Conselho Nacional de Desenvolvimento Científico e Tecnológico / The distribution of pig slurry in agricultural areas, by presenting various elements in its composition, can over time, increase the levels of nutrients in the soil, as well as changing the distribution of chemical species in the soil solution. The study aimed to evaluate the levels of P, Cu and Zn total, available, soluble and the distribution of chemical species in solution, along the profile of a Hapludalf subject the application of 19 and 21 applications pig slurry and growing plants. The work was performed on soil columns of undisturbed soil, derived from an experiment conducted for 8 years in the experimental unit of the Federal University of Santa Maria (UFSM), Santa Maria (RS). The soil was a Typic Hapludalf, subjected to 0, 20, 40 and 80 m3 ha-1 of pig slurry applications. Soil samples were taken before and after the crops of black oat and corn in the greenhouse, in layers the 0-5, 5-10, 10-20, 20-30, 30-40 and 40-60 cm for the determining the levels of total P, Cu and Zn, available and extraction solution. In the solution were determined the concentration of the major cations, anions, dissolved organic carbon (DOC) and pH. The distribution of chemical species of P, Zn and Cu were obtained by computer program Visual Minteq. The 21 applications of pig slurry increased the levels of P, Cu and Zn total available and the solution in the surface layers with increasing doses. In addition to the increases in surface, successive applications of pig slurry increased the levels of depth, especially in larger doses, showing the migration of elements in the soil profile. High concentrations of soluble forms and available increase the risk of environmental contamination, promote transfers by both runoff and leaching, and increase the bioavailability and can cause toxicity of Cu and Zn to plants and microorganisms. The applications of pig slurry induced variations in the distribution of chemical species of P, Cu and Zn in soil solution, mainly in the surface layers, increasing the percentage of species of P complexed with Ca and Mg and reducing the proportion complexed with Al, these layers also increased the proportion of species of Cu and Zn complexed with organic and inorganic ligands, reducing the proportion of free species which are preferentially absorbed. The presence of plants leads to changes in the distribution of chemical species of P, Cu and Zn in soil solution, increasing the proportion of species of free P and reducing Cu and Zn. Thereby keeping soils under application of cultured pig slurry increases the proportion of P capable of absorbing and reduces risk of toxicity Cu and Zn. / A distribuição de dejetos líquidos de suínos em áreas agrícolas, por apresentar vários elementos em sua composição, pode ao longo do tempo, incrementar os teores de nutrientes no solo, bem como alterar a distribuição das espécies químicas na solução do solo. O trabalho objetivou avaliar os teores de P, Cu e Zn totais, disponíveis, solúveis e a distribuição das espécies químicas na solução ao longo do perfil de um Argissolo submetido a 19 e 21 aplicações de dejetos líquidos de suínos e ao cultivo de plantas. O trabalho foi realizado em colunas de solo com estrutura indeformada, derivadas de um experimento conduzido durante 8 anos, na unidade experimental da Universidade Federal de Santa Maria (UFSM), em Santa Maria (RS). O solo foi um Argissolo Vermelho Distrófico arênico, submetido a aplicações de 0, 20, 40 e 80 m3 ha-1 de dejetos líquidos de suínos. Foram realizadas coletas de solos antes e após as reaplicações dos tratamentos e cultivo de aveia preta e milho em casa de vegetação, nas camadas de 0-5, 5-10, 10-20, 20-30, 30-40 e 40-60 cm, para a determinação dos teores de P, Cu e Zn disponíveis, totais e extração da solução do solo. Na solução foi determinada a concentração dos principais cátions, ânions, carbono orgânico dissolvido (COD) e pH. A distribuição das espécies químicas de P, Cu e Zn foram obtidas através do programa computacional Visual Minteq. As 21 aplicações de dejetos líquidos de suínos incrementaram os teores de P, Cu e Zn totais, disponíveis e na solução nas camadas superficiais com o aumento das doses. Além dos incrementos em superfície, as sucessivas aplicações de dejetos líquidos de suínos incrementaram os teores em profundidade, principalmente nas maiores doses, evidenciando a migração dos elementos no perfil do solo. Altas concentrações de formas disponíveis e solúveis potencializam o risco de contaminação ambiental, por favorecer as transferências tanto por escoamento superficial como por lixiviação, além de aumentar a biodisponibilidade, podendo causar toxidez de Cu e Zn as plantas e aos microrganismos. As aplicações de dejetos líquidos de suínos promoveram alterações na distribuição das espécies químicas de P, Cu e Zn na solução do solo, principalmente nas camadas superficiais, aumentando a porcentagem das espécies de P complexadas com Ca e Mg e reduzindo a proporção complexada com Al, nestas camadas também incrementou a proporção das espécies de Cu e Zn complexadas com ligantes orgânicos e inorgânicos, reduzindo a proporção das espécies livres que são preferencialmente absorvidas. A presença de plantas promove alteração na distribuição das espécies químicas de P, Cu e Zn na solução do solo, aumentando a proporção das espécies livres de P e reduzindo as de Cu e Zn. Assim, manter solos submetidos à aplicação de dejetos líquidos de suínos cultivados aumenta a proporção de P passível de absorção e reduz o risco de toxidez por Cu e Zn.

