Aquatic Organic Matter Fluorescence
103
fluorescence was employed because of its specificity in measuring humic substances, aromatic compounds, and heterocyclic systems. Rather than obtaining fluorescence emission
spectra, specific intensities at 490 nm were obtained using a fixed excitation wavelength
of 365 nm. In addition to these fluorescence measurements the UV absorbance at 280 nm
was also measured, and correlated with respective chemical oxygen demand (COD) values.
The COD provides an estimation of the amount of oxidizable material present within the
sample via oxidation with a strong acid (Eaton et al., 2005), and from this the amount of
organic matter removal is estimated. The focus of this study was the removal efficiency
of organic matter as opposed to understanding and interpreting the nature of the observed
fluorescence spectra.
It is now accepted that all wastewaters exhibit characteristic fluorescing properties and this phenomenon was first reported in the mid-1990s. Research undertaken by
Ahmad et al. (1994), Ahmad and Reynolds (1995), and Reynolds and Ahmad (1995)
demonstrated the fluorescence emission spectra of wastewaters using a number of different excitation wavelengths. A typical fluorescence emission spectrum, using an excitation at 280 nm, is shown in Figure 3.12. From these early studies, research concerning
the use of fluorescence as a tool for water treatment process optimization, water quality assessment, and pollution monitoring has emerged (Henderson et al., 2009). Further
developments from this early work facilitated the use of synchronous fluorescence spectroscopy (SFS), which is the simultaneous scanning of both the excitation and emission
wavelengths, and the recording of the distribution of intensities over the emission (or
excitation) wavelengths.
300
0
0.1
0.2
Normalized Fluorescence Intensities
0.3
0.4
340 380
Wavelength (nm)
420 460 500 540
Figure 3.12. Typical fluorescence spectra of untreated (black line) and treated wastewater (gray line)
using 280 nm excitation.
103
fluorescence was employed because of its specificity in measuring humic substances, aromatic compounds, and heterocyclic systems. Rather than obtaining fluorescence emission
spectra, specific intensities at 490 nm were obtained using a fixed excitation wavelength
of 365 nm. In addition to these fluorescence measurements the UV absorbance at 280 nm
was also measured, and correlated with respective chemical oxygen demand (COD) values.
The COD provides an estimation of the amount of oxidizable material present within the
sample via oxidation with a strong acid (Eaton et al., 2005), and from this the amount of
organic matter removal is estimated. The focus of this study was the removal efficiency
of organic matter as opposed to understanding and interpreting the nature of the observed
fluorescence spectra.
It is now accepted that all wastewaters exhibit characteristic fluorescing properties and this phenomenon was first reported in the mid-1990s. Research undertaken by
Ahmad et al. (1994), Ahmad and Reynolds (1995), and Reynolds and Ahmad (1995)
demonstrated the fluorescence emission spectra of wastewaters using a number of different excitation wavelengths. A typical fluorescence emission spectrum, using an excitation at 280 nm, is shown in Figure 3.12. From these early studies, research concerning
the use of fluorescence as a tool for water treatment process optimization, water quality assessment, and pollution monitoring has emerged (Henderson et al., 2009). Further
developments from this early work facilitated the use of synchronous fluorescence spectroscopy (SFS), which is the simultaneous scanning of both the excitation and emission
wavelengths, and the recording of the distribution of intensities over the emission (or
excitation) wavelengths.
300
0
0.1
0.2
Normalized Fluorescence Intensities
0.3
0.4
340 380
Wavelength (nm)
420 460 500 540
Figure 3.12. Typical fluorescence spectra of untreated (black line) and treated wastewater (gray line)
using 280 nm excitation.