A cana-de-açúcar, matéria-prima para a produção de açúcar cristal, é uma das maiores e mais antigas culturas agrícolas exploradas no mundo. O Brasil se destaca como maior produtor de açúcar cristal do mundo, exportando grande parte de sua produção, sendo a indústria de refrigerantes um dos maiores consumidores. No entanto, a composição química do açúcar pode conter inúmeros compostos que promovem a formação de flocos ácidos (ABF), reduzindo a aceitação do produto ao consumidor. Para o açúcar de beterrada o principal composto apontado como precursor dos ABF é a saponina, no entanto não há indícios da relação desse composto para os flocos de açúcar de cana-de-açúcar. A elucidação da característica química dos ABF foi alvo de inúmeros estudos, no entanto, nenhum outro estudo científico coordenou diversas especialidades técnicas no intuito de desmistificar a ampla composição química dos ABF de açúcar de cana-de-açúcar. Este estudo teve como objetivo identificar a composição química utilizando diferentes técnicas analíticas, tais como, métodos histoquímicos em microscopia ótica, microscopia de varredura acoplada a espectroscopia de energia dispersiva (MEV/EDS) e espectrometria de massas (Q-ToF e MALDI-MS). Inicialmente foram analisadas 10 tipos de açúcar cristal, quanto a sua composição e formação de flocos ácidos, a fim de correlacionar esses dois parâmetros e os resultados mostraram que todas as amostras de açúcar analisadas apresentaram a formação de flocos, sendo que os parâmetros que mais se relacionaram à sua formação foram a Cor ICUMSA, turbidez e compostos fenólicos. Posteriormente, utilizou-se resina de adsorção optiporeSD-2 para avaliar a retiradas de compostos indesejáveis presentes no açúcar que levam a formação dos ABF, e foi possível observar a eficiência da resina na retirada de compostos que formam os flocos, bem como na retirada de compostos coloridos do xarope de açúcar. A avaliação química dos flocos mostrou que eles são formados por compostos de diferentes classes químicas, uma vez que pelas análises histoquímicas, foi possível observar a presença de tecidos celulares da cana-de-açúcar, tais como, xilema, epiderme, estômatos e parênquimas, na constituição dos flocos ácidos. Os compostos minerais detectados, em maior proporção, pelas análises em MEV/EDS foram silício, alumínio, enxofre e ferro. Através das análises em Q-ToF e MALDI-MS foi possível identificar compostos como p-hidroxibenzaldeído, vanilina, ácido triacontanóico, ácido hexadecanóico, ácido n-octadecanóico e ácido octacosanóico na composição dos flocos. Estes compostos são encontrados em tecidos vegetias, confirmando que os flocos ácidos são formados por partículas de células vegetais de cana-de-açúcar que não são totalmente removidas durante o tratamento do caldo e acabam aderidas ao cristal de sacarose. Confirmando que não há relação entre os ABF e o composto da saponina. Para as análises microbiológicas não houve a detecção de micro-organismos na composição dos flocos analisados. Por fim o pH foi o parâmetro que mais ifluenciou na formação dos ABF. / Sugarcane, the raw material for the production of crystal sugar, is one of the largest and oldest agricultural crops in the world. Brazil stands out as the largest producer of crystal sugar in the world, exporting much of its production to the soft drinks. However, the chemical composition of sugar may contain numerous compounds that promote the formation of acid beverage flocs (ABF), reducing product acceptance. For beet sugar the main compound indicated as precursor of the ABF is saponin, however there are no indications of the relation of this compound to the sugar cane ABF. The elucidation of the chemical characteristics of the ABF has been the subject of numerous studies, however, no other scientific study has coordinated several technical specialties in order to demystify the broad chemical composition of the cane sugar ABF. Initially 10 types of crystal sugar were analyzed for their composition and formation of ABF in order to correlate these two parameters and the results showed that all the sugar samples analyzed presented the formation of ABF, and the parameters that were most related to its formation were the ICUMSA Color, turbidity and phenolic compounds. Subsequently, optipore SD-2 adsorption resin was used to evaluate the removal of undesirable compounds present in the sugar that lead to the formation of ABF, and it was possible to observe the efficiency of the resin in the withdrawal of compounds that form the ABF, as well as in the removal of colored sugar syrup compounds. he chemical evaluation of the ABF showed that they are formed by compounds of different chemical classes, since by histochemical analyzes, it was possible to observe the presence of sugarcane cell tissues, such as xylem, epidermis, stomata and parenchyma, In the constitution of the ABF. The mineral compounds detected, to a greater extent, by the SEM / EDS analysis were silicon, aluminum, sulfur and iron. Through the analyzes in Q-ToF and MALDI-MS it was possible to identify compounds such as p-hydroxybenzaldehyde, vanillin, triacontanic acid, hexadecanoic acid, n-octadecanoic acid and octacosanoic acid in the composition of ABF. These compounds are found in vegetative tissues, confirming that the ABF are formed by particles of sugarcane plant cells that are not totally removed during the treatment of the broth and end up adhered to the sucrose crystal. Confirming that there is no relationship between the ABF and the saponin compound. For the microbiological analyzes, there was no detection of microorganisms in the analyzed ABF composition. Finally, pH was the parameter that most influenced the formation of ABF.

