Nicaragua is a country in which the toxic metal contamination of freshwater resources has become an increasingly important problem in certain regions posing a threat to the environment as well as to human health. Among the metals found in the waters of Nicaragua, arsenic is one of the most problematic since its long time consumption is connected to serious health problems such as cancer and neurological disorders. The arsenic contamination of water recourses in Nicaragua is mostly attributable natural factors, even though anthropogenic activities including gold mining may be a contributing factor. In this work the biopolymer Chitosan was studied as a potential adsorption material for the removal of arsenic from aqueous solutions for water treatment design purposes. The Chitosan used in this study was extracted from shrimp shells with an overall yield of 40% and a deacetylation grade of 59%. The maximum adsorption capacity was determined to 20.9 mg As/g at a controlled pH of 5.5 using the Langmuir isotherm. The adsorption was found to be strongly pH dependant with a fourfold increase in adsorption capacity when pH was well under the pKa of Chitosan. The pH dependence indicates that ionic exchange was the most important mechanism. No difference in adsorption capacity with respect to the initial pH of the solution was detected in the pH range 3-7. This was attributed to the ability of Chitosan to act as a weak base in water solutions. The arsenic was desorbed from Chitosan using NaOH, (NH4) 2SO 4 and NaCl, with a 1M NaOH solution being the most efficient displaying a concentration ratio of 1.08. The NaOH and (NH4) 2SO 4 solutions displayed a steep desorption curvature with a large fraction of the arsenic being easily desorbed. The arsenic was, however, not completely desorbed from the Chitosan implying that the adsorption capacity would decrease for the coming cycles. Being a biopolymer the Chitosan is quite easily degraded in acid and alkali solutions, which might be a limiting step for the process applicability.

Oligonucleotides (ONs) are widely used in different applications in life science, forensic, in i.e. family tree DNA test for humans and in diagnostic applications in several fields. The use of ONs in biopharmaceutical therapeutic areas also generates new challenges handling more complex molecules which results in the need of further developed analytical techniques. Anion exchange chromatography (AEX) is a common separation technique for biomolecules and is based on charge attraction between the analyte and the stationary phase. The chromatographic system is complex and often high pH and a high salt concentration is needed for the elution to occur, which in some systems can be corrosive for both the column and the instrument. The aim of this study was to evaluate new mobile phase compositions with lower salt concentrations, organic modifier, and usage of a buffer to increase the control of the pH. This was done by evaluation of three columns developed for AEX and uses different chemical and methodical modification of the mobile phase to control the retention to the stationary phase. The influence of pH, temperature, and methanol (MeOH) content in the buffer were studied by evaluation of resolution, asymmetry, and efficiency responses. Three oligonucleotides with 16, 18 and 19 T-bases in the chain were used in the study of three AIE columns. High pH, elevated temperature and the addition of an organic modifier were used for unfolding of the oligonucleotide chain and generating more efficient separations. Other parameters such as gradient slope and initial concentration of the eluting buffer were also studied, and the findings clearly show that the chromatographic conditions influence the resolution, asymmetry, and efficiency. / Oligonukleotider används i flera olika branscher som forensik och inom life sience till diagnostiska och medicinska applikationer. Eftersom applikationsområdena ökar och forskningen går framåt så blir molekylerna mer komplexa, vilket i sin tur kräver att dom analytiska teknikerna också behöver utvecklas. En vanlig separationsteknik för biomolekyler är anjonbyteskromatografi, då den bygger på laddningsattraktion mellan analyten och den stationära fasen. Oligonukleotider har en negativ nettoladdning på grund av den negativt laddade fosfatgruppen i kedjan. Genom att modifiera de kemiska egenskaperna i den mobila fasen är det därför möjligt att i viss grad kontrollera retentionen till den stationära fasen.       Då det kromatografiska systemet är komplext och det ofta behövs högt pH och/eller en hög saltkoncentration för eluering av analyten kan det i vissa system verka korrosivt för både kolonnen och instrumentet. Det initiala målet med detta arbete var att ta fram olika mobila faser med lägre saltkoncentration, organiskt lösningsmedel och användande av buffer för att kontrollera pH. Detta gjordes genom att utvärdera den kromatografiska kapaciteten hos tre olika anjonbyteskolonner samt använda olika kemiska- och metodiska modifieringar av den mobila fasen för att kontrollera analytens retention. Mer specifikt så kommer påverkan av pH, temperatur och innehåll av metanol i den mobila fasen att studeras genom att utvärdera upplösning, asymmetri och effektivitet i de erhållna kromatogrammen. Analytmixen innehåller tre olika oligonukleotider vilka består av 16, 18 eller 19 T-baser i sekvensen. Genom att höja pH, temperatur och innehåll av metanol i den mobila fasen påvisas mer effektiva separationer. Andra faktorer som gradientlutning och initialkoncentration av den eluerande fasen studeras också med goda resultat när det gäller dess påverkan på upplösning, asymmetri och effektivitet.

