<p>This study evaluated SO4 2- removal from circumneutral mine water (CMW) collected from Middleburg coal mine using coal FA collected from Hendrina power station. The following parameters were investigated: the effect of the amount of FA, the effect of the final pH achieved during treatment, the effect of the initial pH of the mine water and the effect of Fe and Al on SO4 2- removal from mine water. The precipitation of ettringite at alkaline pH was evaluated to further reduce the SO4 2- concentration to below the DWAF limit for potable water. Removal of SO4 2- from mine water was found to be dependent on: the final pH achieved during treatment, the amount of FA used to treat the mine water and the presence of Fe and Al in the mine water. Treatment of CMW using different CMW:FA ratios / 5:1, 4:1, 3:1, and 2:1 resulted in 55, 60, 70 and 71 % SO4 2- removal respectively. Treatment of CMW to pH 8.98, 9.88, 10.21, 10.96, 11.77 and 12.35 resulted in 6, 19, 37, 45, 63 and 71 % SO4 2- removal respectively. When the CMW was modified by adding Fe and Al by mixing with Navigation coal mine AMD and treated to pH 10, 93 % SO4 2- removal was observed. Further studies were done to evaluate the effects of Fe and Al separately. Treatment of simulated Fe containing AMD (Fe-AMD) to pH 9.54, 10.2, 11.8, and 12.1 resulted in 47, 52, 65, and 68 % SO4 2- removal respectively. When Al containing AMD was treated to pH 9.46, 10.3, 11.5 and 12 percentage SO4 2- removal of 39, 51, 55 and 67 % was observed respectively.</p>

<p>This study evaluated SO4 2- removal from circumneutral mine water (CMW) collected from Middleburg coal mine using coal FA collected from Hendrina power station. The following parameters were investigated: the effect of the amount of FA, the effect of the final pH achieved during treatment, the effect of the initial pH of the mine water and the effect of Fe and Al on SO4 2- removal from mine water. The precipitation of ettringite at alkaline pH was evaluated to further reduce the SO4 2- concentration to below the DWAF limit for potable water. Removal of SO4 2- from mine water was found to be dependent on: the final pH achieved during treatment, the amount of FA used to treat the mine water and the presence of Fe and Al in the mine water. Treatment of CMW using different CMW:FA ratios / 5:1, 4:1, 3:1, and 2:1 resulted in 55, 60, 70 and 71 % SO4 2- removal respectively. Treatment of CMW to pH 8.98, 9.88, 10.21, 10.96, 11.77 and 12.35 resulted in 6, 19, 37, 45, 63 and 71 % SO4 2- removal respectively. When the CMW was modified by adding Fe and Al by mixing with Navigation coal mine AMD and treated to pH 10, 93 % SO4 2- removal was observed. Further studies were done to evaluate the effects of Fe and Al separately. Treatment of simulated Fe containing AMD (Fe-AMD) to pH 9.54, 10.2, 11.8, and 12.1 resulted in 47, 52, 65, and 68 % SO4 2- removal respectively. When Al containing AMD was treated to pH 9.46, 10.3, 11.5 and 12 percentage SO4 2- removal of 39, 51, 55 and 67 % was observed respectively.</p>

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-03-15T16:57:36Z No. of bitstreams: 1 KAMILA FREITAS PORTO - DISSERTAÇÃO PPGEQ 2017..pdf: 2416618 bytes, checksum: 9e62c85bd253dcc11c3e6cb2c6a8e8ac (MD5) / Made available in DSpace on 2018-03-15T16:57:36Z (GMT). No. of bitstreams: 1 KAMILA FREITAS PORTO - DISSERTAÇÃO PPGEQ 2017..pdf: 2416618 bytes, checksum: 9e62c85bd253dcc11c3e6cb2c6a8e8ac (MD5) Previous issue date: 2017-03-30 / Visando a problemática da disponibilidade e da qualidade hídrica, a dessalinização de águas através de processos com membranas é uma das alternativas para amenizar o problema da baixa qualidade e da escassez, produzindo água de boa qualidade. Porém, neste método ainda existem alguns obstáculos a serem vencidos, um deles é a incrustação nas membranas. Para resolver este problema em sistemas de osmose inversa, geralmente utilizam-se antiincrustantes comerciais, os quais são específicos para determinados sais. Dentre os íons comumente presentes em águas estão o bicarbonato (HCO3-) e o carbonato (CO32-), este último facilmente encontrado na forma de carbonato de cálcio (CaCO3), que em