The introduction of the Enhanced Actinide Removal Plant (EARP) at Sellafield in 1994 was designed to decontaminate radioactive effluents produced during nuclear fuel reprocessing. Through the action of flocculation with iron, followed by filtration, the effluents are decontaminated before being discharging to sea. The plant has been in successful operation for the past 20 years, and has made a significant difference to the level of radioactivity of the waste. However, little is known about the formed flocs. Particular concern focuses around future changes to the effluent compositions to be processed through EARP. These future feeds will potentially contain significantly less iron, thus potentially impacting upon the flocculation process and the efficiency of the decontamination process. The effluents currently treated contain significant concentrations of iron, stemming from the Magnox fuel reprocessing plant, along with actinides, fission and corrosion products. The flocculation of these acidic radioactive ferric feeds results in the formation of solid iron hydroxide flocs with encapsulated radioactivity. The flocs are then filtered, encapsulated and stored. It is envisioned that by characterising the floc properties, both physically and chemically a greater understanding of EARP can be obtained, ultimately leading to a maintained process efficiency with alternative feed compositions. The effect of a reduction in iron concentration on the chemical and physical properties of the flocs has been studied. The presence of any iron in the mock effluents was found to beneficially increase the contaminant decontamination factors (DF). However, the efficacy of this increase varied between contaminates. The DFs of group I and II metals ranged from 7.10 to 1.19 while lead ranged from 4x105 to 1.60, dependent upon iron concentration. Transition metal and lanthanide contaminants were marginally affected. With the use of agar embedding, the 'liquid form' of the flocs has been retained for two and three dimensional observations. SEM/EDX analysis has allowed for the inspection and chemical characterisation of the flocs while 2D microscope image analysis has allowed for the study of floc size and shape. A range of diameters, 300 - 1500 micro metre were found. Three dimensional X-ray Computer Tomography (3D X-ray CT) conducted at the Manchester X-ray Imaging Facility (MXIF) has led to the physical characterisation and classification of the flocs. Further, by studying the 3D shape it has been possible to classify a floc as a granule, fibre, chip or blade according to the Zingg classification with the majority of formed flocs being classified as granules.