Ion exchange chromatography (IC) is an analytical technique used to separate charged molecules including ions, proteins, small nucleotides, and amino acids. It can function in anion or cation mode. In this dissertation, anion exchange chromatography was used, and column materials were made in our lab with resorcinarene-based compounds called cavitands. Cavitands create cavities to bind to molecules because of their three-dimensional structure. Two new gradient IC methods were established to identify and quantify perrhenate and perfluoroalkyl substances (PFAS) by customized resorcinarene-based column, zinc cyclen resoecinarene (ZCR) and arginine methyl ester (RUE) columns. The ZCR column accomplished outstanding separation of perrhenate from other anions such as chloride and sulfate by using a gradient elution of 2-60 mM NaOH. There was a logarithmic relationship between the perrhenate concentration and its retention time. In addition to separating anions, the ZCR column was able to preconcentrate perrhenate with over 90% recovery in different conditions. RUE was successfully synthesized and attached to polystyrene resin and used in IC to separate the PFAS, perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorobutanesulfonic acid (PFBS), perfluorohexanoic acid (PFHxA), perfluorohexanesulphonic acid (PFHxS), and perfluorooctanoic acid (PFOA). The sample preparation for the PFAS was simple and only needed filtration. A gradient method starting with 70 mM NaOH and going to pure water was necessary to separate the PFAS. There was no detectable PFAS in Provo tap water and Utah Lake water by our method. Although the LOD and LOQ of PFAS were not as low as the existing methods, the IC method does not require complicated sample preparation steps to separate and quantify PFAS. Binding studies of RUE and RUA were done with organic acids, including citric, malic, and succinic acid, and PFAS including PFBA, and PFHxA. The strongest binding was for L-malic acid followed by succinic acid, D-malic acid, pentanoic acid, citric acid, and dimethyl L-malate. RUE displayed some chiral recognition between L-malic acid and D-malic acid. Unfortunately, it did not show significant differences in binding between the different PFAS even though RUE had been able to separate them by IC.

No description available.

I Sverige har ungefär 1,2 miljoner människor enskild dricksvattenförsörjning och en stor andel av dessa har problem med vattenkvalitet. En utvärdering av reningstekniker har inletts av företaget Ecoloop och Utvecklingscentrum för vatten och detta examensarbete fördjupar och följer upp de inledande resultaten från det projektet. Med hjälp av en litteraturstudie, modellering i Visual MINTEQ och fem fallstudier utvärderades reningsteknikerna jonbytarfilter och nanofilter avsett för enskild dricksvattenförsörjning med avseende på reduktion av föroreningarna bly och uran. Fallstudierna visar att jonbytarfilter kan fungera väl för att reducera uranhalter men en viss inkörningsperiod förekommer där bieffekter, exempelvis kemisk smak, kan förekomma samt att underhåll är viktigt för att fortsätta ha en hög reduktionsgrad. Fallstudierna kunde ej besvara ifall nanofilter är en lämplig reningsteknik för ändamålet att reducera halter av bly och uran under de gränsvärden som finns, eftersom de membranfilter som använts i fallstudierna visade sig ha för stor porstorlek för att kallas nanofilter. En slutsats är att det är viktigt att fortsätta med provtagning av vattnet även efter att ett filter installerats. Utöver det genomfördes intervjuer och en enkätundersökning som undersökte hur kommuner i Sverige arbetar för att möta enskilda brunnsägare i deras utmaningar med vattenkvalitet. Intervjuerna och enkätsvaren visar på en variation där några kommuner jobbar aktivt för att stötta de enskilda brunnsägarna med rådgivning, bidrag och förebyggande åtgärder medan andra kommuner är mer passiva och låter de enskilda ta eget ansvar för sitt vatten. / About 1.2 million people in Sweden rely on their own private drinking water supply for their daily needs and a large portion of those have problems with water quality. An evaluation of water treatment technology intended for private wells has been initiated by the companies Ecoloop and Utvecklingscentrum för vatten and this master’s thesis further develops and follows up the initial results. By conducting a literature review, doing modelling in Visual MINTEQ and carrying out five case studies the two water treatment techniques nanofilter and ion exchange are evaluated in the context of domestic water supplies with water quality problems caused by either lead or uranium. The case studies shows that ion exchange filters can reduce uranium in drinking water below the threshold value but with some initial side effects (i.e., chemical taste of the water). The case studies could not show if nanofilters are suitable to reduce lead or uranium from domestic water supplies, since the pore size was found to be too big for the membrane filters used in the case studies to be called nanofilters. This concludes that it is important to proceed with sampling of the water even after installing a filter for water treatment. Additionally, interviews and a survey were conducted which investigated how municipalities in Sweden are working to meet private well owners in their challenges with water quality. The answers from the interviews and the survey displays a variation where some municipalities are actively supporting the private well owners through counselling, grants, and preventive measures while other municipalities are more passive and leaves the individual well owners responsible to look after their water quality by themselves.

