Indirect potable reuse has been practiced with the potential to enhance sustainability of water resources if planned accordingly. Depending on the pretreatment implemented for potable reuse, emerging contaminants; such as pharmaceuticals, personal care products, industrial solvents, bacterial/viral pathogens, and disinfection byproducts, might be present in source water and difficult to remove via various water treatment technologies. Low molecular weight organic compounds are especially challenging to remove and may require treatment optimization. The overarching purpose of this study was to demonstrate the feasibility of a carbon-based advanced treatment train; including ozonation, biological activated carbon (BAC) filtration and granular activated carbon (GAC) adsorption to achieve water quality suitable for potable reuse and assess the impact of a range of operating conditions for emerging contaminant removal at pilot-scale. The results from this study showed that carbon-based treatment train is equally effective as more commonly used, and more costly, membrane-based treatment trains in terms of pathogen and disinfection byproduct removal. A multiple-barrier approach was implemented, with each treatment stage capable of removing total organic carbon (TOC). GAC was responsible for removal of most of the TOC and emerging contaminants and this removal depended on the number of bed volumes of water processed by GAC. Empty bed contact time was another factor that dictated the extent of TOC removal in the BAC and GAC units as the carbon media was exhausted. Among the emerging contaminants detected, sucralose, iohexol and acesulfame-k were present in the highest concentrations in the influent and were detected consistently in the GAC effluent, thus making them good indicators of treatment performance. Apart from organics removal, BAC played an important role in removal of nutrients, such as ammonia via nitrification. N-Nitrosodimethlyamine (NDMA) was formed in the treatment process by ozone, but was shown to be effectively removed by BAC. EBCT, temperature, ozone dose and presence of pre-oxidants, such as monochloramine, played an important role in determining the amount of NDMA removed. These factors can be further optimized to improve NDMA removal. Sodium bisulfite was used for dechlorinating monochloramine residual post ozone. Nitrification in the BAC was shown to be inhibited by excess of sodium bisulfite dose. Thus monochloramine residual needs to be dechlorinated with sodium bisulfite to help with NDMA degradation but at the same time the sodium bisulfite dose needs to be monitored to allow complete nitrification in the BAC. 1,4-dioxane, another contaminant of emerging concern, was monitored in the treatment process. Biodegradation of 1,4-dioxane was enhanced via addition of tetrahydrofuran as a growth substrate. Biodegradation of 1,4-dioxane can help reduce energy and capital costs associated with advanced oxidation processes that are currently used for 1,4-dioxane removal. Further, relying on biodegradation for the removal of 1,4-dioxane can help avoid the formation of disinfection byproducts associated with advanced oxidation processes such as ozone with peroxide or ultraviolet disinfection with peroxide. The results from this project can be useful for designing potable reuse treatment trains and provide a baseline for removal of organic carbon and emerging contaminants. The conventionally used reverse osmosis and ultrafiltration approach is useful for organics removal in areas where the rationale behind potable reuse is water scarcity. Operational difficulties encountered during this study can prove to be important as this treatment process is scaled up to treat a total of 120 MGD of water for managed aquifer recharge. Overall the lessons learnt from this study can give a better understanding of a carbon-based treatment and further the advancement of reuse projects that have drivers other than water scarcity. / Doctor of Philosophy / The increased growth in urban areas has been accompanied by an increase in potable water demand, leading to depletion of surface and groundwater. Further, the discharge of nutrients such as nitrogen and phosphorus into some of these water bodies can lead to algal blooms. Water reuse involves treating used water and discharging into either a surface or groundwater body. Water reuse has been sought after as a solution to prevent these nutrients being discharged into surface water and to provide a sustainable solution for depletion of water sources. Direct or indirect potable reuse can include a combination of advanced treatment