Batch sedimentation is a method that enables us to understand the mechanism of compaction and compression of sedimenting slurry. However, batch settling behaviour is a very complex phenomenon that is not easily described fully by a mathematical model. This causes unrealistically large empirical calculations when the thickener size estimations are required. Channelling, reverse concentration gradients and the initial concentration of the slurry have large effects on batch settling. Existing procedures do not provide clear relationships involving these three significant variables. In this study, batch sedimentation phenomena are examined in detail and possible explanations are given to clarify the complex behaviour using recent theories. Modern research has shown that channelling is an unwanted formation because channels can change the concentration at the bottom and top of the bed by carrying a great amount of flocs upwards. Batch sedimentation tests were performed using flocculated slurry of Calcium Carbonate at various initial concentrations such as 250 g/l, 500 g/l, 750 g/l and 1000 g/l to observe channelling and reverse concentration gradients. Flux plots for the batch system reveal behaviour which can be attributed to the upward flow of solids. In addition, photographic methods were used to observe settling processes, channelling mechanisms and flocs in the channels. One of the purposes of this work was to examine the phenomenological solid-liquid separation theory of Buscall and White (1987), which employs the material properties of the local volume fraction, compressive yield stress Py ()ö and hindered settling function R()ö to identify the material behaviour in batch sedimentation. Stepped-pressure filtration and batch settling tests were used to measure the material characteristics for the flocculated CaCO3 suspension. Experimental data were demonstrated using Height versus Time and Height versus Concentration graphs and displayed the possible region of reverse concentration gradients and channelling in the settling bed. Mathematical predictions adopted from Usher (2002) were performed employing material characteristics of the material and graphical documentations were presented. The results of mathematical predictions were compared to the experimental results and the modes of sedimentation explained by Lester et al. (2005). Fundamental theoretical models and experimental observations highlight that the main driving force for channelling is the high-pressure gradient at the bottom of the bed and the most important factors that cause channelling are high initial concentration of slurry and settling time. The predictions also show that the material and flocculant used for the batch settling tests demonstrate important effect on the settling process. The knowledge and information gained from this study is valuable to maximize the thickening process.

Activated sludge treatment systems rely on a microbial consortium structurally organized in bioflocs to treat pollutants present in wastewater. The treatment process efficiency in these systems can be severely affected by toxic chemicals present in the influent wastewater. The effects of chemical toxins at the treatment process level are determined by the mechanisms that occur at the biofloc and cellular levels, which can be physical, chemical and physiological in nature. We believe that the overall process effects of chemical toxins on activated sludge systems likely result from a combination of all three types of mechanisms and that they are interdependent, in the sense that specific bacterial stress response mechanisms (physiological mechanisms that protect the cell from toxic conditions) may lead to physical/chemical alterations at the floc level, and vice-versa. Ultimately, understanding the mechanisms that occur at the floc and metabolic scales will help to design more robust and efficient treatment systems, and to develop tools to prevent and mitigate the effects of toxic chemicals on activated sludge systems. In this research, we set out to establish the link between the effects of chemical toxins on activated sludge cultures at the process, floc and metabolic scales. First, the effects of shock loads of different toxic sources (1-chloro-2,4-dinitrobenzene (CDNB), cadmium, 1-octanol, 2,4-dinitrophenol (DNP), weakly complexed cyanide, pH 5, 9 and 11, and high ammonia levels) on activated sludge process parameters (biomass growth, respiration rate, flocculation, chemical oxygen demand (COD) removal, dewaterability and settleability) were studied. For all chemical shocks except ammonia and pH, concentrations that caused 15, 25 and 50% respiration inhibition were used to provide a single pulse chemical shock to sequencing batch reactor (SBR) systems containing a nitrifying (10 day solids retention time – SRT) and a non-nitrifying (2 day SRT) biomass. We found that cadmium and pH 11 shocks were the conditions that most detrimentally affected all the processes, followed by CDNB. DNP and cyanide primarily led to effects on respiration, while pH 5, 9, octanol and various ammonia concentrations did not impact the treatment process to a significant extent. Additionally, there