Environmental Fate and Transport of Sulfolane & Thiolane at Willawong Waste Disposal Site, Brisbane, Australia

Swain, Gregory. (2003). Environmental Fate and Transport of Sulfolane & Thiolane at Willawong Waste Disposal Site, Brisbane, Australia PhD Thesis, School of Engineering, The University of Queensland.

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Author Swain, Gregory.
Thesis Title Environmental Fate and Transport of Sulfolane & Thiolane at Willawong Waste Disposal Site, Brisbane, Australia
School, Centre or Institute School of Engineering
Institution The University of Queensland
Publication date 2003
Thesis type PhD Thesis
Supervisor Bill Clarke
David Lockington
Total pages 174
Collection year 2003
Language eng
Subjects L
760200 Environmental and Resource Evaluation
290700 Resources Engineering
Formatted abstract
This thesis examines the mechanisms affecting the transport of two thiophene compounds, sulfolane (tetrahydrothiophene-1,1-dioxide) and thiolane (tetrahydrothiophene) through groundwater and the vadose zone. Sulfolane and thiolane have been identified in groundwater samples collected from the south-western comer of the Willawong Waste Disposal Site (WDS), Brisbane, Australia. The Willawong WDS was used for the disposal of industrial and municipal wastes and is currently subject to a $A 40 million remediation project. Disposal records show that significant volumes of sulfolane containing waste were disposed in the south-western comer of the site however no records of thiolane disposal activities have ever been found. Sulfolane is completely miscible with water while whilst thiolane is moderately soluble in water and semi-volatile with an unpleasant odour which is detected by humans at a very low concentration. Both contaminants represent a potential health risk to local residents. During 1996, thiolane was observed to cause an odour nuisance both on and off-site following heavy rainfall.

Previous studies of the environmental behaviour of the compounds have generated contradictory results and the thesis addresses these inconsistencies.

The study investigates several mechanisms governing the environmental fate of sulfolane and thiolane in the sub-surface environment. In doing so, the thesis contributes to the study of environmental fate of contaminants by:
• studying the biodegradation of sulfolane under anaerobic conditions;
• establishing the adsorption behaviour of sulfolane and thiolane using batch and column sorption experiments including distinguishing adsorption and non-ideal flow behaviour in the column studies; and,
• applying a novel unsaturated adsorption technique to study the adsorption and desorption of thiolane in the vadose zone.

The principal findings of the study were:
• the development of a novel analytical technique for determining the concentration of sulfolane in aqueous solutions. The technique uses a High Performance Liquid Chromatography (HPLC) column with a Refractive Index (RI) Detector. The technique avoids the need for extraction steps prior to analysis as required by the Gas Chromatography (GC) analysis applied in some earlier studies.
• Sulfolane does not appear to biodegrade under anaerobic conditions. This result contradicts with those reported by Kim (Kim et al, 1998 and Kim, 2000) which not only reported that sulfolane degraded relatively easily but also reported thiolane generation during the experiments. The findings of this study do however agree with those of Greene et al. (1998). It is concluded that while the results of Kim appear questionable for several reasons, Greene has presented a thermodynamic argument showing that the mineralisation of sulfolane is favourable. An isotope ratioing exercise on sulfolane and thiolane extracted from groundwater samples is presented and recommended for future studies.
• Equilibrium batch adsorption experiments identified that sulfolane sorbs very slightly to Willawong site soils and that adsorption was best described using a linear sorption isotherm for the range of sulfolane grotmdwater concentrations typically observed at the site. Sorption kinetics experiments found that sorption of sulfolane occurs very rapidly. Column experiments were found to under-predict the sorption behaviour observed in batch adsorption experiments.
• Thiolane was found to sorb only moderately to Willawong site soil during equilibrium batch adsorption experiments. The batch adsorption experiments found that adsorption was best described using the non-linear Langmuir sorption isotherm although a Freundlich isotherm could also have been applied. Thiolane was found to sorb very rapidly during sorption kinetics experiments. As with the sulfolane experiments, column experiments were found to under-predict the sorption behaviour of thiolane observed in batch adsorption experiments.
• A multi-region numerical flow model was developed to investigate the inconsistencies int the degree of sorption between batch and column adsorption tests. Whilst the model was able to adequately predict the initial part of column breakthrough curves, the application of "flow interruption" methods identified that the model did not adequately reflect the flow non-idealities.
• A novel unsaturated batch adsorption technique described by Unger et al. (1996) was used rather than the more involved unsaturated column adsorption methods. Unsaturated sorption experiments identified that the sorptive capacity of soil from the Willawong Site dramatically increased with decreasing moisture contents at very low moisture contents in a manner consistent with that described in previous studies considering trichloroethylene. The results suggested that odour problems observed m the field following large rainfall event are most likely attributable to the displacement of thiolane laden air from the vadose zone rather than desorption of thiolane from extremely dry soil in the vadose zone becoming moist and thereby releasing thiolane.
Keyword Thiophenes -- Environmental aspects
Groundwater -- Pollution

Document type: Thesis
Collection: UQ Theses (RHD) - UQ staff and students only
Citation counts: Google Scholar Search Google Scholar
Created: Fri, 24 Aug 2007, 18:16:43 EST