methods such as membrane filtration using ultrafiltration and reverse osmosis, biological filtration, granular or powdered activated carbon adsorption and disinfection methods such as ozonation and ultraviolet disinfection. This study focused on Hampton Roads Sanitation District's managed aquifer recharge project 'sustainable water initiative for tomorrow' (SWIFT), two different advanced water treatment strategies, namely carbon-based and membrane-based were implemented on a pilot-scale (20,000 L/day). The driver for indirect potable reuse in this study was not related to water shortage but aimed at reducing the nutrients discharged into the Chesapeake Bay. Other reasons for implementing reuse included recharging the depleting groundwater levels, land subsidence, and preventing flooding and seawater intrusion near the coastal areas. Membrane-based treatments, such as reverse osmosis, have been well established and studied for potable reuse. The less frequently used carbon-based treatment, that includes used of activated carbon for adsorption and biodegradation of organics (not involving any membrane barrier), was shown to be cost-effective and provided equal protection as that of the membrane-based system in terms of removal of pathogens. Further, since there is no membrane involved in the carbon-based treatment the energy requirements are less than that of the membrane-based treatment and concentrated brine solution is not produced, which makes it favorable for potable reuse where water scarcity is not an issue. This carbon-based treatment which included ozonation and activated carbon filtration and adsorption was further monitored and optimized for removal of organic contaminants and disinfection byproducts. Emerging contaminants such as pharmaceuticals, industrial solvents and personal care products can be harmful to human health and water ecology even at low concentrations. These contaminants are often present in wastewater effluent and can enter drinking water sources if untreated. These emerging contaminants were shown to be effectively removed by ozonation and granular activated carbon adsorption. The formation of disinfection byproducts such as N-nitrosodimethylamine in the treatment process and its removal in the biological activated carbon filtration was also monitored. The impact of temperature, presence of pre-oxidants and design factors such as ozone dose and empty bed contact time affected the removal of all these contaminants. This study provided an understanding of implementing carbon-based treatment for managed aquifer recharge for optimizing removal of bulk organic carbon and emerging contaminants. The results from this study can be utilized for designing advanced water treatment systems and can prove to be a guideline for monitoring and removing emerging contaminants.

This diploma thesis deals with the efficiency and factors affecting the adsorption of AOM (Algal Organic Matter) amino acids (AAs) arginine (Arg), phenylalanine (Phe) and aspartic acid (Asp) onto granular activated carbon (GAC) Picabiol 12x40 (PIC). The efficiency of AOM AAs removal was studied in laboratory equilibrium and kinetic experiments and it was shown that the adsorption efficiency of the selected AAs is dependent on the structure of the molecule of AAs and the nature of the functional groups of their side chain, and more particularly to solution pH, which determines the nature and size and surface charge of AAs and GAC. In contrast to this, the ionic strength (IS) of solution had relatively low effect on the AAs adsorption. Arg adsorption efficiency increased with increasing pH and reached a maximum at pH 9, where AAs and GAC were oppositely charged, and this leads to attractive electrostatic interactions. In the case of Asp adsorption on PIC practically did not work. The reason is that under all experimental conditions Asp molecules and the surface of the PIC carried identical negative charge. This led to the strong electrostatic repulsion between Asp and PIC which prevented effective adsorption. In the case of Phe the adsorption decreases with increasing pH. Maximum adsorption...