was a clear correlation between biomass deflocculation and increases in the effluent soluble COD of the shocked reactors for different chemical sources. With this study, we were able to establish a source-effect matrix linking classes of chemical toxins to their potential inhibitory effects on activated sludge processes, thereby contributing to a better understanding of the potential effects of toxic industrial discharges into biological treatment systems. The findings of the first phase of the research, specifically the correlation between chemical-induced deflocculation and increases in soluble COD, served as a motivation to explore the role of floc structure in the response of activated sludge cultures to toxic compounds, and to conduct a more in-depth analysis of the supernatant (soluble phase) of toxin-exposed activated sludge. In one study, we evaluated the respiration inhibition induced by octanol, cadmium, N-ethylmaleimide (NEM), cyanide and DNP on activated sludge biomasses with different floc structures but similar physiological characteristics, with the objective of assessing the role of the extracellular polymeric substances (EPS) in flocs as a protection barrier against chemical toxins. Mechanical shearing was applied to fresh mixed liquor to produce biomasses with different floc structure properties and specific oxygen uptake rate assays were conducted on the sheared and unsheared mixed liquors. The results showed that the respiration inhibition by octanol and cadmium was more intense in sheared mixed liquor (which had less EPS material available in the flocs and smaller floc sizes) than in the unsheared biomass. Conversely, the respiration inhibition induced by NEM and cyanide was similar for the different mixed liquors tested. These results allowed us to conclude that the EPS matrix functions as a protective barrier for the bacteria inside activated sludge flocs to chemicals that it has the potential to interact with, such as hydrophobic (octanol) and positively-charged (cadmium) compounds, but that the toxicity response for soluble, hydrophilic toxins (NEM and cyanide) is not significantly influenced by the presence of the polymer matrix. In the final study that was conducted, we used the metabolomics-based technique metabolic footprinting to assess if the soluble phase of mixed liquor exposed to different chemical toxins exhibited a toxin-specific biochemical composition. We hypothesized that toxin-specific effects could be distinguished through footprint patterns of those soluble samples. The impact of cadmium, DNP and NEM shock loads on the composition of the soluble fraction of activated sludge mixed liquor was analyzed by liquid chromatography-mass spectrometry (LC-MS). The results from this study indicated that there was a significant release of biomolecules (proteins, carbohydrates and humic acids) from the floc structure into the bulk liquid due to chemical stress. More importantly, using a multivariate statistical method called discriminant function analysis with genetic algorithm variable selection (GA-DFA), we were able to show that the soluble phase samples from the different reactors could be differentiated, thereby indicating that the footprints generated by LC-MS were different for the four conditions tested and, therefore, toxin-specific. These footprints, thus, contain information about specific biomolecular differences between the samples, and we found that only a limited number of m/z (mass to charge) ratios from the mass spectra data was needed to differentiate between the control and each chemical toxin-derived samples. In addition, since the experiments were conducted with mixed liquor from four distinct wastewater treatment plants, the discriminating m/z ratios may potentially be used as universal stress biomarkers. These results are promising and indicate that LC-MS may be used for the discovery of activated sludge stress biomarkers, to allow the development of new toxin detection technologies for prevention of upset events in activated sludge systems. / Ph. D.

The purpose of this research was to uncover factors responsible for the prolific growth of various filamentous microorganisms in the bulking activated sludge at the Hoechst Celanese wastewater treatment plant. First, futile attempts were made to isolate the filamentous bacterium, <i>Nostocoida limicola II</i>, from activated sludge for purposes of its characterization. Chemostat and batch experiments were also performed in an effort to determine conditions favoring its growth, but the filament’s growth could not be sustained in any of the conditions provided. Second, several CSTRs were operated in which single cationic concentrations were varied to try to isolate the actual effects of the different cations on activated sludge microorganisms. Though the objectives of these CSTR experiments were not accomplished because bulking conditions could not be maintained in the reactors, insight was gained as to possible factors significantly impacting filamentous growth. A full-scale study followed, in which microbial population shifts in the activated sludge at the Hoechst Celanese wastewater treatment plant were tracked