determinadas condições precipita, baixando a eficiência da membrana e, consequentemente, a quantidade de água produzida. Através do Índice de Saturação de Langelier (ISL) é possível detectar o risco de formação de precipitados deste sal nas águas salobras. Esse trabalho descreve os resultados da pesquisa realizada no estudo do pré-tratamento de águas para a diminuição do ISL, comparando o desempenho do ácido clorídrico versus antiincrustante comercial, Flocon 260. Para este fim, neste estudo inicialmente utilizou de águas sintéticas e posteriormente águas de poços, realizando testes em pequena e grande escalas. O HCl se mostrou um bom antiincrustante, uma vez que foi possível obter valores do ISL abaixo de zero para os dois tipos de experimentos, em escala de bancada e de piloto. Para os dois tipos de água foi possível se observar bons resultados e, quando comparado com o antiincrustante comercial observou-se uma melhor relação custo-benefício / Aiming at the issue of availability and water quality, the desalination of water through membrane processes is one of the alternatives to alleviate the problem of low quality and scarcity, producing good quality water. However, in this method there are still some obstacles to be overcome, one of them is the incrustation in the membranes. To solve this problem in reverse osmosis systems, commercial antifoulants are generally used, which are specific for particular salts. Among the ions commonly present in water are bicarbonate (HCO3-) and carbonate (CO32-), the latter easily found in the form of calcium carbonate (CaCO3), which under certain conditions precipitates, lowering the efficiency of the membrane and, consequently , The amount of water produced. Through the Langelier Saturation Index (ISL) it is possible to detect the risk of precipitation of this salt in brackish waters. This work describes the results of the research carried out in the study of water pretreatment for the reduction of ISL, comparing the performance of hydrochloric acid versus commercial antifoulant, Flocon 260. For this purpose, in this study initially used synthetic waters and later waters of Wells, performing tests on small and large scales. HCl proved to be a good antifouling since it was possible to obtain ISL values below zero for the two types of experiments, bench scale and pilot scale. For both types of water it was possible to observe good results and, when compared with the commercial antifoulant, a better cost-benefit ratio was observed.

Magister Scientiae - MSc / This study evaluated SO4 2- removal from circumneutral mine water (CMW) collected from Middleburg coal mine using coal FA collected from Hendrina power station. The following parameters were investigated: the effect of the amount of FA, the effect of the final pH achieved during treatment, the effect of the initial pH of the mine water and the effect of Fe and Al on SO4 2- removal from mine water. The precipitation of ettringite at alkaline pH was evaluated to further reduce the SO4 2- concentration to below the DWAF limit for potable water. Removal of SO4 2- from mine water was found to be dependent on: the final pH achieved during treatment, the amount of FA used to treat the mine water and the presence of Fe and Al in the mine water. Treatment of CMW using different CMW:FA ratios; 5:1, 4:1, 3:1, and 2:1 resulted in 55, 60, 70 and 71 % SO4 2- removal respectively. Treatment of CMW to pH 8.98, 9.88, 10.21, 10.96, 11.77 and 12.35 resulted in 6, 19, 37, 45, 63 and 71 % SO4 2- removal respectively. When the CMW was modified by adding Fe and Al by mixing with Navigation coal mine AMD and treated to pH 10, 93 % SO4 2- removal was observed. Further studies were done to evaluate the effects of Fe and Al separately. Treatment of simulated Fe containing AMD (Fe-AMD) to pH 9.54, 10.2, 11.8, and 12.1 resulted in 47, 52, 65, and 68 % SO4 2- removal respectively. When Al containing AMD was treated to pH 9.46, 10.3, 11.5 and 12 percentage SO4 2- removal of 39, 51, 55 and 67 % was observed respectively. / South Africa