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-07-26T18:05:15Z No. of bitstreams: 1 2017 - Albiane Carvalho Dias.pdf: 1710937 bytes, checksum: 54d2634d67d97d4c119e2aa8507ca99b (MD5) / Made available in DSpace on 2017-07-26T18:05:15Z (GMT). No. of bitstreams: 1 2017 - Albiane Carvalho Dias.pdf: 1710937 bytes, checksum: 54d2634d67d97d4c119e2aa8507ca99b (MD5) Previous issue date: 2017-02-23 / CAPES / The inappropriate management of leachate can cause negative environmental impacts, in order to compromise the availability and quality of natural resources, reason of to their complex composition and high polluter potential. One of the alternatives for the treatment of landfill leachate is its combined treatment with domestic sewage in sewage treatment plants, although higher proportions of the leachate in the sewage could compromise the efficiency of the process. This study aimed to evaluate the efficiency of the combined treatment of landfill leachate and domestic sewage in biomass and activated carbon systems. For this, were used sequential batch reactors in lab-scale and two types of activated carbon - granular (GAC) and pulverized (PAC). The work consisted of two stages, among them they are: the tests where the reactors were fed with different mixtures of leachate/synthetic sewage (0, 2, 5 e 10%) and concentrations of GAC (0, 2, 4 e 6 g/L) operating with residence times 23h and sludge ages 28 days; and tests where the reactors were fed with a mixture of 5% leachate/sewage; fixed a PAC concentration of 6 g/L and were operated on with differents HRT of 23, 16 and 8 hours and sludge ages of 28, 28, and 17 days, respectively. It has been evaluated, the difference between the two types of carbon regarding COD removal efficiency, in the following configurations: fixing the concentration of carbono (6 g/L) and the percentage of leachate in the feed (5% v/v), for the batch time of 23 h and sludge age of 28 d. For the first step, it was possible to verify that the COD removal efficiency was higher in the reactors containing GAC and biomass when comparedes to the reactor containing only biomass. And along this stage of the experiment it was possible to observe that after the increase of leachate concentration in the feed there was a significant drop in COD removal efficiency. In the evaluation of the PACT? process, it was verified that the reactor with HRT of 23 h was the one that presented the best COD and color removal efficiencies the process, 79 and 44%, respectively. In the comparative tests between the two types of carbon, the PAC system proved to be much more efficient in the removal of COD, presenting an average efficiency of 79% when compared to the GAC system (63%). / O gerenciamento inadequado do lixiviado pode causar impactos ambientais negativos, de forma a comprometer a disponibilidade e qualidade dos recursos naturais, devido sua composi??o complexa e seu elevado potencial poluidor. Uma das alternativas para o tratamento de lixiviado de aterros sanit?rios ? o seu tratamento combinado com esgoto dom?stico em esta??es de tratamento de esgoto, embora propor??es mais elevadas do lixiviado no esgoto possam comprometer a efici?ncia do processo. Este trabalho teve por objetivo avaliar a efici?ncia do tratamento combinado de lixiviado de aterro sanit?rio e esgoto dom?stico em sistemas com biomassa e carv?o ativado. Para isto, foram utilizados reatores em batelada sequencial em escala de laborat?rio e dois tipos de carv?o ativado- granular (CAG) e pulverizado (CAP). O trabalho foi constitu?do de duas etapas, dentre elas est?o: os ensaios onde os reatores foram alimentados com diferentes misturas de lixiviado/esgoto sint?tico (0, 2, 5 e 10%) e concentra??es de CAG (0, 2, 4 e 6 g/L) operando com tempos de resid?ncia de 23 h e idades do lodo de 28 dias; e ensaios onde os reatores foram alimentados com uma mistura de 5% de lixiviado/esgoto, fixado uma concentra??o de CAP de 6 g/L e foram operados com diferentes tempos de resid?ncia de 23, 16 e 8 horas e idades de lodo de 28, 28, e 17 dias, respectivamente. Avaliou-se, ainda, a diferen?a entre os dois tipos de carv?o quanto ? efici?ncia de remo??o de DQO, nas seguintes configura??es: fixando a concentra??o de carv?o (6 g/L) e o percentual de lixiviado na alimenta??o (5% v/v), para o tempo de batelada de 23 h e idade do lodo de 28 d. Para a primeira etapa, foi poss?vel verificar que a efici?ncia de remo??o de DQO foi superior nos reatores contendo CAG e biomassa quando comparados ao reator contendo apenas biomassa. E ao longo desta etapa do experimento foi poss?vel observar que ap?s o aumento da concentra??o de lixiviado na alimenta??o houve queda significativa na efici?ncia de remo??o de DQO. Na avalia??o do processo PACT?, verificou-se que o reator com tempo de resid?ncia de 23 h foi o que apresentou as melhores efici?ncias de remo??o de DQO e cor do processo, 79 e 44%, respectivamente. Nos testes comparativos entre os dois tipos de carv?o, o sistema com CAP mostrou-se muito mais eficiente na remo??o de DQO, apresentando efici?ncia m?dia de 79%, quando comparado ao sistema com CAG (63%).

