Water treatment residues (WTRs), which are by-products from the production of potable water, are chemically benign, inorganic materials which are suitable for disposal by land application. Their high phosphorus (P) sorption capacities have, however, generated some concern in an agronomic context where P is recognised as a growth limiting plant nutrient. The extent to which labile P pools are reduced or enhanced by WTR amendments is, therefore, a central issue with respect to their disposal by land application. Therefore, the aim of this study was, through the use of empirical adsorption isotherm equations and chemical fractionation of P within the residues, to investigate the chemical processes responsible for the retention and release of P from 15 South African WTRs. Chemical characterisation revealed considerable variation in residue properties relevant to P sorption-desorption processes. pH, exchangeable Ca and organic carbon content ranged from 4.77 to 8.37, 238 to 8 980 mg kg-1 and 0.50 to 11.6 %, respectively. Dithionate, oxalate and pyrophosphate extractable Al fractions ranged from 741 to 96 375, 1 980 to 82 947 and 130 to 37 200 mg kg-1, respectively. Dithionate, oxalate and pyrophosphate extractable Fe ranged from 441 to 15 288, 3 865 to 140 569 and 230 to 90 000 mg kg-1 respectively. Therefore mechanisms of retention were hypothesised to be residue specific, being dependent on the unique chemical properties of the sorbent. Elevated Ca and amorphous Al and Fe concentrations did, nevertheless, suggest that all residues had the capacity to adsorb high amounts of P and to retain this P in forms unavailable for plant uptake. These arguments were confirmed by the sorption study where labile P was, for all residues, found to constitute a small fraction of total applied P even at high application concentrations (128 mg P L-1). Sequential P fractionation revealed that most of the inherent P (which ranged from 1 149 to 1 727 mg P kg-1) and applied P were retained in highly resistant mineral phases or fixed within the organic component. Thus P replenishment capacities were restricted even though residual P concentrations were often within adequate ranges for plant growth. Phosphorus adsorption data was described by four empirical adsorption isotherm equations in an effort to determine possible mechanisms of retention. Sorption data was, for most of the WTRs, described by the Temkin isotherm while the Freundlich and linear models fitted data for two residues each. A key finding was that the distribution coefficient (Kd) tended to increase with the quantity of P adsorbed (S) as opposed to decrease or remain constant in accordance with model assumptions. Therefore, the models could not be used for mechanistic interpretation, even though they provided excellent descriptions of the data. The direct relationship between Kd and S suggested a mechanism of retention involving the activation of sorption sites. This notion was supported by the fractionation study which showed that P addition results in the transfer of an increasing quantity of organically bound P to resistant residual forms. Model affinity parameters were strongly correlated to dithionate and pyrophosphate extractable Al and Fe which suggested that P was adsorbed primarily through ligand exchange mechanisms. The mobility of P bound to organic fractions did indicate that P was retained through weaker forces of attraction such as monodentate ligand exchange, charge neutralisation or proton transfer. Evidence to support the notion that P is immobilised through the formation of Ca phosphates was lacking. Based on P fractionation data, it was suggested that strong chemisorption mechanisms and the diffusion of P into WTR micropores were largely responsible for the minimal quantity of P desorbed by disequilibria desorption processes. A greater quantity of P was desorbed in the