AWWA WQTC62564

Natural organic matter (NOM) reactivity for disinfection byproduct (DBP) formation wasinvestigated in this study. Two surface waters (Hillsborough River and Quabbin Reservoir) withsignificantly different SUVA and dissolved organic carbon (DOC) were fractionated using an isolation protocol whichcombines vacuum evaporation and ultrafiltration before adsorption onto non-ionic XAD-8 resin.Three pools of NOM were isolated: high molecular weight fraction (HMW, >3KDa); hydrophobic fraction (HPO, <3 KDa); and, hydrophilic fraction (HPI, <3KDa). It was foundthat neither ultrafiltration (UF) nor sorption/desorption to XAD-8 resin altered reactive sites within the NOMthat were responsible for DBP formation as demonstrated by similar DBP formation fromunfractionated raw water and the reconstituted water from NOM fractions before freeze drying.Freeze drying changed the chemical structure of NOM and its reactivity for haloacetic acid (HAA) formation asdemonstrated by a significant difference in DBP formation from unfractionated raw water andthe reconstituted water from NOM fractions after freeze drying. An increase in DBP formationfor each individual NOM fraction was noted across freeze drying. In addition, the contribution ofeach fraction (before or after freeze drying) to total DBP formation appears to be additive withno synergistic effects among NOM fractions. The evaporation step during isolation protocolseems to have an influence on Trihalomethane (THM) formation as demonstrated by a decrease of THM yield ofthe source water calculated by summing the contribution of each NOM fractions before freezedrying compared to the yield of the unfractionated water.It was found that high molecular weight (HMW) fractions of high SUVA water (HillsboroughRiver) led to higher THM4 and HAA9 yields than the corresponding low molecular weightfractions (HPI and HPO). For low SUVA water (Quabbin Reservoir) low molecular weightfractions (HPI and HPO) exhibited high THM4 and HAA9 yields than the corresponding HMWfraction. These results suggest that chemical composition and origin of NOM is more valuablefor predicting DBP formation than molecular weight. THM yield from the hydrophilic fractionwas consistently higher than its formation from the hydrophobic fraction. Hydrophobic fractions,which are rich in aromatic content, phenolic hydroxyl groups and conjugated double bonds, gavehigher HAA formation potential than hydrophilic fractions. Includes 18 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2005

Number of Pages:

18

File Size:

1 file , 820 KB