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Protein-induced wine haze is a major concern to the wine industry worldwide. While the presence of protein haze is unlikely to affect the sensory profile, consumers will generally reject wines containing hazes as they appear microbially spoiled. Consequently, an important step during commercial winemaking is to treat wines with bentonite, which removes heat unstable proteins by adsorption, and prevents haze formation. Whilst this process is effective, it is claimed to adversely affect the quality of the treated wine under certain conditions. Furthermore, 5-10% of the wine volume is typically occluded in bentonite lees. This wine is either lost or substantially diminished in quality and value during recovery. Therefore the development of alternative and economically viable process technologies that maintain wine quality and reduce costs would be highly desirable. This thesis is concerned with the development of alternative and innovative approaches to bentonite treatment of wine. Particular emphasis was placed on developing practical research outcomes that could be readily commercially adopted. Pursuant to this, fundamental research regarding the mechanics of protein adsorption onto bentonite was undertaken to gain an understanding of how bentonite properties relate to adsorption and settling behaviour in wine. The effect of bentonite heat treatment on protein adsorption performance and settling behaviour in a model wine was also investigated. In general, heating was found to increase the initial hindered settling velocity and reduce both protein adsorption capacity and the final volume of lees. Particle size, pH and cation exchangeability of bentonites and the changes that occur to these properties on heating are related to the nature of bonding between cations and the clay surface, as are protein adsorption performance and settling behaviour. Partial Least Squares (PLS) Analysis showed that the variance in individual cation exchangeability and the total cation exchange capacity was primarily responsible for the observed variance in protein adsorption performance and settling behaviour. PLS analysis was also used to develop correlations for the prediction of adsorption and settling behaviour, based on the physical and chemical properties of the bentonites tested. Qualitative comparison of the volume fraction of model wine occluded by each of the bentonites indicated that certain heat treatments may result in a combination of protein adsorption performance and settling behaviour which would produce a significant reduction in wine loss. The effect of different factors on adsorption of a purified grape protein (VVTL1) in a model wine was investigated using a factorial design approach with surface response analysis. Adsorption of VVTL1 by sodium bentonite was well characterised by the Langmuir adsorption isotherm. pH, temperature, potassium concentration ([K]), and the pH*[K]interaction were all found to have a significant effect (p < 0.05) on the adsorption capacity. Block effects appeared to correctly correlate with bentonite slurry age, suggesting that increasing slurry age may have a positive effect on adsorption capacity. Ethanol concentration, phenolic (caffeic acid and catechin) oncentration, sugar (glucose and fructose) concentration, as well as the pH*temperature and temperature*[K] interactions did not have a significant effect. The equilibrium constant was found to be independent of the factors studied. This may be explained by changes in protein structure and charge with pH, which affect electrostatic interaction with the bentonite surface. Variation in potassium concentration can cause similar effects and may also influence adsorption capacity by affecting bentonite swelling and zeta potential. This knowledge was applied to the development of in-line dosing of bentonite as an alternative process strategy for commercial use. Field tests of in-line dosing at a commercial winery were conducted on a Sultana wine and Gordo (Muscat of Alexandria) juice with Vitiben and SIHA-Aktiv-Bentonit G bentonites. Fining performance was monitored by heat testing and quantification of heat unstable protein by HPLC. Heat test turbidity and heat unstable protein concentration were reduced in a similar manner upon fining. These reductions were achieved with a contact time of less than two minutes. Sensory evaluation of Sultana wine fined with Vitiben by balanced reference duo-trio difference tests did not detect any difference between untreated, in-line dosed and batch fined wine. A dynamic simulation model of in-line dosing was developed and compared with field trial results, marking the first quantitative study of the dynamic adsorption kinetics of wine protein adsorption onto bentonite. The simulation results confirmed the rapid adsorption behaviour observed during field testing, and provided strong evidence that protein adsorption occurs predominantly on the external particle surface only, with adsorption kinetics being limited by external-film mass transfer. Incomplete separation of bentonite from wine/juice during centrifugation produced a carryover of up to 30% of the added bentonite into the clarified wine. If this problem can be overcome, use of in-line dosing instead of batch fining could eliminate significant value losses presently arising from quality downgrades of wine recovered from bentonite lees by rotary drum vacuum filtration. Moreover, in-line dosing of selected heattreated bentonites under optimal wine or juice conditions may provide even further costs savings whilst maintaining wine quality. / Thesis (Ph.D.)-- University of Adelaide, School of Chemical Engineering, 2006.