Per- and polyfluoroalkyl substances (PFASs) have drawn great attention recently, due to their environmental persistence, potential toxicity and global distribution. PFAS is a large family of substances, characterized by a perflourinated carbon chain and a functional group. All PFASs are synthetic and have been widely used since the 1950s due to their unique properties of being both hydrophobic and oleophobic, making them useful for many industries. To be able to predict the fate of PFASs in the environment and to obtain detailed understanding of the transport processes, their partitioning behavior between soil particles and water depending on a range of parameters must be investigated. The aims of this study was to investigate the effects of pH, cation composition, functional group and perfluorocarbon chain length on sorption of PFASs to soil particles, by batch sorption experiment in laboratory scale. The laboratory-scale experiments were combined with modelling of the net charge to evaluate if net charge is a good predictor for sorption of PFASs to soil particles. 14 PFASs of varying length and functional groups were studied (PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnDA, PFDoDA, PFTeDA, PFBS, PFHxS, PFOS and FOSA). The effect on sorption of Na+, Ca2+ (two different concentrations) and Al3+ were investigated at pH-range 3-6. Modelling of net charge was carried out in the geochemical model Visual MINTEQ. The soil had 45% organic carbon content. The adsorption of PFASs was strongly correlated with perfluorocarbon chain length, showing a stronger adsorption to particles with increasing perfluorocarbon chain length (i.e. more hydrophobic). The relation between sorption (represented by the distribution coefficient log Kd) and perfluorocarbon chain length was linear for all PFSAs and C3 to C10 PFCAs. The PFSAs (sulfonate functional group) sorbed stronger to soil particles than the PFCAs (carboxylic functional group), and FOSA (sulfonamide functional group) sorbed the strongest. For most PFCAs, (C5-C13) there was a trend of decreasing log Kd (i.e. decreased sorption) with increasing pH, due to pH-dependent changes of the soil particle surfaces. For short and intermediate perfluorocarbon chain length PFCAs (C5-C8) and for PFHxS among the PFSAs, cations had a clear effect on sorption. Aluminium ions (trivalent, Al(NO3)3) had the largest effect, followed by calcium (divalent, Ca(NO3)2) where higher concentration resulted in stronger sorption. Sodium (univalent, NaNO3) had the least influence on sorption. The net charge modelled with Visual MINTEQ takes into account many parameters (including pH) that affect the surface charge and sorption of PFASs to soil particles. When comparing log Kd for the different PFASs with pH and net negative charge, net charge was a better predictor of sorption of PFASs to soil particles than solution pH alone. / Per- och polyfluoroalkylsubstanser (PFAS:er) har dragit stor uppmärksamhet till sig på senare tid, på grund av deras persistenta egenskaper, potentiella toxicitet och globala utbredning. PFAS är en stor grupp ämnen, kännetecknad av en perflourinerad kolkedja och en funktionell grupp. Alla PFAS är syntetiska och har använts i stor utsträckning sedan 1950-talet på grund av deras unika egenskaper av att vara både vatten- och fettavstötande, vilket gör dem användbara för många industriella tillämpningar. För att kunna förutsäga var dessa föroreningars hamnar i miljön och få mer detaljerad förstående för transportprocesserna, måste deras fördelningbeteende mellan jordpartiklar och vattenundersökas för en rad olika parametrar. Syftet med denna studie var att undersöka effekterna av förändrat pH, katjonsammansättning, funktionell grupp och perfluorkolkedjelängd på sorption av PFAS:er till jordpartiklar. Detta gjordes med sorptionsexperiment i laboratorieskala. Laboratorieexperimentet kompletterades med modellering av nettoladdning, för att se huruvida detta väl kunde förklara sorptionen till jordpartiklar. 