>Magister Scientiae - MSc / South African power stations generate large amounts of highly alkaline fly ash (FA). This waste product has a serious impact on the environment. Acid mine drainage (AMD) is another environmental problem associated with mining. AMD has high heavy metal content in addition to high SO/- concentrations. Several studies have shown that 80-90 % of SO/- can be removed when FA is codisposed with AMD rich in Fe and AI. In South Africa, many sources of contaminated mine waters have circumneutral pH and much lower concentrations of Fe and Al (unlike AMD), but are rich in Ca, Mg and SO2-4. This study evaluated sol removal from circumneutral mme water (CMW) collected from Middleburg coal mine using coal FA collected from Hendrina power station. The following parameters were investigated: the effect of the amount of FA, the effect of the final pH achieved during treatment, the effect of the initial pH of the mine water and the effect of Fe and Al on SO/- removal from mine water. The precipitation of ettringite at alkaline pH was evaluated to further reduce the SO/- concentration to below the DWAF limit for potable water. Removal of sol from mine water was found to be dependent on: the final pH achieved during treatment, the amount of FA used to treat the mine water and the presence of Fe and Al in the mine water. Treatment of CMW using different CMW:FA ratios; 5:1, 4:1, 3:1, and 2:1 resulted in 55, 60, 70 and 71 % SO/- removal respectively. Treatment of CMW to pH 8.98, 9.88, 10.21, 10.96, 11.77 and 12.35 resulted in 6, 19, 37, 45, 63 and 71 % SO/- removal respectively. When the CMW was modified by adding Fe and Al by mixing with Navigation coal mine AMD and treated to pH 10, 93 % SO/- removal was observed. Further studies were done to evaluate the effects of Fe and Al separately. Treatment of simulated Fe containing AMD (Fe-AMD) to pH 9.54, 10.2, 11.8, and 12.1 resulted in 47, 52,65, and 68 % SO/- removal respectively. When Al containing AMD was treated to pH 9.46, 10.3, 11.5 and 12 percentage SO/- removal of 39, 51,55 and 67 % was observed respectively. Ion chromatography (IC), inductively coupled plasma-mass spectrometry (ICPMS) and inductively coupled plasma-atomic emission (ICP-AES) analysis of the product water, x-ray diffraction (XRD) and x-ray fluorescence (XRF) spectrometry analysis of FA and solid residues collected after treatment of mine water complemented with PHREEQC thermodynamic modelling have shown that the mechanism of S042 - removal from mine water depends on the composition of the mine water. The sol- removal mechanism from CMW was observed to depend on gypsum precipitation. On the other hand sol- removal from mine water containing Fe and Al was dependent on the precipitation of gypsum and Fe and Al oxyhydroxysulphates. The oxyhydroxysulphates predicted by PHREEQC as likely to precipitate were alunite, basaluminite, ettringite, jarosites and jurbanite. Treatment of CMW with FA to pH 12.35 removed sol- from 4655 ppm to approximately 1500 ppm. Addition of amorphous AI(OH)3 to CMW that was treated to pH greater than 12 with FA was found to further reduce the sol concentration to 500 ppm which was slightly above the threshold for potable water of 400 ppm. The further decrease of sol concentration from 1500 to 500 ppm was due to ettringite precipitation. Mine water treatment using FA was found to successfully remove all the major elements such as Fe, AI, Mn and Mg to below the DWAF limit for drinking water. The removal of the major elements was found to be pH dependent. Fe and Al were removed at pH 4-7, while Mn and Mg were removed at pH 9 and 11 respectively. The process water from FA treatment followed by gypsum seeding and addition of AI(OH)3 had high concentration of Ca, Cr, Mo and B and a pH of greater than 12. The pH of the process water from FA treatment followed by gypsum seeding and addition of AI(OH)3 was reduced by reacting the process water with CO2 to 7.06. The process water from the carbonation process contained trace elements such as Cr, Mo and B above the DWAF effluent limit for domestic use. Carbonation of the process water reduced the water hardness from 5553 ppm to 317 ppm due to CaC03 precipitation, thereby reducing the Ca concentration from 2224 ppm to 126 ppm.

