DON). From obtained results, the existing of re-growth biofilm in distribution system might reduce DBPsFP of HANs, HAAs and HKs that occurred from the reaction of chlorine and remained DOM. Also, dichloroacetonitrile (DCAN) seems easier to be adsorbed by granular activated carbon (GAC) than CF.