14 PFAS:er av varierande längd och med tre olika funktionella grupper studerades (PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnDA, PFDoDA, PFTeDA, PFBS, PFHxS, PFOS och FOSA). Effekten på sorption av Na+, Ca2+ (två olika koncentrationer) och Al3+ undersöktes vid pH-intervallet 3-6. Modellering av nettoladdning utfördes i den geokemiska modellen Visual MINTEQ. Jorden som användes hade en halt av organiskt kol på 45%. Adsorptionen av PFAS:er var starkt positivt korrelerad med kedjelängden på de perfluorinerade kolkedjan. Ju längre kolkedja (dvs. mer hydrofob), desto starkare adsorption till partiklar. Relationen mellan sorptionen (här uttryckt som partitioneringskofficienten log Kd) och kedjelängd var linjär för alla PFSA och för C3 till C10 för PFCA. PFSA (sulfonat) adsorberade starkare än PFCA (karboxyl), och FOSA (sulfonamid) adsorberades starkast. För de flesta PFCA, (C5-C13) fanns en allmän trend där log Kd (dvs. sorption) minskade med ökande pH, på grund av pH-beroende förändringar på jordpartiklarna. För korta och medellånga PFCA (C5-C8) och för PFHxS hade katjonsammansättningen en tydlig effekt på sorptionen. Aluminiumjoner (trevärd, Al(NO3)3) hade den största effekten, följt av kalcium (tvåvärd, Ca(NO3)2) där den högre koncentrationen resulterade i starkare sorption. Natrium (envärd, NaNO3) hade minst påverkan på sorptionen till jordpartiklar. Visual MINTEQ tar hänsyn till många parametrar (inklusive pH), när nettoladdningen på jordpartiklarnas yta räknas ut. När log Kd för olika PFAS:er jämfördes med endera pH eller negativ nettoladdning, drogs slutsatsen att nettoladdning korrelerade bättre med sorption än pH.

Water resources in Florida have been severely degraded by eutrophic conditions, resulting toxic algae blooms, which negatively affect health and tourism. Eutrophication, or excessive amount of phosphorus (P) and nitrogen (N) in water, overstimulates the production of aquatic plants, depletes dissolved oxygen, and deteriorates the aquatic environment. However, phosphorus is a non-renewable resource essential for all living organisms. In fact, more than half of the total demand for P globally is to supply the food industry, which has concerningly accelerated the depletion rates of phosphate reserves. In many wastewater treatment plants (WWTPs), the enhanced biological phosphorus removal (EBPR) approach has been employed to achieve high phosphorus removals from wastewater through phosphate-accumulating organisms (PAOs). However, during either anaerobic or aerobic digestion of EBPR sludge, stored polyphosphates are released and carried into the sidestream, which is typically returned to the headworks of the main treatment facility, thereby recycling phosphorus back into the system. This treatment train is highly inefficient because nutrients rather are recirculated rather than recovered. Struvite (MgNH4PO4•6H2O) is precipitated in oversaturated aqueous solutions with equal molar concentrations of magnesium, ammonium, and phosphate. The controlled crystallization of struvite may be applied to remove phosphorus and some ammonium from sidestreams, which is the liquid portion of the digester effluent. Struvite can be employed as a sustainable slow-release fertilizer due to its low solubility in water. This offers the opportunity of marketing the struvite produced under controlled conditions and creating a revenue for the utility. The specific research objectives of this thesis are (1) to investigate different possible operating conditions under which anaerobically digested sludge from EBPR facilities might be treated through struvite precipitation; (2) to quantify the removal of N and P from sidestreams from anaerobically digested EBPR sludge via struvite precipitation and assess the composition of the precipitate obtained; and (3) to generate a cost analysis to assess the trade-offs between the capital and operation and maintenance (O&M) costs of