This study evaluated the combination of ozone and granular activated carbon (GAC) treatment for the removal of sulfide and disinfection byproduct (DBP) precursors in drinking water at the pilot-scale. The research conducted was performed at the Auxiliary (Aux) and Main Water Treatment Plants (WTPs) in Sanford, Florida. Both WTPs rely upon groundwater sources that contain total sulfide ranging from 0.02 to 2.35 mg/L and total organic carbon (TOC) ranging from 0.61 to 2.20 mg/L. The Aux WTP’s raw water contains, on average, 88% more sulfide and 24% more TOC than the Main WTP. Haloacetic acids (HAA5) and total trihalomethanes (TTHMs) comprise the regulated forms of DBPs. HAA5 are consistently below the maximum contaminant level (MCL) of 60 μg/L, while TTHM ranges from 70 to 110 μg/L, at times exceeding the MCL of 80 μg/L in the distribution system. Ozone alone removed total sulfide and reduced UV-254 by about 60% at the Aux Plant and 35% at the Main Plant. Producing an ozone residual of 0.50 mg/L prevented the formation of bromate while removing approximately 35 to 60% concentration of DBP precursors as measured by UV-254. Operating the GAC unit at an empty bed contact time (EBCT) of 10 minutes for the Aux Plant and 5.5 minutes for the Main Plant resulted in 75% and 53% of UV-254 reduction, respectively. The average 120 hour TTHM formation potential for the Aux and Main Plants were 66 μg/L and 52 μg/L, respectively, after treatment by ozone and GAC. GAC exhaustion was deemed to have occurred after seven weeks for the Aux Plant and eleven weeks for the Main Plant. The GAC columns operated in three phases: an adsorption phase, a transitional phase, and a biologically activated carbon (BAC) phase. The GAC adsorption phase was found to produce the lowest TTHMs; however, TTHMs remained less than 80 μg/L during the BAC stage at each plant. BAC exhaustion did not occur iv during the course of this study. Ozone-GAC reduced chlorine demand by 73% for the Aux Plant and 10% for the Main Plant.

Formaldehyde is a ubiquitous and hazardous indoor air pollutant and reducing concentrations in indoor environments is a public health priority. The goals of this doctoral work were to advance analytical methods for continuous monitoring of formaldehyde at very low concentrations (sub-20 ppb[subscript v]) and to improve fundamental, mechanistic understanding of how structural and chemical properties of activated carbon influence removal of formaldehyde from indoor environments. To achieve these goals, emerging sensor-based technology was evaluated for its ability to detect and quantify ppb[subscript v]-level formaldehyde concentrations on a continuous basis at relative humidity levels characteristic of residential indoor environments. Also, a combination of spectroscopic and selective titration techniques was employed to characterize molecular-level structural and chemical properties of traditional and chemically treated granular activated carbon (GAC). In addition to selecting two different commercially available GACs for study, design and preparation of a laboratory-prepared, chemically treated GAC was pursued to create nitrogen-doped GAC with desirable surface chemical properties. Performance of all GACs was evaluated with respect to formaldehyde removal through a series of packed bed column studies. With respect to continuous formaldehyde monitoring, a method detection limit for emerging sensor technology was determined to be approximately 2 ppb[subscript v], and for relative humidity levels characteristic of indoor environments (> 40%), quantitative, continuous formaldehyde measurements less than 10 ppb[subscript v] were robust. The two commercially available GACs tested were both capable of removing formaldehyde; however, the GAC with greater density of basic surface functional groups and greater electron-donating potential (Centaur) removed twice as much formaldehyde (on a GAC mass basis) as the less basic GAC (BPL). A laboratory-prepared GAC (BPL-N) was successfully created to contain pyridinic and pyrrolic nitrogen, which was associated with increased surface density of basic functional groups, as well as with increased electron-donating potential. BPL-N exhibited better removal capacity for formaldehyde than BPL and Centaur. Furthermore, packed bed column studies of BPL-N and BPL formaldehyde removal performance yielded evidence to support the hypothesis that electron-donating potential, especially nitrogen functional groups at the BPL-N surface, promote catalytic removal of gas-phase formaldehyde via oxidation. / text

The technical feasibility of producing sulphur-impregnated activated carbons (SIACs) from high-sulphur fluid coke by chemical activation was investigated. Using KOH and SO2, the activation process was able to produce SIACs with controllable specific surface area (SBET), pore size distribution and sulphur content. The highest SBET was over 2500 m2/g and the highest sulphur content was 8.1 wt%. K-edge X-ray Absorption Near Edge Structure (XANES) spectroscopy was employed to characterize the sulphur in fluid cokes and SIACs. The results revealed that the sulphur on fluid coke surface was mainly in the form of organic sulphide and thiophene (total 91-95 %), in addition to some sulphate (5 - 9%). The study of KOH-treated fluid coke suggested that KOH was effective in converting organic sulphide and thiophene to water soluble inorganic species which were readily removed by acid and water washing. SO2 treatment of fluid coke added sulphur to fluid coke through SO2-carbon reaction. Elemental sulphur was the main product, while part of the thiophene, sulphide and sulphate in the raw coke remained in the product. In KOH-SO2 activation, disulphide, sulphide, sulphonate and sulphate were identified on SIAC surface; no thiophene was found, suggesting a complete removal of thiophene. Sulphur content in specific forms in SIACs was therefore controllable by varying the ratio of KOH, SO2 and fluid coke. SIACs produced from KOH-SO2 activation showed a comparable Hg2+ adsorption capacity (43 – 72 mg/g) with those reported in the literature (35-100 mg/g) and that of a commercial SIAC (41 mg/g). Although a larger SBET often resulted in a greater Hg2+ adsorption capacity, the benefit started to diminish when SBET was greater than about 1000 m2/g. A statistically significant and positive correlation was found between Hg2+ adsorption capacity and total sulphur content. Elemental sulphur and reduced sulphur were largely responsible for the enhanced Hg2+ adsorption.