Masters of Science / This study was conducted to investigate hydrogeochemical processes controlling the evolution of groundwater chemistry and their influence on water quality in the Heuningnes Catchment. The role or influence of hydrogeochemical processes in groundwater quality in aquifer systems remains poorly understood. One of the ways of improving such understanding is to employ different techniques to explore key processes that govern groundwater quality in aquifer systems. Therefore, the present study investigated hydrogeochemical processes of groundwater resources and identified key processes that explained its quality from a spatiotemporal perspective. The quantitative approach that provides the ability to assess relationships between variables both spatially and temporally was applied. Groundwater sampling was done on four occasions during July 2017, October 2017, March 2018, and July 2018. Identification of hydrogeochemical processes controlling the evolution of groundwater chemistry and quality was done using various complementary tools. These tools included classification of the main water types, evaluation of water-rock interaction by means of stoichiometry analysis and bivariate correlation plots, inverse geochemical modelling, and statistical analysis (hierarchical cluster analysis and factor analysis). Physical parameters were measured in situ, while water samples were collected from boreholes, piezometers, springs, and artesian boreholes for laboratory analysis for major ions analysis. Descriptive and bivariate statistical methods were used to summarise and evaluate the strength of the relationship between variables, while multivariate statistical methods were applied to group similar samples based on their chemical compositions. Tri linear Piper diagrams were generated to characterize water type based on double normalizing the proportions of cations and anions, while correlation and stoichiometric analysis were applied to identify hydrogeochemical processes influencing groundwater chemistry. The results generated from the trilinear Piper diagrams confirmed the dominance of sodium and chloride ions in waters of the Heuningnes Catchment. Groundwater of a Na/Cl type is typical for a coastal aquifer characterised by saline, deep ancient groundwater. The lower parts of the Catchment were characterised by saline groundwater. The results indicated that shallow groundwater samples within the study area were more mineralised as compared to deep groundwater with EC values ranging between 20.8 and 2990 mS/m, with waters within the Table Mountain Group region (TMG), recording the lowest values. Deep groundwater for boreholes and artesian boreholes located upstream in the Catchment was fresh and yielded some of the lowest EC values recorded with an EC value below 50 mS/m. Generally, EC values increased from the upper TMG region of the Catchment towards the Bokkeveld shale region downstream and were highest during the dry season of 2018. The results indicated strong geological influences on water chemistry. Bivariate correlation and stoichiometric analysis identified cation exchange, adsorption, evaporation, weathering of carbonates, sulphates and silicate minerals as processes influencing the chemistry of groundwater in the Heuningnes Catchment. The Saturation Index (SI) results showed a change of calcite, dolomite, aragonite, gypsum, anhydrite, halite, melantinterite, siderite and sylvite from being undersaturated to oversaturated at some areas for the different seasons along the flow path. The mass-balance modelling results indicated that ion exchange and reverse ion exchange processes were more dominant at low elevations along the same flow path during the dry periods. However, at high elevations along the flow path, silicate weathering was the dominant process taking place. The findings of this study demonstrated the influence of hydrogeochemical processes in changing the water chemistry along the flow paths. In conclusion, the study showed the value of utilising various assessment tools as complementary techniques to improve the understanding about hydrogeochemical processes, and its influence on evolution of groundwater chemistry and quality. Based on the findings of the study the following recommendations were made for future studies; the sample points or sample boreholes in the study Catchment should be increased; and to have more sampling trips to enable better comparison between the possible processes

