Characterization of Sewage Effluent in Natural Waters Using Fluorescence Techniques
Abstract Sewage is treated and released into the Grand River by the communities along it. It is expected that progression down the river would show increasing relative concentrations of the chemical components of sewage effluent. Previous research has shown that two of these components, tyrosine and tryptophan, are detectable using fluorescence spectroscopy. To determine if the relative amounts of tyrosine and tryptophan are increasing, decreasing, or remaining steady, samples are taken at five spots within the sampling site. The chosen sampling site contains a stream of sewage effluent released directly from the wastewater treatment plant, which runs into the Grand River. This sampling site is ideal, as it allows sampling of the sewage effluent directly from the wastewater treatment plant, and sampling both upstream and downstream of the input point, as well as sampling between September 206, and March 2007. The fluorescence of these samples is then measured, and fluorescence excitation-emission matrices (FEEM s) are produced. These FEEM s are used to resolve the spectra into components contributing to fluorescence using Matlab and PARAFAC. To normalize the results, dissolved organic carbon (DOC) was measured; DOC is a quantitative measurement of dissolved organic matter (DOM), some of which is responsible for fluorescence of natural waters. The results indicate that tyrosine and tryptophan are easily detected using FEEM s, and that using the DOC values to normalize the results, both spatial and temporal trends are observed within the data. These trends show that the relative concentrations of tyrosine and tryptophan are decreasing as progression down the river occurs. The use of fluorescence spectroscopy is a rapid and selective technique that could easily be used for environmental monitoring of wastewater release.
Examining Aluminum and Iron Hydrolysis Species for Coagulants in Water Treatment
Abstract Part of the normal water treatment process involves coagulation and flocculation to remove organic matter and phosphate in water. Aluminum or iron can be used as coagulants in water treatment to bind to the organic matter and phosphate to prepare it for flocculation followed by filtration. Polynuclear aluminum species are used by some companies instead of the traditional alum (Al2(SO4)3 18H2O) for drinking water treatment due to the higher charge neutralization capacity. The polynuclear aluminum coagulants of interest are Al13 7+ and Al30 18+. By studying aluminum hydrolysis the synthesis of these species can be optimized and quantified for their use in water treatment. Iron hydrolysis is also studied to better understand its role in removing phosphate by adsorption. From observed changes in UV-Vis absorbance spectra for different pH values a better understanding of aluminum and iron hydrolysis species was gained. Synthesizing polynuclear aluminum species raised questions about the generally agreed upon method of synthesis. Many parameters (mixing rate, base addition rate, aging, and heating for example) need to be considered and are poorly reported in others work. Moreover, the synthesis of Al13 and Al30 does not yield a perfectly clear solution to make absorbance readings of. Due to a lacking trend in changing aluminum spectra and a high level of noise interfering with any signatures at low wavelengths, a distribution diagram for aluminum could not be created. As a result no species or concentrations were identified except a potential signal for Al30 near 300nm. Iron speciation analysis was more successful with the use of an in-situ probe and salt corrected absorbance. As a result, distinct peaks in the absorbance spectra, relating to various iron species could be identified. Species for Fe3+, FeOH2+, FeOH2 + and FeOH4 - were identified by analyzing absorbance spectra with SIMPLSIMA.
Copper binding to model tripeptides in blood using multiresponse speciation techniques
Speciation refers to the distribution of the total element among its possible chemical forms in the system. It gives insight into the mechanism of uptake and whether or not the metal is toxic, biologically available or unavailable. The metal studied is copper (II) and the ligands that will form the metal-complexes are tripeptides. The tripeptides studied are Ala-Ala-Ala, Ala-Gly-Gly, and Gly-Gly-Ala. The objective of this experiment is to validate a new proposed multiresponse technique in metal speciation. This was done by obtaining and processing results which were compared to a previous study where a similar multiresponse technique was carried out by Gyrucsik et al, 2001. Their study involved instruments such as CD spectroscopy, potentiometry, and spectrophotometry but they did not utilize multiresponse statistics. This new proposed technique involves the use of an ion-selective electrode, pH electrode, and UV/Vis spectrophotometry in a titration where the pH was varied while the metal and ligand concentrations were fixed in a 1:1 stoichiometric ratio. Several trials were completed for each ligand and the results were graphed and they showed that the data obtained was reproducible. Equilibrium modelling was then carried out for method validation by comparing experimental results to theoretical values obtained by Gyrucsik et al, 2001. Equilibrium modelling consisted of comparing: the experimental and theoretical free copper; experimental and theoretical b calculation; experimental species absorbencies to theoretical species concentrations, as determined by the equilibrium model for quantitative and qualitative analysis. This method was successfully validated and can now be used to assess metal toxicity in biological systems such as copper (II) toxicity in blood.