During and after medical treatment, pharmaceutical compounds as well as their metabolites and conjugates are excreted from the users through urine and feces. The pharmaceuticals end up in wastewater treatment plants, which are not designed to deal with this kind of organic micro-pollutant. Eventually the pharmaceuticals end up in the environment where they can have adverse physiological and behavioral effects on aquatic life and could contribute to the spread of antibiotic resistance among microorganisms. Adsorption to activated carbon is an established method for removal of pharmaceuticals from wastewater. It is however quite expensive and it is of interest to identify cost-effective alternatives. One possible alternative is bark, which is a common by-product from forest industry and has a complex microstructure and high porosity compared to many other naturally occurring materials. In order to investigate the potential of using bark to remove pharmaceuticals from municipal wastewater four column filters were built, two with activated carbon and two with bark. They were used in an experiment conducted at Kungsängsverket, the largest wastewater treatment plant in Uppsala municipality. The objectives were to assess pharmaceutical concentrations in treated wastewater at Kungsängsverket and to compare the performance of bark and activated carbon filters under different loading rates. During this time the filters were run at different loading rates and two different types of bark was used. 24 common pharmaceuticals from different therapeutic groups were targeted. The pharmaceutical concentrations measured at Kungsängsverket were generally low, but mean concentrations of five pharmaceuticals (atenolol, metoprolol, furosemide, hydrochlorothizide and diclofenac) exceeded 250 ng/l. Out of these, four have been shown to have adverse effects on aquatic life and it would be preferable if they were not released into the recipient. Bark was not as good at removing pharmaceuticals from wastewater as activated carbon was, but decent removal rates were achieved for several compounds. The removal rates of either filter type did not seem to be significantly impacted by variations in loading rate or bark size. The concentrations of a few compounds increased after treatment with the bark filters and the reason for this is not clear. One possibility is interference from other organic substances in the wastewater or the bark, but determining the reason for this increase should be a priority for any further research on the subject. Another problem encountered during the project that is likely to pose a problem for future implementation is that the bark filters were very sensitive to clogging. Running the filters at full scale would require frequent back-washing which would be a disadvantage from both economical and practical reasons.