struvite production and the benefits such as reduced chemical use and production of a slow-release fertilizer. The main parameters affecting struvite precipitation are the Mg2+ to PO43- molar ratio, pH, temperature, mixing speed, hydraulic retention time (HRT), and the seed quantity added to promote nucleation. Different operating conditions within these parameters were batch-tested as part of this study using sidestream from the pilot-scale anaerobic digester (AD) fed from Falkenburg Advanced Wastewater Treatment Plant (FAWWTP) EBPR sludge. Additionally, the effect of temperature and pH were investigated using Visual MINTEQ simulations. Analysis of Variance (ANOVA) was employed to investigate the variance within the removals from the centrate obtained for phosphate, ammonium, magnesium, and calcium. The chemical composition of the solids collected after employing the selected operating conditions was analyzed by powder X-ray diffraction (PXRD). The results for the batch tests performed as part of this thesis were quantified in terms of the removals of phosphate, ammonium, magnesium, and calcium from the centrate. The greatest amount of phosphate removal was achieved by operating the struvite reactor at 4.0 mmol of Mg2+ per mmole of PO43-. The other molar ratios tested were 1.0, 2.0, and 3.0. Visual inspection of the data showed significant variability in removals of ammonium, calcium, and magnesium, which are likely to be correlated with the highly variable influent concentrations into the struvite reactor. In this case, ANOVA will require larger data sets to accurately analyze variance in the results. The statistical results given by ANOVA for the pH suggests that the main species to contribute with struvite being precipitated are statistically stable within the tested pH values of 8.5, 9.0, and 9.5. The results obtained by the simulation using Visual MINTEQ indicated that maximum saturation as function of pH takes place at a pH between 9.5 and 10.0. The ANOVA for the mixing speed showed that significant amounts of ammonium were removed at higher mixing speeds. This is likely due ammonium being volatilized, which is enhanced by turbulence. Magnesium and phosphate showed lower removals at higher mixing speeds, suggesting that too high mixing speeds will promote struvite seed dissolution. ANOVA identified NH4+ and Ca2+ as the species significantly impacted by modifying the HRT from 8 to 20 minutes. This suggests that prolonged HRT promotes inorganic nitrogen species to volatilize. It is likely that at higher HRT, tricalcium phosphates (TCP) or other favored calcium species coprecipitated together with struvite. Regarding the added struvite seed for nucleation, the greatest removals of ammonium, magnesium, and, phosphate were observed when 1g/L of struvite seed was added. The results also indicated that adding 5 and 10 g/L was an excessive amount of seed, which ended up contributing significantly to more nutrients into the centrate rather than precipitating them. The results also suggested that the struvite crystals formed in the sidestream by secondary nucleation, since removals close to zero were reached after adding no seed. The optimum temperature identified by the simulation in Visual MINTEQ was 21°C. Operating the struvite reactor under the optimal conditions identified in the batch tests, resulted in an average of 99% total P (TP) and 17% total N (TN) removals. The precipitate molar composition for [Mg2+:NH4+:PO43-] was equal to [2:2:1] based on the concentrations that disappeared from the aqueous solution, suggesting that other minerals coprecipitated with struvite. Visual MINTEQ predicted that together with struvite, CaHPO4 and CaHPO4•2H2O will also precipitate under the tested conditions. However, given the obtained ratio it is likely that other unpredicted species by Visual MINTEQ, such as magnesium carbonates or magnesium hydroxide coprecipitated with struvite. PXRD analysis also revealed that the