presence of oxalate and citrate which suggested that plants may increase bio-available pools through the release of organic ligands. Phosphorus desorbed in the presence of these ligands did, however, decline with P addition which confirmed that the affinity of the WTR surface for P increases with P application. Therefore, it was concluded that the application of P to WTRs is an uneconomical process unless sorption sites are already saturated or immobilisation processes are inhibited. In light of these findings, it was suggested that the absence of plant P deficiencies under the field application of WTRs is due primarily to inhibited sorption. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

O objetivo deste trabalho foi o de otimizar a adição de estrôncio em liga A356 visando obter as melhores propriedades mecânicas de ductilidade. Foram estudados diferentes níveis de adição de estrôncio em ligas A356 com dois níveis de fósforo residual. Além disto, foi estudado o efeito de adições crescentes de magnésio na morfologia do silício em liga Al-7%Si modificada. Para a realização deste estudo, foram produzidos corpos de prova de tração segundo ASTM B108 com velocidade de resfriamento de 8°C/s. Os corpos de prova foram endurecidos por precipitação via tratamento térmico e tracionados. Além de uma avaliação quantitativa das propriedades mecânicas, amostras de todas as condições passaram por uma avaliação metalográfica qualitativa. Foi feito também ataque profundo para observação das morfologias das partículas de silício em microscópio eletrônico. O efeito da adição crescente de estrôncio na liga A356 em um intervalo de 0 a 256 ppm de estrôncio foi o de aumento do alongamento até teores de 50 a 60 ppm, seguido de uma diminuição do mesmo até 256 ppm. O teste de adição crescente de estrôncio foi repetido para uma liga A356 com teor residual de fósforo de aproximadamente 10 ppm. A curva de alongamento segue o mesmo formato da curva levantada para amostras que não continham fósforo, embora tenha sido encontrada uma sensível queda nos valores de alongamento na presença de fósforo. A presença de magnésio em ligas Al-Si modificadas por estrôncio foi responsável por uma mudança na morfologia de crescimento das partículas de silício nas regiões de contornos de células eutéticas, além do aparecimento de partículas intermetálicas nesta mesma região. Deste trabalho, concluiu-se que as melhores propriedades mecânicas de ductilidade foram obtidas para a adição de estrôncio de 50 a 60 ppm. / This work has, as its main objective, the optimization of the strontium addition in A356 alloy, in order to obtain the best ductility results. The addition of several different strontium amounts in alloys containing two phosphorous amounts was studied. Besides, the effect of increasing magnesium content on the morphology of the silicon particles of Al-7%Si modified alloy was also studied. Test bars were produced from ASTM B108 cooled at a rate of 8°C/s. The samples were heat treated and then tested. The mechanical properties were evaluated and the microstructures were analyzed. The silicon morphology was observed in deep etched samples at SEM. Strontium additions of 0 to 256 ppm increased the elongation up to 50-60 ppm. Above 75 ppm, the addition of strontium caused the elongation to decrease up to 256 ppm. The same test was reproduced for an alloy containing approximately 10 ppm P and, although the best results were achieved at strontium additions of 50-60 ppm, the elongation results were clearly lower. The presence of magnesium in Al-7%Si modified alloys was responsible for a change in the growth morphology of the silicon particles, especially near grain boundaries, and also for the formation of intermetallic particles in those areas. From this work, it was possible to conclude that the best ductility properties are achieved for strontium additions of 50-60 ppm.