The integration of advanced technologies into existing water treatment facilities (WTFs) can improve and enhance water quality; however, these same modifications or improvements may adversely affect finished water provided to the consumer by public water systems (PWSs) that embrace these advanced technologies. Process modification or improvements may unintentionally impact compliance with the provisions of the United States Environmental Protection Agency’s (USEPA’s) Safe Drinking Water Act (SDWA). This is especially true with respect to corrosion control, since minor changes in water quality can affect metal release. Changes in metal release can have a direct impact on a water purveyor’s compliance with the SDWA’s Lead and Copper Rule (LCR). In 2010, the Town of Jupiter (Town) decommissioned its ageing lime softening (LS) plant and integrated a nanofiltration (NF) plant into their WTF. The removal of the LS process subsequently decreased the pH in the existing reverse osmosis (RO) clearwell, leaving only RO permeate and anion exchange (AX) effluent to blend. The Town believed that the RO-AX blend was corrosive in nature and that blending with NF permeate would alleviate their concern. Consequently, a portion of the NF permeate stream was to be split between the existing RO-AX clearwell and a newly constructed NF primary clearwell. The Town requested that the University of Central Florida (UCF) conduct research evaluating how to mitigate negative impacts that may result from changing water quality, should the Town place its AX into ready-reserve. iv The research presented in this document was focused on the evaluation of corrosion control alternatives for the Town, and was segmented into two major components: 1. The first component of the research studied internal corrosion within the existing RO clearwell and appurtenances of the Town’s WTF, should the Town place the AX process on standby. Research related to WTF in-plant corrosion control focused on blending NF and RO permeate, forming a new intermediate blend, and pH-adjusting the resulting mixture to reduce corrosion in the RO clearwell. 2. The second component was implemented with respect to the Town’s potable water distribution system. The distribution system corrosion control research evaluated various phosphate-based corrosion inhibitors to determine their effectiveness in reducing mild steel, lead and copper release in order to maintain the Town’s continual compliance with the LCR. The primary objective of the in-plant corrosion control research was to determine the appropriate ratio of RO to NF permeate and the pH necessary to reduce corrosion in the RO clearwell. In this research, the Langelier saturation index (LSI) was the corrosion index used to evaluate the stability of RO:NF blends. Results indicated that a pH-adjusted blend consisting of 70% RO and 30% NF permeate at 8.8-8.9 pH units would produce an LSI of +0.1, theoretically protecting the RO clearwell from corrosion. The primary objective of the distribution system corrosion control component of the research was to identify a corrosion control inhibitor that would further reduce lead and v copper metal release observed in the Town’s distribution system to below their respective action limits (ALs) as defined in the LCR. Six alternative inhibitors composed of various orthophosphate and polyphosphate (ortho:poly) ratios were evaluated sequentially using a corrosion control test apparatus. The apparatus was designed to house mild steel, lead and copper coupons used for weight loss analysis, as well as mild steel, lead solder and copper electrodes used for linear polarization analysis. One side of the apparatus, referred to as the “control condition,” was fed potable water that did not contain the corrosion inhibitor, while the other side of the corrosion apparatus, termed the “test condition,” was fed potable water that had been dosed with a corrosion inhibitor. Corrosion rate measurements were taken twice per weekday, and water quality was measured twice per week. Inhibitor evaluations were conducted over a span of 55 to 56 days, varying with each inhibitor. Coupons and electrodes were pre-corroded to simulate existing distribution system conditions. Water flow to the apparatus was controlled with an on/off timer to represent variations in the system and homes. Inhibitor comparisons were made based on their effectiveness at reducing lead and copper release after chemical addition. Based on the results obtained from the assessment of corrosion inhibitors for distribution system corrosion control, it appears that Inhibitors 1 and 3 were more successful in reducing lead corrosion rates, and each of these inhibitors reduced copper corrosion rates. Also, it is recommended that consideration be given to use of a redundant single-loop duplicate test apparatus in lieu of a double rack corrosion control test apparatus in experiments where pre-corrosion phases are vi implemented. This recommendation is offered because statistically, the control versus test double loop may not provide relevance in data analysis. The use of the Wilcoxon signed ranks test comparing the initial pre-corroding phase to the inhibitor effectiveness phase has proven to be a more useful analytical method for corrosion studies.

No description available.