Protein-induced wine haze is a major concern to the wine industry worldwide. While the presence of protein haze is unlikely to affect the sensory profile, consumers will generally reject wines containing hazes as they appear microbially spoiled. Consequently, an important step during commercial winemaking is to treat wines with bentonite, which removes heat unstable proteins by adsorption, and prevents haze formation. Whilst this process is effective, it is claimed to adversely affect the quality of the treated wine under certain conditions. Furthermore, 5-10% of the wine volume is typically occluded in bentonite lees. This wine is either lost or substantially diminished in quality and value during recovery. Therefore the development of alternative and economically viable process technologies that maintain wine quality and reduce costs would be highly desirable. This thesis is concerned with the development of alternative and innovative approaches to bentonite treatment of wine. Particular emphasis was placed on developing practical research outcomes that could be readily commercially adopted. Pursuant to this, fundamental research regarding the mechanics of protein adsorption onto bentonite was undertaken to gain an understanding of how bentonite properties relate to adsorption and settling behaviour in wine. The effect of bentonite heat treatment on protein adsorption performance and settling behaviour in a model wine was also investigated. In general, heating was found to increase the initial hindered settling velocity and reduce both protein adsorption capacity and the final volume of lees. Particle size, pH and cation exchangeability of bentonites and the changes that occur to these properties on heating are related to the nature of bonding between cations and the clay surface, as are protein adsorption performance and settling behaviour. Partial Least Squares (PLS) Analysis showed that the variance in individual cation exchangeability and the total cation exchange capacity was primarily responsible for the observed variance in protein adsorption performance and settling behaviour. PLS analysis was also used to develop correlations for the prediction of adsorption and settling behaviour, based on the physical and chemical properties of the bentonites tested. Qualitative comparison of the volume fraction of model wine occluded by each of the bentonites indicated that certain heat treatments may result in a combination of protein adsorption performance and settling behaviour which would produce a significant reduction in wine loss. The effect of different factors on adsorption of a purified grape protein (VVTL1) in a model wine was investigated using a factorial design approach with surface response analysis. Adsorption of VVTL1 by sodium bentonite was well characterised by the Langmuir adsorption isotherm. pH, temperature, potassium concentration ([K]), and the pH*[K]interaction were all found to have a significant effect (p < 0.05) on the adsorption capacity. Block effects appeared to correctly correlate with bentonite slurry age, suggesting that increasing slurry age may have a positive effect on adsorption capacity. Ethanol concentration, phenolic (caffeic acid and catechin) oncentration, sugar (glucose and fructose) concentration, as well as the pH*temperature and temperature*[K] interactions did not have a significant effect. The equilibrium constant was found to be independent of the factors studied. This may be explained by changes in protein structure and charge with pH, which affect electrostatic interaction with the bentonite surface. Variation in potassium concentration can cause similar effects and may also influence adsorption capacity by affecting bentonite swelling and zeta potential. This knowledge was applied to the development of in-line dosing of bentonite as an alternative process strategy for commercial use. Field tests of in-line dosing at a commercial winery were conducted on a Sultana wine and Gordo (Muscat of Alexandria) juice with Vitiben and SIHA-Aktiv-Bentonit G bentonites. Fining performance was monitored by heat testing and quantification of heat unstable protein by HPLC. Heat test turbidity and heat unstable protein concentration were reduced in a similar manner upon fining. These reductions were achieved with a contact time of less than two minutes. Sensory evaluation of Sultana wine fined with Vitiben by balanced reference duo-trio difference tests did not detect any difference between untreated, in-line dosed and batch fined wine. A dynamic simulation model of in-line dosing was developed and compared with field trial results, marking the first quantitative study of the dynamic adsorption kinetics of wine protein adsorption onto bentonite. The simulation results confirmed the rapid adsorption behaviour observed during field testing, and provided strong evidence that protein adsorption occurs predominantly on the external particle surface only, with adsorption kinetics being limited by external-film mass transfer. Incomplete separation of bentonite from wine/juice during centrifugation produced a carryover of up to 30% of the added bentonite into the clarified wine. If this problem can be overcome, use of in-line dosing instead of batch fining could eliminate significant value losses presently arising from quality downgrades of wine recovered from bentonite lees by rotary drum vacuum filtration. Moreover, in-line dosing of selected heattreated bentonites under optimal wine or juice conditions may provide even further costs savings whilst maintaining wine quality. / Thesis (Ph.D.)-- University of Adelaide, School of Chemical Engineering, 2006.