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No description available.

Doctor of Philosophy / Rare earth elements (REEs) play a significant role in industrial production. Currently, much effort has been made to recover REEs from clays isolated from mining wastes such as coal byproducts. However, the concentrations of REEs in those clayey waste materials are too low, and they are not amenable to leaching even using strong acids. The developed extraction techniques usually need to be carried out at elevated temperatures (e.g., >100 oC) and consume substantial amounts of chemicals, which are not cost-effective and environmentally friendly. Given the issues, this study proposed a novel leaching technology that can recover REEs from clayey waste materials under mild conditions (<100 oC). Firstly, to simulate the recovery of REEs from coal-based clay materials, a monazite sample was pretreated with caustic soda (i.e., NaOH) at 80 oC for 24 h to convert the difficult-to-dissolve REEs (i.e., rare earth phosphate) into readily soluble forms (rare earth hydroxide), after which they were dissolved in 0.5 M ammonium sulfate solution at pH 4 and room temperature. A conceptual model was developed to explain the leaching mechanism of ammonium sulfate, which was found to be an ion exchange process. The proposed leaching process was also used to extract REEs from clay materials isolated from coal-based clay samples. A chelating ligand named ethylenediaminetetraacetic acid (i.e., EDTA) was added to the dilute NaOH solutions to reduce the alkali consumption during NaOH pretreatment. It was found that the presence of EDTA can improve the performance of NaOH pretreatment. Additionally, the content of REEs in a kaolinite waste material was physically upgraded to 10,765 ppm with ~72% recovery using a novel separation technique called hydrophobic-hydrophilic separation (HHS). The NaOH pretreatment and ammonium sulfate leaching process can also effectively recover REEs from the concentrate. The proposed leaching technology in this study can extract REEs from other low-grade clayey waste materials under mild conditions, which helps reduce wastewater generation and energy consumption. Furthermore, it will relieve the supply risk of REEs in the future.

Shale oil is an attractive, alternative fuel source for a world in which there is an increasing demand for energy. However, it is necessary to assess the environmental impacts of the shale oil industry before widescale production is begun. Diversity of retorting processes, the subsequent variability in waste products and the possible waste management schemes makes assessment of these impacts complicated. Waste treatment and disposal are areas which must be researched thoroughly. To properly evaluate the environmental risks associated with the disposal of processed shales and process wastewaters, an appreciation for the sorption/desorption (S/D) characteristics of oil shales is required. The overall objective of this research was to evaluate the S/D capacity of four types of shale: Antrim (spent, eastern shale), Anvil (raw, western shale), Oxy 6 and Run 16 (spent, western shales). Batch and continuous-flow, column experiments were performed in which the S/D behavior of five cations (As, Ca, Cd, Fe, and K) and three anions (F, SO₄, and HCO₃/CO₃) was monitored. The conductivity, redox potential, and pH of the eluent fluids were also determined. This study showed that retort temperature and porosity of the various shales had a significant effect an their S/D characteristics. Batch elution trials with spent shales produced eluents having a characteristic pH in the range 8.5 to 11.5. In these experiments, the shales retorted at lower temperatures (660°C and 793°C) released higher levels of Ca, K, and SO₄ than did a higher temperature, retorted shale (800 to 1000°C) and raw shale. The shales retorted at lower temperatures also had the highest porosities of the four shales and exhibited a greater capacity for sorption of As and F than did the other shales. Continuous-flow, elution trials showed that most inorganics monitored were flushed from the columns of shale in the first 5 to 8 pore volumes of effluent. / Master of Science

Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Recently concern has been raised regarding effluent from wine cellars, as it often does not comply with environmental legislation. It was with this in mind that the effluent problem at Ashton Cellars was addressed. After carrying out a water audit of the plant, described in Chapter 3, it was concluded that the ion exchange plant is a significant contributor to the low pH and high conductivity of the effluent dam. Decreasing the effluent from the ion exchange plant should therefore help in improving the total effluent quality. During the water audit opportunities to improve the effluent by making small process changes in the cellar were identified. The primary objective of this study was to provide guidelines to improve the quality and decrease the volume of the effluent from the ion-exchange plant to more environmentally acceptable levels, whilst maintaining product specifications and production rates. This was achieved by studying the operation of the plant (Chapter 4) and testing the characteristics of the current and alternative resins (Chapter 5). Auditing of the ion exchanges plant included a detailed analysis of the regeneration and loading of the ion exchange columns. It was concluded that the operation of the plant can only be optimised once pH and/or conductivity meters, and preferably an automated control system, are installed on the plant. The results given in this thesis can be used as a guide when setting up such a control system. Laboratory testing of the resins revealed that the cation resin currently being used on the plant has been fouled and loads at a slow rate. When the resins are replaced, the use of Purolite CISO and Purolite A103S should be considered as these resins gave the most favourable results. Some alternative treatment methods for the processing of grape must, have been mentioned in Chapter 6. / AFRIKAANSE OPSOMMING: Al meer kornrner word deesdae uitgespreek oor wynkelders se afvalwater, omdat dit meerendeels nie aan die vereistes van omgewingswetgewing voldoen nie. Dit was met hierdie probleem in die oog dat die afvalwater probleem by Ashton Kelders ondersoek IS. Nadat 'n wateroudit van die fabriek, soos beskryf in Hoofstuk 3, uitgevoer is, is daar tot die slotsom gekom dat die ioonuitruilsisteem 'n groot bydra tot die lae pH en hoe konduktiwiteit van die afvaldam lewer. Indien die ioonuitruilsisteem se uitvloeisel verminder kon word, sou dit tot 'n groot mate bydrae tot 'n verbetering van die totale uitvloei kwaliteit. Gedurende die wateroudit is verskeie moontlikhede vir die verbetering van die uitvloei deur klein prosesveranderinge aan te bring, geidentifiseer. Hierdie studie het as hoof oogmerk die daarstelling van riglyne vir die verbetering van die kwaliteit en grote van die afvalstrome van die ioonuitruilsisteem om sodeende aan omgewingswetgewing te voldoen, maar ter selfder tyd die produk spesifikasies en tempos te handhaaf. Dit is gedoen deur die huidige bedryf van die fabriek te bestudeer (Hoofstuk 4) en die eienskappe van die huidige en altematiewe ioonuitruilharse te toets (Hoofstuk 5). Die oudit van die ioonuitruilsisteem het 'n gedetaileerde anaIiese van die hergenerasie en lading van die ioonuitruilkolornrne ingesluit. Daar is tot die slotsom gekom dat die bedryf van die sisteem alleenlik geoptirniseer kon word indien pH en/of konduktiwiteitsmeters, en verkieslik 'n automatiese kontrolesisteem geinstalleer word. Die resultate van hierdie tesis kan as basis vir so 'n kontrole sisteem gebruik word. Die laboratoriumtoetse op die harse het aan die lig gebring dat die katioonhars wat tans in gebruik is, baie vervuil is en net teen 'n lae tempo belaai kan word. Wanneer die harse vervang word, word die gebruik van Purolite el50 en Purolite A103S aangeraai, aangesien hierdie harse die beste resultate gelewer het. Altematiewe behandelingsmetodes van druifmos is in Hoofstuk 6 genoem.