with changes in the operating conditions at the plant. The results of this study suggested the existence of relationships between the abundances of certain filaments and DO concentration and/or F/M ratio in the activated sludge environment. To isolate the individual effects of these two factors on activated sludge microorganisms, two modified batch studies were performed. The results of these studies indicated that the growth of most of the filaments present in the Hoechst Celanese activated sludge is primarily affected by F/M ratio, though DO concentration strongly impacts the growth of some. The findings in the DO and F/M experiments were combined with the findings in the full-scale study to estimate DO concentration and/or F/M ratio ranges in which growth of the following activated sludge filamentous organisms may be favored: <i>Haliscomenobacter hydrossis</i>, <i>Microthrix parvicella</i>, <i>Nocardia species</i>, <i>Nostocoida limicola II</i>, and Types 0041, 0581, 1851, and 1863. / Master of Science

This research was designed to investigate the effect of cations on activated sludge characteristics and also to determine their influence on digestion performance. For this purpose, cations in solution and in floc were evaluated along with various activated sludge characteristics and the collected waste activated sludge underwent both anaerobic and aerobic digestion. It was found that large amounts of biopolymer (protein + polysaccharide) remained in the effluent of WWTP that received high influent sodium but had low iron and aluminum in floc. However, sludges from plants with high sodium and high iron and aluminum dewatered well and produced high quality effluents, suggesting that iron and aluminum have significant positive effects on floc properties. Following anaerobic digestion, a significant increase in solution protein occurred and correlations between solution protein, ammonium production, percentile volatile solids reduction and iron in floc were obtained. These data indicate that iron-linked protein is released to solution when iron is reduced and its degradation is responsible for volatile solids reduction in anaerobic digestion. In aerobic digestion, polysaccharide in solution increased along with calcium, magnesium and inorganic nitrogen. This implies that divalent cation-bound biopolymer might be the primary organic fraction that is degraded under aerobic digestion. Combined (anaerobic/aerobic) digestion was performed and produced further volatile solids destruction with discrete cation and biopolymer response during each phase of digestion. These results support the theory that two types of organic matter with different cation bindings are present in floc and each type is degraded under different digestion processes. / Master of Science

<p>Landfill leachate contains a variety of contaminants and is created when rainwater percolates the landfill. For landfill management the leachate is the main issue that can cause problems to the environment. At the landfill of Fläskebo, Renova AB treats the leachate in a local treatment plant. The treatment consists of a chemical treatment step with chemical precipitation, flocculation, sedimentation and filtration, and a final step with a carbon and peat filter. Renova has to ensure that the condition of the leachate reaches the regulation set for the landfill before it is released to the recipient. This regulation has not yet been established and a final suggestion will be given to the county administrative board in spring 2006.</p><p>In this master thesis the chemical treatment of Fläskebo is optimized. A comparison between the control program and the regulation was made to estimate the contamination of the leachate. Also the effectiveness of the two steps is evaluated. For optimization, the leachate was first tested in a laboratory with different coagulants and flocculants.</p><p>The purpose was to increase the precipitation of particles and metals; arsenic, cadmium, chromium, mercury, lead, copper, nickel and zinc through sweep floc coagulation and hydroxide precipitation. After the laboratory tests the precipitation was tested in the treatment plant with higher pH and coagulant. Also the process control for sodium hydroxide was examined.</p><p>The leachate had a small content of organic matter and nutrients, but had a large content of halogenated substances (AOX) and the heavy metals nickel and copper. High concentrations of contaminants were reduced better than low concentrations in the two treatment steps. The carbon and peat filter material also caused an increase of the arsenic content in the leachate after filtration. From the laboratory work the results showed a better reduction of metals with iron-chloride, PlusJÄRN and the anjonic polyacrylamid, Fennopol A. Because of the high content of chloride the iron- sulphate, PurFect was chosen for further tests. The optimal pH for the heavy metals arsenic, zinc, copper and nickel was between pH 9 and 9, 5. The precipitation in the treatment plant showed better results with sodium hydroxide and a higher pH, pH 9 in the flocculation basin. An increase of the coagulant PurFect from 202 mg/l to 225 mg/l meant only a higher chemical cost. The process control of sodium hydroxide showed an oscillating and unstable control performance, which may lead to a higher consumption of chemicals.