Glass production has historically occurred at around 50 glassworks in Sweden, in a region known as the Kingdom of Crystals (Glasriket). Today, most of these sites are no longer active and left behind is glass waste of different forms (both as fragments of finished glass as well as unrefined glass melts). Consequently, increased concentrations of different metals, especially arsenic, lead and cadmium, have been found around the sites, both in soil as well as in ground and surface water. Between 2016 and 2019, the Geological Survey of Sweden (SGU) assigned Golder Associates AB (Golder) to evaluate the environmental risks at three different glassworks: Flerohopp, Åryd and Alsterbro. The results, based on humidity cell tests (HCT) conducted on glass samples from each site, showed that glass itself leached to a surprisingly high extent. Based on this, the aim of this master thesis has been to explain trends in glass leaching by a thorough literature review and through the analysis of HCT data of glass samples. Additionally, the speciation of different metals in the leachate was investigated based on geochemical modelling using PHREEQC. Results from the literature review show that one of the possible mechanisms for the leaching of glass in contact with water is ion exchange, which occurs at the surface of the glass, namely between glass components and H+ ions in water. Additionally, the literature also argues that glass with higher silica content form a more resilient structure, in contrast to glass which contains a large amount of modifiers, such as Na and Ca. Researchers speculate that adding such modifiers to the glass mass opens up the structure, making it more vulnerable upon contact with water. Looking at the total concentration of elements from the three glassworks, the results show a variation in silica content in relation to other elements. In line with this hypothesis, the sample from Åryd, which contained a higher proportion of modifiers, showed a high leaching rate of both Na and Si. Furthermore, the result shows that the leaching of Na and As follows the same pattern over the HCT period for all glassworks. This is, to some extent, also the case for Pb although the correlation is not as significant. This could be explained by the result from geochemical modelling, showing that As tends to dissolve into the leachate while Pb is more prone to forming secondary minerals. Hence explaining their differences in leaching behavior. The result from this study showed no clear correlation between Ca and either As or Pb which could potentially be explained by the formation of precipitates. However, another approach to describe the difference in the behavior between Na and Ca is based on the glass structure itself as well as the hypothesis that Na+ participate in ion exchange to a larger extent than Ca2+. Consequently, the leaching of Na+ makes the surface structure more vulnerable, thereby promoting the leaching of other components such as As and Pb. / Produktion av glas har historiskt skett på cirka 50 glasbruk i Sverige i ett område som kallas Glasriket. I dag är produktionen vid majoriteten av dessa glasbruk avvecklad och kvar på platserna finns glasavfall i olika former, både som skärvor av färdigt glas och som ej färdigställd glasmassa. Som en konsekvens av detta har förhöjda halter av olika metaller, särskilt arsenik, bly och kadmium, påträffats i jorden såväl som i grund- och ytvattnet kring glasbruken. Mellan åren 2016 och 2019 gav Sveriges geologiska undersökning (SGU) i uppdrag till Golder Associates AB (Golder) att uträtta huvudstudier och bedömma risker vid tre olika glasbruk, Flerohopp, Åryd och Alsterbro. Resultaten, baserade på fuktkammarförsök på glassavfall, påvisade att glas lakade till en överraskande hög utsträckning. Detta resultat lade grunden till detta examensarbete med frågeställningar i syfte att förklara lakning av glas baserat på en genomgående litteraturstudie samt analys av resultat från fuktkammarförsöken. Vidare har även geokemisk modellering med programmet PHREEQC gjorts för att identifiera olika specifieringar av metaller som kan förväntas påträffas i lakvätskan. Resultat från litteraturstudien visar att en möjlig process som kan förklara lakning av glas vid kontakt med vatten är jonbyte mellan glasets beståndsdelar och H+-jonerna i vattnet. Tidigare studier påvisar att ett högre kiselinnehåll i glaset skapar en mer motståndskraftig struktur än glas som innehåller en förhållandevis hög andel modifierare, såom Na och Ca. Forskare spekularar kring huruvida tillsatsen av modifierare till glasmassan bidrar till att öppna upp glasstrukturen och som en konsekvens av detta göra strukturen mer sårbar. Vid analys av prover tagna vid de tre olika glasbruken påvisade resultaten ett varierat kiselinnehåll i förhållande till övriga ämnen. I linje med denna hypotes påvisade provet från Åryd den högsta andelen modifierare och samtidigt även den högsta lakningen av Na såväl som Si. Vidare påvisar resultatet att lakningen av Na och As följer samma mönster över hela fuktkammarförsöket. Detta kan delvis ses för Pb men korrelationen är inte lika signifikant som för As. En förklaring till detta baseras på resultat från geokemisk modellering, där As tenderar att gå i lösning medan Pb kan förväntas forma sekundära mineral vilket därmed kan antas kontrollera lakningen. Resultatet från denna studie visade ingen korrelation mellan varken Ca och As eller Ca och Pb vilket också skulle kunna förklaras av utfällningar i form av Ca-mineral i lakvätskan. En annan utgångspunkt för att beskriva den skillnad som kan ses mellan Na och Ca baseras på själva glasstrukturen och hur Na+ deltar i jonbyte till en högre grad än vad Ca2+ gör. Som en konsekvens av detta bidrar lakningen av Na+ till att ytan på glaset blir mer sårbar och på så sätt gör att ämnen som As och Pb blir mer lättåtkomliga. Detta resulterar i en större möjlighet för dessa att delta i reaktioner på ytan och därmed laka ut från strukturen.