Les supercondensateurs à base de carbones activés sont caractérisés par une puissance et une cyclabilité supérieures à celles des batteries. Toutefois, en raison de leur faible densité d’énergie, ils sont principalement utilisés comme source de stockage secondaire. Les objectifs de cette thèse étaient d’augmenter l’énergie des supercondensateurs fonctionnant en milieu organique (TEABF4/AN) et de comprendre la répartition des ions dans les pores des carbones activés avant et après la charge des supercondensateurs. Deux approches ont été suivies pour répondre au premier objectif. D’abord nous avons cherché à augmenter la capacité volumique des carbones à 90 F/cm3. Parmi les carbones étudiés, un carbone a attiré notre attention en raison de sa densité d’électrode et de sa capacité élevées. Toutefois, un traitement thermique s’est avéré nécessaire pour réduire la fonctionnalité de surface altérant principalement les performances en vieillissement. Le carbone ainsi traité présente une capacité volumique de 88 F/cm3. Aussi, en s’appuyant sur le principe d’égalité des charges, nous avons mis en place plusieurs systèmes asymétriques carbone/carbone avec des masses et/ou des carbones différents aux deux électrodes. Les configurations optimales permettent de déplacer la fenêtre de stabilité vers des potentiels plus faibles. Les bonnes performances en vieillissement des systèmes asymétriques en masse réalisés au laboratoire nous ont encouragés à réaliser des essais préliminaires sur des composants industriels. Il a ainsi été montré que la dissymétrie de masse permet de ralentir le vieillissement à 2,7 V par rapport à un système symétrique standard. Les analyses RMN de la poudre d’électrodes imprégnées d’électrolyte montrent que les ions et le solvant occupent la porosité en l’absence de polarisation. L’étude des électrodes chargées a montré que les ions se réorganisent dans la porosité. A l’électrode négative, le solvant est exclu de la porosité et les ions TEA+ pénètrent sans leur sphère de solvatation. A l’électrode positive, il reste du solvant, ce qui suggère que les ions BF4 - sont partiellement solvatés dans la microporosité. En augmentant la tension de charge, la quantité d’ions TEA+ and BF4 - augmente respectivement dans les électrodes négative et positive; toutefois des contre-ions restent présents même à tension élevée. / Supercapacitors based on activated carbons are characterized by higher power and cycle life than batteries. Due to their low energy density, they are mainly used as secondary storage device. The objectives of this thesis were to improve the energy density of supercapacitors operating in organic electrolyte (TEABF4/AN) and to elucidate the distribution of ions in the pores of activated carbons, before and after the charge of supercapacitors. Two approaches were followed to reach the first objective. First, it has been attempted to increase the volumetric capacitance up to 90 F/cm3. One carbon giving a high electrode density and capacitance, but having a high amount of oxygenated functionalities, has been identified. It was thermally treated under reducing atmosphere to depress the functionalities which negatively impact the ageing of supercapacitors. The post-treated carbon displayed a volumetric capacitance of 88 F/cm3. Asymmetric carbon/carbon supercapacitors, with different mass or/and different carbons for the electrodes, were constructed for shifting the stability window towards lower potential values. Laboratory cells built in these conditions exhibited promising performance during cycling, which encouraged us to confirm the results at industrial scale. In particular, the asymmetric configuration using electrodes of different mass showed better ageing behavior at 2.7 V that the symmetric system. RMN analysis of the powder from electrodes soaked with the organic electrolyte showed that the solvent and ionic species are already confined into the micropores without applying any polarisation. During charging, the solvent molecules are expelled from the porosity of the negative electrode while TEA+ ions penetrate into the pores without their solvation shell. On the contrary, the presence of some solvent together with BF4 - in the positive electrode indicates that the BF4 - ions are partially solvated. Upon increasing the voltage, the amount of TEA+ and BF4 - increases in the negative and positive electrode, respectively; however, counter ions are still present even at high voltage.

<p>Mercury (Hg) is a globally circulating heavy metal released through both natural and anthropogenic sources. The largest anthropogenic source of mercury to the global atmosphere is artisanal and small-scale gold mining (ASGM). During the ASGM process, miners add elemental mercury to large quantities of sediment or soil in order to create gold-mercury amalgams that separate alluvial gold from the remaining geological host material. Miners then heat the amalgam using a blowtorch or similar device to separate the mercury and gold, exposing themselves to mercury vapor and releasing mercury to the environment. Following amalgam heating, mercury can deposit into aquatic ecosystems. There, anaerobic microorganisms can convert mercury to methylmercury (MeHg), a potent neurotoxin that rapidly accumulates in aquatic food webs. A high concentration of MeHg in fish poses serious human health risks, especially to pregnant women and children. </p><p>In Peru’s Region of Madre de Dios (MDD), mercury use for ASGM is widespread due to increasing global demand for gold. This region in the