</p> / <p>Lakvatten har varierande föroreningsgrad och karaktär och bildas då regnvatten perkolerar igenom en deponi. För en deponiverksamhet är lakvattnet den huvudsakliga påverkan på den omgivande miljön. Vid en av Renova ABs deponier, Fläskebo, utanför Göteborg sker reningen av vattnet i den lokala reningsanläggningen. Reningen består av kemisk fällning, flockning, sedimentering och filtrering samt ett kol- och torvfilter. För att få släppa ut lakvattnet har Renova just nu ett prövotidsvillkor på lakvattnets kvalité och till våren 2006 skall förslag på slutgiltiga utsläppsvillkor lämnas till Länsstyrelsen.</p><p>I detta examensarbete har den kemiska reningen av lakvattnet från Fläskebo optimerats utifrån lakvattnets karaktär. Lakvattnets föroreningsgrad bedömdes efter en jämförelse av analysresultatet inom kontrollprogrammet och riktvärdena i prövotidsvillkoret. Dessutom utvärderades effektiviteten i varje enskilt reningssteg, den kemiska reningen och kol- och torvfiltret. För optimering av den kemiska reningen testades lakvattnet först på lab med olika fällnings- och flockningsmedel. Uppgiften var att öka partikelfällningen och reducera metallerna arsenik, kadmium, krom, kvicksilver, bly, koppar, nickel och zink i lakvattnet genom svepkoagulering och hydroxidfällning.</p><p>Utifrån resultaten på lab testades sedan fällningen i full skala, pH höjdes i flockningsbassängen och så även dosen fällningsmedel till vattnet. En inledande undersökning av regleringen av lutdosering gjordes med några stegsvarsexperiment.</p><p>Lakvatten innehöll låga halter av organiskt material och närsalterna kväve och fosfor, medan de halogena ämnena (AOX) och tungmetallerna nickel och koppar var höga. De båda reningsstegen, kemisk rening och kol- och torvfiltret var generellt bra på att rena föroreningar i höga koncentrationer men var sämre vid låga. Kol- och torvfiltret ökade koncentrationen i vattnet av arsenik genom materialets interna läckage. I fällningsförsöken gav järnkloriden, PlusJÄRN och den anjoniska polyakrylamiden, Fennopol A bäst resultat i att avskilja metaller. Järnsulfaten PurFect gav näst bäst resultat och valdes istället för järnkloriden för vidare försök då kloridhalten i lakvattnet redan var högt. Optimalt pH för arsenik, zink, koppar och nickel var inom pHintervallet 9 och 9,5. Fällningen i full skala ute i verket visade ett bättre resultat vid tillsatt lut och ett högre pH (pH 9) i flockningsbassängen. Däremot betydde en höjning av fällningskemikalien från 202 mg/l PurFect till 225 mg/l enbart en ökad kemikaliekostnad och en överdosering. Det visade sig dessutom att lutregleringen var svängig och på gränsen till instabil. Regulatorn bör därför ses över så att risken för ökad kemikaliekonsumption och kostnader minskar.</p>

The surface charges of cellulosic fibers contribute to several papermaking operations that influence the manufacture and final properties of paper. This thesis investigates the effect of the surface charges on wet-end chemistry, e.g. through the interaction of cationic polyelectrolytes with the fiber surface charges, and on the network strength of pulp suspensions. The polyelectrolyte titration method was used to investigate the interaction of the fiber charges with cationic polyelectrolytes. Techniques were developed to fluorescent label the adsorbing cationic polyelectrolyte in order to visualize the adsorption behavior. Fluorescent confocal laser scanning microscopy (CLSM) was used to determine the extent to which the cationic polyelectrolyte adsorbs into the porous fiber wall. It was shown that the polyelectrolyte charge density limits the adsorption to the surface under electrolyte-free conditions. Adsorption into the fiber wall only occurs for two conditions: 1) if the molecular mass is sufficiently low or 2) the electrolyte concentration is high enough to screen the charges along the polyelectrolyte backbone but not the interactions between the polyelectrolyte and the fiber charges. Aside from the polyelectrolyte properties, the fiber charge density contributes to the adsorption behavior of cationic polyelectrolytes. The fiber charge profile was altered by bulk and surface carboxymethylation. The electrolyte concentration at which a deviation from 1:1 stoichiometry occurs was shown to be dependent on the amount of surface charges, such that the deviation in stoichiometry occurs at a higher electrolyte concentration for pulps having a higher surface charge. A hypothesis was developed to test the conditions at which the deviation in adsorption stoichiometry occurs, which was defined as the critical electrolyte concentration (CEC). It was found that the CEC corresponded to the electrolyte concentration at which the distance between the fiber charges was on the order of the Debye length. Electron spectroscopy for chemical analysis (ESCA) was used as an independent calibration procedure to validate for which a 1:1 stoichiometry occurs. The analysis with ESCA agreed well with the polyelectrolyte titration method for measurement of