Natural organic matter (NOM) reactivity for disinfection byproduct (DBP) formation was
investigated in this study. Two surface waters (Hillsborough River and Quabbin Reservoir) with
significantly different SUVA and dissolved organic carbon (DOC) were fractionated using an isolation protocol which
combines 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 found
that neither ultrafiltration (UF) nor sorption/desorption to XAD-8 resin altered reactive sites within the NOM
that were responsible for DBP formation as demonstrated by similar DBP formation from
unfractionated 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 as
demonstrated by a significant difference in DBP formation from unfractionated raw water and
the reconstituted water from NOM fractions after freeze drying. An increase in DBP formation
for each individual NOM fraction was noted across freeze drying. In addition, the contribution of
each fraction (before or after freeze drying) to total DBP formation appears to be additive with
no synergistic effects among NOM fractions. The evaporation step during isolation protocol
seems to have an influence on Trihalomethane (THM) formation as demonstrated by a decrease of THM yield of
the source water calculated by summing the contribution of each NOM fractions before freeze
drying compared to the yield of the unfractionated water.
It was found that high molecular weight (HMW) fractions of high SUVA water (Hillsborough
River) led to higher THM4 and HAA9 yields than the corresponding low molecular weight
fractions (HPI and HPO). For low SUVA water (Quabbin Reservoir) low molecular weight
fractions (HPI and HPO) exhibited high THM4 and HAA9 yields than the corresponding HMW
fraction. These results suggest that chemical composition and origin of NOM is more valuable
for predicting DBP formation than molecular weight. THM yield from the hydrophilic fraction
was consistently higher than its formation from the hydrophobic fraction. Hydrophobic fractions,
which are rich in aromatic content, phenolic hydroxyl groups and conjugated double bonds, gave
higher HAA formation potential than hydrophilic fractions. Includes 18 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 820 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 18 |
| Published : | 11/01/2005 |