tropical Amazon is one of the world’s most biodiverse ecosystems and home to more than 150,000 Indigenous and non-Indigenous people, 40% of whom live below the poverty level. Recently, people living in the region have become more aware of negative impacts of Hg pollution through popular press. However, there is lack of controlled scientific studies to examine the environmental impacts of Hg from ASGM and subsequent exposures to surrounding communities. </p><p>This dissertation addresses four questions in order to better understand how mercury from ASGM impacts environmental health in Madre de Dios: (1) How is mercury distributed along the Madre de Dios River in areas of active ASGM activity, and what is the risk for mercury exposure to downstream communities? (2) How does land use change associated with ASGM activity affect soil-mediated mercury transport in the Colorado River, Madre de Dios, Peru? (3) Can sulfurized carbon be manufactured in a feasible way for developing countries and used to capture mercury during ASGM amalgam burning? (4) What is the mercury methylation potential of easy-to-manufacture spent, sulfurized carbon sorbents?</p><p>Despite significant information on the direct health impacts of mercury to ASGM miners, the impact of mercury contamination on downstream communities has not been well characterized, particularly in Madre de Dios. In this area, ASGM has increased significantly since 2000 and has led to substantial political and social controversy. The second chapter of this dissertation examines the spatial distribution and transport of mercury through the Madre de Dios River with distance from ASGM activity. It also characterizes risks for dietary mercury exposure to local residents who depend on fish from the river. River sediment, suspended solids from the water column, and fish samples were collected in 2013 at 62 sites near 17 communities over a 560 km stretch of the Madre de Dios River and its major tributaries. In areas downstream of know ASGM activity, mercury concentrations in sediment, suspended solids and fish within the Madre de Dios River were elevated relative to locations upstream of mining. Fish tissue mercury concentrations were observed at levels representing a public health threat, with greater than one-third of carnivorous fish exceeding the international health standard of 0.5 mg/kg. This research demonstrates that communities located hundreds of kilometers downstream of ASGM activity, including children and indigenous populations who may not be involved in mining, are at risk of dietary mercury exposure that exceed acceptable body burdens. </p><p>This research involved extensive field sampling in an active mining region and indicated suspended particulate transport may be an important source of mercury from mining areas to downstream communities. Chapter three of this research focused on understanding how land use changes can influence soil and sediment transport from mining regions. Within the MDD, a large portion of mining in concentrated within the Colorado River watershed. In the Colorado River watershed, mining and deforestation have increased dramatically since the 1980s, largely concentrated in the Puquiri subwatershed. Field sampling in Feb 2015 identified a strong correlation between Hg and suspended solids concentrations, with especially high suspended solids concentrations downstream of ASGM activity. This supported the hypothesis that Mercury transport in this region is facilitated by soil mobilization and runoff. In order to understand how ASGM activity in the Puquiri affects sediment mobilization from the watershed over time, we employed a watershed-scale soil mobilization model using satellite imagery from 1986 to 2014. The model estimated that soil mobilization in the Colorado River watershed increased by 2.5 times during the time period, and increased by six times in the Puquiri subwatershed, leading to between 10 and 60 kg of mercury mobilized in 2014. If deforestation continues at its current exponential rate through 2030, soil and heavy metal mobilization may increase by five times. This research shows that deforestation associated with ASGM in the Colorado River watershed can exacerbate soil mobilization and mercury contamination. While the impacts of mercury and deforestation are often considered separately, here we studied how deforestation associated with ASGM in the Madre de Dios region can significantly increase soil mobilization and mercury transport to downstream communities.</p><p>With a substantial portion of mercury releases coming from a non-industrialized process in developing countries, low-cost and low-tech mercury capture is becoming increasingly necessary. While impregnated activated carbon sorbents are well studied for mercury-capture in developed countries and large industrialized settings, there exist few suitable low-cost alternatives for mercury capture from artisanal and small-scale gold mining (ASGM) in developing countries. Chapter four sought to develop an easy-to-manufacture carbon sorbent using elemental sulfur and activated carbon or hardwood-based biochar for potential use during ASGM gold-amalgam heating. Consumer-grade sulfur powder was melted on granular activated carbon or hardwood biochar in a process feasible for a cook stove setting. Activated carbon and biochar were successfully sulfurized to more than 5% sulfur by weight using powdered, elemental sulfur. The sorbent products were tested for elemental mercury sorption from an air gas stream at room temperature. The sulfurized activated carbon achieved higher elemental mercury adsorption capacity in air stream (500 μg Hg m-3, 2 L min-2) relative to unsulfurized activated carbon and sulfurized biochar. Sorption isotherms were used to examine the sorption mechanism, and indicated that likely a pseudo first order reaction was occurring. This research provides a possible option for mercury control by modifying established mercury capture technologies to be easy to manufacture, locally available, and less hazardous to produce.