sample was likely contaminated struvite, although the specific contaminants were not identified. A cost analysis was performed to distinguish the economic feasibility of incorporating a struvite harvesting system to treat the anaerobically digested sidestream from the Biosolids Management Facility (BMF) within the Northwest Regional Water Reclamation Facility (NWRWRF). Three different scenarios were evaluated; in Scenario (1) Ostara® Nutrient Recovery Technologies Inc. (Ostara®) evaluated the production of struvite from anaerobically digested EBPR sidestream using a fluidized reactor. In Scenario (2), Ostara® evaluated the production of struvite in a fluidized bed reactor by employing Waste Activated Sludge Stripping to Remove Internal Phosphorus (WASSTRIP™) in a mixture of post-anaerobic digestion centrate and pre-digester thickener liquor. Scenario (3) was addressed by Schwing Bioset Inc. (SBI) for a continuously-stirred reactor followed by a struvite harvesting system. Scenario (2) offers the highest TP and TN recoveries through WASSTRIP™ release due to the additional mass of phosphorus that is sent to the phosphorus recovery process. Therefore, although Scenario (2) has the highest total capital costs ($5M) it also has the shortest payback period (18 years). Scenarios (1) and Scenario (3) have similar payback periods (22-23 years) but very different total capital costs. The annual savings by producing struvite in Scenario (3) is $40K, which is about 30% less than producing struvite in Scenario (1). This is probably because the only savings considered under Scenario (3) were the lower alum usage and the fertilizer revenue; however, the savings by producing class A biosolids, were not accounted for. Consequently, the reduced total capital cost of $960K and the annual payment amount per interest period close to $80K, positioned Scenario (3) as the more feasible one, considering 20 years as the expected life of the asset at a 5% interest rate.

As a consequence of rising uranium prices an interest in Sweden’s U deposits has emerged. This raises the important question of the possible environmental impacts of U mining operations. One of the most significant and serious issues is the contamination of groundwater by U following mining activities. The processes of uranium release and subsequent transport in groundwater is closely tied to its aqueous chemistry i.e. aqueous speciation, adsorption to mineral surfaces and dissolved organic carbon (DOM). The chemical parameters exerting the most control over these processes are pH and redox potential. The redox potential plays a decisive role because it controls the solubility of uraninite, a common uranium mineral and ore in Sweden’s bedrock deposits. Thus, by gaining insight into how changing redox conditions affect uraninite solubility, assessments can be made in order to estimate the extent of uranium transport by groundwater. Therefore the effects of the redox po-tential on U mobility will be examined in this work by means of computer modeling in the geochemical software VISUAL MINTEQ 3.0. The composition of the water used for modeling resembled that of a typical bedrock groundwater of Northern Sweden in the areas above the highest coastline. The simulations were carried out under different redox potentials at different pH levels in the presence of ferrihydrite and DOM to include the effects of U adsorption. The results show that the redox potential at which the uraninite mineral dissolves varies depending on the pH of the groundwater. From pH 4.0 to 7.5 the redox potential at which uraninite oxidizes decreases from 240-250 mV to 50-60 mV. This means higher redox conditions are needed for the dissolution of uraninite at low pH. Additionally, it is further concluded that the adsorption of U to ferrihydrite and DOC is important at pH 5-8 and pH < 7 respectively, which therefore play an important role in controlling the mobility of U in the modeled groundwater.