The hydraulic conductivity of sand-bentonite mixtures (SBMs) was measured to investigate the effects of mixing method, uniformity, and hydration of the mixtures. Triaxial tests were completed to determine the hydraulic conductivity of each specimen. Specimens using Ottawa sand and Wyoming bentonite, prepared with dry and suspension mixing conditions that altered the degree of hydration and swelling of bentonite, had varying bentonite content by percentage dry weight of sand. The conclusions of this experiment can be applied to the construction of cut off walls used in levees to mitigate groundwater seepage through underlying pervious layers. Eleven sand-bentonite specimens were tested in this study: nine were prepared using dry mixing and two were prepared using suspension mixing. The results do not show strong correlations between hydraulic conductivity and bentonite content, mixing method, clay void ratio, or time. Therefore, further investigation of the results was necessary. The bentonite void ratio (clay void ratio) assumes that bentonite is fully swelled for both blocked and partially blocked flow. Blocked flow occurs when the swelled bentonite blocks all the sand voids, forcing the water to flow within the bentonite voids. However, the results in this study shows that the concept of clay void ratio doesn’t capture the performance of SBMs when the bentonite is partially swelled; therefore, a new concept of effective clay void ratio was introduced to account for bentonite partial swelling. The effective clay void ratio determines the volume of swelled clay as a function of the volume of fully swelled bentonite. This is useful when comparing results with literature or predicting hydraulic conductivity in cases where only partial swelling of bentonite is expected. / text

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The UK Committee on Radioactive Waste Management (CoRWM) recommended, in 2006, that geological disposal coupled with safe and secure interim storage should have been the way forward for the long-term management of the UK’s higher activity wastes. The design of the underground repository contemplates the presence of bentonite plugs to seal access galleries and deposition boreholes and hence the interaction between the clay-based backfill material and the underground water. Remote monitoring of the fluid saturation of the barrier, the waste canisters and of the surrounding subsurface Geological Disposal Facility environment assumes a relevant importance to guarantee the safety of the repository and to increase the confidence and the reliance of the communities living in areas potentially affected by the repository over time. This remote monitoring of the Engineered Barrier System represents a technical challenge due to the unsuitability of some of the traditional geotechnical techniques or to the intrinsic unreliability of many geophysical prospecting techniques in providing information about the evolution of the Thermo-Hydro-Mechanical-Chemical coupling of the system over long timescales up to and including post-closure evolution. In this project, I offer an initial approach to an innovative way of using mineral magnetism, and, in particular, I analyse the possible exploitation of corrosion-induced variations of the magnetic properties of several magnetic materials to monitor water saturation in the Engineered Barrier System and its evolution through time. Initially the reactivity of several natural and synthetic materials is tested under different “extreme” conditions to analyse the feasibility of the research concept and identify the materials more adapt to carry out the job. The effects that the corrosion of the magnetic materials has on the clay matrix is also analysed in detail throughout all the thesis work. The initial tests lead to the identification of specific transitions in the hysteretic behaviour of three of the initial candidates (Nd-Fe-B, AlNiCo and SmCo alloys). These three materials are subsequently tested under conditions closer to a real “evolved” Barrier System, where the groundwater interacts, with cementiferous grout producing hyperalkaline leachates. The final tests consider the temporal evolution (after 4, 8 and 12 months) of the magnetic properties of these materials in a dysoxic environment under imposed fluid-flow. The results show a clear change in the hysteretic properties of the three materials analysed and the feasibility of the monitoring of the Barrier fluid saturation in the short-term. Furthermore, the corrosion of the magnets, under the conditions applied, did not cause formation of non-swelling clays.