fiber surface charges. When measured under appropriate conditions, i.e. electrolyte concentration and molecular properties, the fiber surface charge can accurately be measured by the polyelectrolyte titration method. The charge profiles of various pulp types and treatments were also examined. Having been established as a valid technique, the polyelectrolyte titration method was again used to measure the surface charge while conductometric titration was used to measure the total charge content. The amount of bulk and surface charges vary depending on the pulping method and type of wood, although the ratio between the bulk and surface charge (i.e. the charge ratio) is similar for chemical pulps. The mechanical pulp has a higher charge ratio because it contains more fines material than chemical pulp. Bleaching of the chemical pulp decreases the amount of bulk and surface charges, although the charge ratio remains essentially constant. However, methods such as beating or carboxymethyl cellulose (CMC) grafting are available to increase the charge ratio. The effect of the charge profile on fiber-fiber interactions was studied on both a microscopic and macroscopic level. Colloidal probe microscopy (CPM) was used to investigate the microscopic interactions between two cellulose surfaces. Cellulose surfaces, prepared by spin-coating a dissolving pulp onto silica, were used to model the fiber surface, which is too rough for surface force measurements. The charge density of the model surface was increased by CMC grafting. Results showed that increasing the surface charge density created large electrosteric repulsions, due to CMC the chains protruding out from the surface. These interactions on the microscopic scale affect the fiber network strength, which was measured with a parallel plate rheometer. When the repulsion is increased between the fibers, caused by the increase in the surface charge, fiber flocs break apart more easily due to a reduced friction between the fiber surfaces. The forces acting on the fiber network can also be mechanical in origin. The fiber length and flexibility were altered in order to study the influence of mechanical surface linking and elastic fiber bending on the fiber network strength. Using the storage modulus (G’0) as a measure of fiber network strength, longer fibers were found to create a stronger network due to an increased amount of fiber contacts. Flexible fibers have a lower network strength than stiff fibers because the fibers come to rest in a less strained position such that the the influence of elastic fiber bending on the fiber network strength is predominant. / QC 20100831

Landfill leachate contains a variety of contaminants and is created when rainwater percolates the landfill. For landfill management the leachate is the main issue that can cause problems to the environment. At the landfill of Fläskebo, Renova AB treats the leachate in a local treatment plant. The treatment consists of a chemical treatment step with chemical precipitation, flocculation, sedimentation and filtration, and a final step with a carbon and peat filter. Renova has to ensure that the condition of the leachate reaches the regulation set for the landfill before it is released to the recipient. This regulation has not yet been established and a final suggestion will be given to the county administrative board in spring 2006. In this master thesis the chemical treatment of Fläskebo is optimized. A comparison between the control program and the regulation was made to estimate the contamination of the leachate. Also the effectiveness of the two steps is evaluated. For optimization, the leachate was first tested in a laboratory with different coagulants and flocculants. The purpose was to increase the precipitation of particles and metals; arsenic, cadmium, chromium, mercury, lead, copper, nickel and zinc through sweep floc coagulation and hydroxide precipitation. After the laboratory tests the precipitation was tested in the treatment plant with higher pH and coagulant. Also the process control for sodium hydroxide was examined. The leachate had a small content of organic matter and nutrients, but had a large content of halogenated substances (AOX) and the heavy metals nickel and copper. High concentrations of contaminants were reduced better than low concentrations in the two treatment steps. The carbon and peat filter material also caused an increase of the arsenic content in the leachate after filtration. From the laboratory work the results showed a better reduction of metals with iron-chloride, PlusJÄRN and the anjonic polyacrylamid, Fennopol A. Because of the high content of chloride the iron- sulphate, PurFect was chosen for further tests. The optimal pH for the heavy metals arsenic, zinc, copper and nickel was between pH 9 and 9, 5. The precipitation in the treatment plant showed better results with sodium hydroxide and a higher pH, pH 9 in the flocculation basin. An increase of the coagulant PurFect from 202 mg/l to 225 mg/l meant only a higher chemical cost. The process control of sodium hydroxide showed an oscillating and unstable control performance, which may lead to a higher consumption of chemicals. / Lakvatten