</p><p>In Chapter 5 of this research, the sulfurized sorbents were examined further to understand methylation potential in sediment slurries. Anaerobic sediment slurries were constructed to examine methylmercury (MeHg) production of spent sorbents. Five sorbent types with approximately 10 mg/kg Hg each were added to slurries at 5 % by mass. Dissolved mercury was used as a control to simulate atmospheric deposition or highly reactive mercury. After a 5 d incubation at room temperature, MeHg production was ten times greater with low-technology sulfurized sorbents as compared to activated carbon or biochar alone. Sulfurized sorbents leached significantly more mercury than their non-sulfurized counterparts during desorption experiments and led to greater dissolved mercury concentrations. This research shows that low-cost mercury-contaminated sorbents can have unintended consequences with increased MeHg production and potential for more harm to local communities than atmospheric release.</p><p>Mercury releases from ASGM are expected to grow, leading to higher concentrations of mercury in the atmosphere that may affect ecosystems throughout the globe. Understanding the importance of mercury from ASGM to toxicity and accumulation requires in depth research on mercury transformations and MeHg production associated with ASGM. This research examines mercury distribution and transport from ASGM active regions. It identifies that deforestation, erosion, and particulate transport play important roles in overall mercury transport, leading to hazardous mercury concentrations downstream of ASGM activity. Effective point-of-use mercury capture technologies would dramatically decrease the mass of mercury released to the environment. The final chapters of this research serve as a proof of concept for using sulfurized activated carbon for mercury capture in developing countries. </p><p>Our research team has built strong relationships with several governmental and non-governmental organizations in Peru who will aid in distributing information. This research will provide invaluable environmental health information to residents, inform political intervention, and reveal a new potential avenue for low-cost mercury control.</p> / Dissertation

Les vapeurs organiques émises des solvants utilisés dans le produit chimique / la nourriture / les processus pharmaceutiques, ou des stations d'entreposage de combustible d'hydrocarbure aux terminus de pétrole, peuvent être efficacement capturées par l'adsorption sur les lits de charbon actif. L'objectif général du programme de recherche est les études expérimentales et les études de simulation de l'adsorption et des pas de régénération en cas de l'enlèvement COV qui estime dans les émissions industrielles par l'Adsorption (TSA – Température Swing Adsorption et VTSA -Vacuum Température Swing Adsorption). C'est accompli par les points suivants : établir les données d'équilibre d'isotherme pour 5 COV et 8 carbones activés à 293, 313, 333 et 353 K (complètement 120 expériences d'isotherme) et les utiliser ensuite dans le modèle de simulation; développer une simulation pose pour le processus de régénération et l'adsorption; concevoir et optimiser l' expérimentale de TSA qui a été établi dans Ecole des les Mines de Nantes; concevoir et optimiser l'expérimentale de VTSA qui a été établi dans GRL ARKEMA; la validation de simulation de résultats expérimentaux de le processus TSA et VTSA. Une fois après l'achèvement de tous les objectifs, le but est de se développer et le lancement un utile de simulation complet pour l'adsorption et les pas de régénération de COV avec la coopération de la Société PROSIM. / Organic vapors emitted from solvents used in chemical / food / pharmaceutical processes, or from hydrocarbon fuel storage stations at oil terminals, can be efficiently captured by adsorption onto activated carbon beds. The overall objective of the research program is the experimental and simulation studies of the adsorption and regeneration steps in the case of VOC removal which accounts into industrial emissions by Temperature Swing Adsorption (TSA) and Vacuum Temperature Swing Adsorption (VTSA) processes. This is achieved by the following steps : to establish the isotherm equilibrium data for 5 VOCs and 8 activated carbons at 293, 313, 333, and 353 K (totally 120 isotherm experiments) and then use them in the simulation model; to develop a simulation model for adsorption and regeneration process; to design and optimize the experimental setup of Thermal Swing Adsorption (TSA) which has been established in Ecole des Mines de Nantes; to design and optimize the experimental setup of Vacuum Temperature Swing Adsorption processes (VTSA) which has been established in GRL ARKEMA unit ; simulation validation of experimental results of TSA and VTSA process. Once after the completion of all the objectives, the goal is to develop and launch a complete simulation package for adsorption and regeneration steps of VOCs with the co-operation from PROSIM Corporation.