The major drawback of crossflow membrane filtration is that permeate flux declines with time as a result of the increase in total membrane resistance. Pulsatile flow is well known to reduce the resistance and enhance permeate flux. This study applied pulsatile flow induced by the oscillation of a collapsible tube to microfiltration and ultrafiltration, to improve filtration performance expressed as permeate flux enhancement and backflushable resistance reduction. Three membranes (ceramic tubular microfiltration, PVDF spiral-wound microfiltration and PS hollow-fibre ultrafiltration) and two media (bentonite suspension and whey solution) were used. In bentonite pulsatile microfiltration with the tubular membrane, up to 300% of permeate flux enhancement and 90% of backflushable resistance reduction were achieved. In bentonite and whey pulsatile microfiltration with the spiral-wound membrane, moderate improvements were gained: for bentonite, the highest increase in permeate flux was 51% and decrease in backflushable resistance was 45%; for whey, the highest permeate flux enhancement and backflushable resistance reduction were 36% and 38% respectively. In ultrafiltration of both media, no significant performance improvement was found. This is thought due in the one case to the relatively minute membrane pore size, and in the other to the large irreversible resistance created by whey solution. Transmural pressure at the collapsible tube downstream end indicates the tube compression and influences the pulsation vigour. Increasing the transmural pressure was an effective way to improve filtration performance. In bentonite microfiltration with the tubular membrane, increasing crossflow velocity was also effective, but increasing transmembrane pressure was not. Analysis of pulsatility parameters showed that the pulsatile flow always resulted in enhanced wall shear, and induced pore backflush always in the tubular membrane and sometimes in the HF membrane. These mechanistic findings helped to understand the filtration performance improvements. The analysis of energy consumption in bentonite microfiltration with the tubular membrane clearly demonstrated the benefit of applying the collapsible-tube-induced pulsatile flow in energy utilisation. The system specific energy could be reduced more than 70 % relative to the equivalent steady microfiltration permeate flux. For a given specific energy, the permeate flux could be increased by a factor of nearly four.

The main issue of this thesis was to obtain information ondiffusion and sorption behaviour on organic colloids incompacted bentonite through experimental studies. It was tostudy if bentonite is an efficient barrier for organic colloidsor not. If colloids diffuse into bentonite in sufficientconcentrations, the speciation and sorption characteristics ofdiffusing radionuclides will change. Colloids might facilitatetransport, especially of radionuclides immobilised by strongsorption on bentonite. Laboratory experiments were performed to determine thestability of humic substances (HS) and bentonite colloids insolutions of ionic strengths representative for deep graniticgroundwaters. The HS but not the bentonite colloids were foundto be stable in these conditions. The competition between complexation with HS and sorption onbentonite of the cations Sr(II) and Eu(III) were studied inbatch experiments. Eu(III) was foundto complex with HS to bigextent. If HS is present in sufficient concentrations andstable in compacted bentonite, the Eu(III)-HS will be a speciesthat has to be accounted for. Sr(II) sorption decreases in thepresence of HS at ionic strength 0.01 M, but not at 0.1 M.Sr(II) sorbs weakly on bentonite and forms weak complexes withHS. The diffusion of Sr(II) in bentonite compacted to 1.8 g/cm3dry density and equilibrated with 0.1 M NaClO4 solutions wasstudied with and without HS in the system. The HS concentrationwas varied between 0.1 and 0.2 g/l. The Sr(II) diffusion wasnot affected by the presence of HS, which is in agreement withthe competition data of complexation to HS and sorption onbentonite. Diffusion of Co(II) and Eu(III) was studied in bentonite ofcompaction 0.6-1.8 g/cm3in the presence of HS. Eu(III)diffusion without HS in the system was studied as well. Co(II)diffusivity was found to increase significantly in the presenceof HS and the Kd-values decreased drastically. The decrease inthe Kd-values was found to be ionic strength dependent. This isexplained by HS complexation capacity decreases with increasingionic strength. The results indicate that the strongly surfacecomplexed Co(II) is mobilised by HS, but the Co-HS is not theonly diffusing Co(II) species in the experimental conditions ofthis study. Considering that Eu(III) sorbs strongly on bentonite, thediffusivity of Eu(III) was found to be rather high at ionicstrength 0.01 M. The high diffusivity rates are explained bythat the cation-exchanged Eu(III) around 1 % of the totalsorption is in practise mobile. In the presence of HS, Eu(III)diffusivity increases and the sorption decrease drastically.The Eu(III)-HS seems to be the dominating Eu(III) species whenthe HS concentrations are sufficiently high, and the HSsorption and diffusivity govern the system. <b>Keywords:</b>Diffusion, sorption, complexation, stability,bentonite, humic substances, Sr(II), Co(II) and Eu(III).