Löslighet och transport av sällsynta jordartsmetaller i Källfallsfältets gruvsandsmagasin Hugo de Campos Pereira Syftet med detta arbete har varit att kartlägga vilka mekanismer som styr lösligheten av sällsynta jordartsmetaller (eng. rare earth elements, REE) i sulfidhaltig anrikningssand vid den föredetta gruvan Källfallsfältet i Västmanland. För syftet har markvatten- och grundvattenprovtagning utförts, tillsammans med laktester och geokemisk modellering med Visual MINTEQ ver. 3.0. Resultaten visade att sulfidvittring är den främsta processen som styr pH i anrikningssanden, och därmed också indirekt REEs löslighet. Däremot är sulfidvittring ingen källa till REE i sig då ämnena inte föreligger sulfidbundna, något som oxiderat tillgänglighetstest NT ENVIR 006 visade. Istället går REE ut i lösning i anrikningssanden genom vittring av lättvittrade silikatmineral. Vanligtvis betraktas metall bunden i silikatform inte som geokemiskt aktiv. Jämförelser mellan laktester med olika jämviktstid visade att en kinetisk (tidsberoende) faktor föreligger, kopplad till nämnda silikatvittring, som påverkar pH och således också metallöslighet vid laktester på anrikningssanden. Vid jämförelse mellan laktester och halter i anrikningssandens mark- och grundvatten bör denna därmed vägas in. Det pH-statiska laktestet SIS-CEN/TS 14997 visade begränsad möjlighet att undersöka kinetik med anledning av att det utförs under förhållandevis kort tid, 48 timmar. REE- och Cu-halter vid syratitrering (de behandlingar med lägst syratillsatser) och enstegslakning (SIS-CEN ISO/TS 21268-2:2010) visade god, respektive förhållandevis god, överensstämmelse med uppmätta markvattenhalter. Detta visade att syratitrering och enstegslakning är laktest som är tillämpbara, respektive förhållandevis väl tillämpbara, för att uppskatta markvattenhalter i anrikningssanden. Specieringsmodellering med Visual MINTEQ ver. 3.0 visade att pH och DOC är de viktigaste parametrarna som styr REEs speciering i anrikningssandens mark-, grund och ytvatten. Samtliga REE bildar starka komplex med löst organiskt material, men koncentrationerna av DOC var generellt sett låga. I sura sulfatrika mark-, grund och ytvatten domineras specieringen av lösta sulfatkomplex, huvudsakligen (REE)SO4+, följt av fria hydratiserade joner som näst vanligaste förekomstform. Dessa resultat överensstämmer väl med tidigare modelleringsstudier av REEs speciering i sura sulfatrika vatten resulterande från gruvavfall. Med bakgrund av detta och av att REEs ekotoxicitet verkar överensstämma med den fria jon-modellen (eng. free ion model) förväntas REE uppvisa högre toxicitet vid låga pH-värden. / Solubility and transport of rare earth elements in the mine tailings of Källfallsfältet Hugo de Campos Pereira The mechanisms which govern the solubility of rare earth elements (REEs) in sulfide-containing tailings at the former mine site of Källfallsfältet (Västmanland, Sweden) were studied by the means of soil water and ground water sampling, leaching tests and geochemical modeling using Visual MINTEQ ver. 3.0. The results showed that weathering of sulfides is the primary process governing pH in the tailings, and thus also REE solubility. However, weathering of sulfides is no source for REE in itself since the elements are not bound in sulfides, which the oxidized availability test NT ENVIR 006 showed. Instead REE are released into solution by weathering of easily weathered silicates. Usually, metal bound in silicate form is not considered geochemically active. A kinetic (time dependent) factor, associated with the weathering of silicates, was found to affect pH and thus also metal solubility in leaching tests performed on the tailings. The standardized pH static leaching test (SIS-CEN/TS 14997) showed limitations in observing kinetic effects because of its relatively short equilibration time (48 h). Thus, in future studies with similar materials, leaching test kinetics should be taken into account when comparing leached concentrations with field measured concentrations. Acid titration and one step batch test (SIS-CEN ISO/TS 21268-2:2010) proved to be applicable and relatively well applicable to the tailings, respectively, in order to estimate soil solution concentrations. Speciation calculations using Visual MINTEQ ver. 3.0 showed that pH and DOC concentration are the most important factors which affect REE speciation in soil solution, ground water and surface water associated with the tailings. In acid sulfate rich solutions, low in DOC, speciation is dominated by sulfate complexes, mainly (REE)SO4+, followed by free dissolved ions as the second most common form. These results are in accordance with previous modeling studies of REE speciation in acid sulfate rich waters resulting from tailings. This, together with previous results showing that REE ecotoxicity seems to follow the free ion model, implies that the toxicity of the elements is expected to increase with decreasing pH value.