har varierande föroreningsgrad och karaktär och bildas då regnvatten perkolerar igenom en deponi. För en deponiverksamhet är lakvattnet den huvudsakliga påverkan på den omgivande miljön. Vid en av Renova ABs deponier, Fläskebo, utanför Göteborg sker reningen av vattnet i den lokala reningsanläggningen. Reningen består av kemisk fällning, flockning, sedimentering och filtrering samt ett kol- och torvfilter. För att få släppa ut lakvattnet har Renova just nu ett prövotidsvillkor på lakvattnets kvalité och till våren 2006 skall förslag på slutgiltiga utsläppsvillkor lämnas till Länsstyrelsen. I detta examensarbete har den kemiska reningen av lakvattnet från Fläskebo optimerats utifrån lakvattnets karaktär. Lakvattnets föroreningsgrad bedömdes efter en jämförelse av analysresultatet inom kontrollprogrammet och riktvärdena i prövotidsvillkoret. Dessutom utvärderades effektiviteten i varje enskilt reningssteg, den kemiska reningen och kol- och torvfiltret. För optimering av den kemiska reningen testades lakvattnet först på lab med olika fällnings- och flockningsmedel. Uppgiften var att öka partikelfällningen och reducera metallerna arsenik, kadmium, krom, kvicksilver, bly, koppar, nickel och zink i lakvattnet genom svepkoagulering och hydroxidfällning. Utifrån resultaten på lab testades sedan fällningen i full skala, pH höjdes i flockningsbassängen och så även dosen fällningsmedel till vattnet. En inledande undersökning av regleringen av lutdosering gjordes med några stegsvarsexperiment. Lakvatten innehöll låga halter av organiskt material och närsalterna kväve och fosfor, medan de halogena ämnena (AOX) och tungmetallerna nickel och koppar var höga. De båda reningsstegen, kemisk rening och kol- och torvfiltret var generellt bra på att rena föroreningar i höga koncentrationer men var sämre vid låga. Kol- och torvfiltret ökade koncentrationen i vattnet av arsenik genom materialets interna läckage. I fällningsförsöken gav järnkloriden, PlusJÄRN och den anjoniska polyakrylamiden, Fennopol A bäst resultat i att avskilja metaller. Järnsulfaten PurFect gav näst bäst resultat och valdes istället för järnkloriden för vidare försök då kloridhalten i lakvattnet redan var högt. Optimalt pH för arsenik, zink, koppar och nickel var inom pHintervallet 9 och 9,5. Fällningen i full skala ute i verket visade ett bättre resultat vid tillsatt lut och ett högre pH (pH 9) i flockningsbassängen. Däremot betydde en höjning av fällningskemikalien från 202 mg/l PurFect till 225 mg/l enbart en ökad kemikaliekostnad och en överdosering. Det visade sig dessutom att lutregleringen var svängig och på gränsen till instabil. Regulatorn bör därför ses över så att risken för ökad kemikaliekonsumption och kostnader minskar.

The Everglades is a sub-tropical coastal wetland characterized among others by its hydrological features and deposits of peat. Formation and preservation of organic matter in soils and sediments in this wetland ecosystem is critical for its sustainability and hydrological processes are important divers in the origin, transport and fate of organic matter. With this in mind, organic matter dynamics in the greater Florida Everglades was studied though various organic geochemistry techniques, especially biomarkers, bulk and compound specific δ13C and δD isotope analysis. The main objectives were focused on how different hydrological regimes in this ecosystem control organic matter dynamics, such as the mobilization of particulate organic matter (POM) in freshwater marshes and estuaries, and how organic geochemistry techniques can be applied to reconstruct Everglades paleo-hydrology. For this purpose organic matter in typical vegetation, floc, surface soils, soil cores, and estuarine suspended particulates were characterized in samples selected along hydrological gradients in the Water Conservation Area 3, Shark River Slough and Taylor Slough. This research focused on three general themes: (1) Assessment of the environmental dynamics and source-specific particulate organic carbon export in a mangrove-dominated estuary. (2) Assessment of the origin, transport and fate of organic matter in freshwater marsh. (3) Assessment of historical changes in hydrological conditions in the Everglades (paleo-hydrology) though biomarkes and compound specific isotope analyses. This study reports the first estimate of particulate organic carbon loss from mangrove ecosystems in the Everglades, provides evidence for particulate organic matter transport with regards to the formation of ridge and slough landscapes in the Everglades, and demonstrates the applicability of the combined biomarker and compound-specific stable isotope approach as a means to generate paleohydrological data in wetlands. The data suggests that: (1) Carbon loss from mangrove estuaries is roughly split 50/50 between dissolved and particulate carbon; (2) hydrological remobilization of particulate organic matter from slough to ridge environments may play an important role in the maintenance of the Everglades freshwater landscape; and (3) Historical changes in hydrology have resulted in significant vegetation shifts from historical slough type vegetation to present ridge type vegetation.