Geoscience Reference
In-Depth Information
contributes to the formation of disinfection by-products (DBP), and therefore affects how
water treatment facilities are optimized. The potential for DOM in drinking water sources
to generate DBPs was investigated by Marhaba et al. (
2009
). Researchers were able to
predict trihalomethanes formation potential by applying a principal component regression
model to dimensionally reduced spectral fluorescent signatures. Beggs et al. (2009) studied
the relationships between fluorescence intensities (total fluorescence intensities and fluo-
rescence indexes), redox index, chlorine demand, and DBP formation during chlorination.
This study used a PARAFAC model to extract 13 components (fluorophores or groups
of fluorophores) from fluorescence EEMs. Quinone-like components were found to be
strongly correlated to DBP formation. Johnstone and Miller (
2009
) investigated the corre-
lation of water quality characteristics of Iowa River water and associated isolated fractions
to the formation of DBP, specifically trihalomethanes and haloacetic acids, subsequent to
chlorination using multifactor linear regression. In this work, defined regions within fluo-
rescence EEMs were identified using fluorescence regional integration (Chen et al.,
2003
)
and the changes in the fluorescence intensities of these identified regions, in conjunction
with chlorine consumption, were reported to correlate to the formation of specific DBPs.
This work was further developed in a study in which a three component PARAFAC model
was used to assess drinking water DBP formation (Johnstone et al.,
2009
). This PARAFC
model correlated with DOC, chlorine consumption, and individual DBP formation poten-
tial. Interestingly, the multifactor linear regression of selected component scores showed
linear relationships to individual DBPs. According to the researchers, the specificity of this
approach makes the prediction of DBP formation (DBP formation potential) possible.
A recent review by Henderson et al. (
2009
) concludes that the sensitive detection of
contamination events in recycled water systems may be achieved by monitoring peak T
and/or peak C fluorescence. Hambly et al. (
2010
) also examined the application of fluo-
rescence spectroscopy as a monitoring tool in recycled water treatment plants and dual
(recycled and drinking water) distribution systems. This work detected a 10-fold diffe-
rence in the mean fluorescence intensities observed for recycled water compared to drink-
ing water, and concluded that fluorescence could be used for detecting cross connection.
Bieroza et al. (
2009a
,
2009b
,
2010
) used an EEM technique for the assessment of TOC
removal efficiency. Organic matter characterization of water samples was obtained for 16
UK surface water treatment works, and the fluorescence intensity of peak C was found to
be a sensitive and reliable measure of OM content, providing both spatial and temporal
variations (Bieroza et al.,
2009a
). Variations in EEMs were reported for samples from dif-
ferent sites, highlighting the importance of the nature of DOM present. Figure 3.16 shows
EEMs for raw surface water and clarified surface water obtained from the same site. The
same researchers (Bieroza et al.,
2011a
) also reported the use of fluorescence spectroscopy
as a tool to assess the effect of changing coagulation pH on OM removal, character, and
composition.
There is a great deal of interest in the application of fluorescence techniques for the
monitoring of DOM in drinking water and drinking water treatment systems. Early
research dealt with the influence of chlorination and oxidation of NOM and the prediction