The LD-process, called after the cities Linz and Donawitz, is used to convert pig iron into crude steel by blowing oxygen on top of the pig iron. A LD-LBE converter, Lance Bubbling Equilibrium, also stirs the melt trough a bottom stirring system. The bottom stirring in a LD-LBE converter is believed to have a positive effect alone on the phosphorous removal. Previous studies have shown that the temperature and slag composition are the main factors affecting phosphorus removal. Phosphorus binds to the slag easier at low temperature and to slag with certain levels of dissolved calcium (a process additive). Different praxes were tested and a better dephosphorisation was reached. The bottom stirrings effect on the dissolution of calcium additives is a possible explanation to the results and mechanisms presented in this study. The study also aimed to investigate the use of nitrogen as stirring gas instead of argon. Nitrogen is removed from the steel during the formation of carbon oxide gases. Nitrogen was used in varying amounts as stirring gas during the first half of the oxygen blow. It proved to be safe to use as long as there was a high content of carbon in the melt. However using nitrogen beyond half of the blow showed to be risky for nitrogen sensible steels; even in small amounts since there is not enough carbon left to degas the steel from nitrogen. Slopping happens when formed gas from the LD-process is trapped in the slag. The slag level rises and sometimes it floods the converter resulting in yield losses. The influence of the bottom stirring on slopping was studied, which resulted in the conclusion that slopping cannot be avoided by simply improving the bottom stirring. Although some verification studies remains to be done, if the suggestions based on the results of this thesis were employed, savings in the oxygen and stirring gas economies could be made. Not least improvements on the iron yield. / En järnmalmsbaserad stålproduktion börjar med att järnmalm matas i en masugn tillsammans med koks, kalk och tillsatsämnen. Ut kommer råjärn med höga kol och svavelhalter. Råjärnet transporteras till stålverket i så kallade torpedvagnar. I vissa stålverk, t.ex. SSAB Special Steels i Oxelösund, renas råjärnet från svavel i torpedvagnen. I andra stålverk svavelrenar man i separata skänkar. Svavelreningen sker med bland annat kalciumkarbid som binder till svavlet. Det svavelfattiga råjärnet måste sedan renas från kol för att bli stål. Det görs i en LD-konvertern (Linz Donawitz). LD-konvertern laddas med flytande råjärn som har en kolhalt på 4,5 procent och som är runt 1350 grader varmt. Råjärnet kyls genom att cirka 20 procent skrot tillsätts. En syrgaslans sänks sedan in i konvertern ovanför smältan och reningen startar.  Syrgaslansen blåser syrgas i ultraljudsfart vilket oxiderar en del av järnet, så väl som kol, kisel, mangan, fosfor and andra föroreningsämnen i råjärnet. Kol försvinner ur konvertern i form av kolmonoxidgas. Andra oxiderade föroreningar och järnoxid bildar tillsammans en så kallad slagg som flyter ovanpå smältan. Det tillsätts även så kallade slaggbildare som förbättrar upptaget av föroreningar i slaggen. Processen varar i cirka 17 minuter och är mycket beroende av slaggen som bildas. Kol försvinner ur konvertern i form av kolmonoxidgas. Under processens gång rör man om smältan med hjälp av gaser som spolas genom botten av konvertern. Omröringen jämnar ut smältans sammansättning och temperatur. När man inte länge behöver avlägsna kol stoppas processen. Stålets temperatur är då cirka 1700 grader och kolhalten ligger nära 0,05 procent. Stålet överförs sedan till en skänk för att skilja det ur slaggen. Stålet förädlas vidare i olika processer där sammansättningen justeras så att det möter kundens krav. Sedan gjuts stålet i strängar för transport till valsverk eller kunder. Denna studie behandlar bottenomrörningen under LD-processen i SSAB Special Steels's stålverk i Oxelösund. Omrörningen sker genom åtta porösa stenar i botten av konvertern som blåser med argon eller kväve. Gasflödet genom stenarna justeras genom ett ventilsystem. Under blåsningen rör man om med hjälp av förinställda program. Omrörningens primära funktion är att avlasta syrgaslansen. I fallen där ingen bottenomrörning finns måste syrgaslansen blåsa ”hårdare” på stålet för att avlägsna kol. Avlastningen som bottenomrörningen bidrar med gör att processen även kallas för LD-LBE, där LBE står för Lans Bubbling Equilibrium. Bottenomrörningen tros ha en positiv effekt på stålets rening från fosfor. Sedan tidigare vet man att temperatur och slaggsammansättning är de största faktorerna som påverkar fosforreningen. Fosfor tas lättare upp i slaggen vid låga temperaturen samt i slagg med högre kalkhalter. Olika omrörningsprogram testades och en bättre fosforrening nåddes. Bottenomrörningen visade sig ha positiva effekter som är teoretisk kopplade till kalksmältning. Två möjliga förklaringsmekanismer hittades. Studien undersökte även användningen av kväve som omrörningsgas istället för argon, då kväve är ekonomisk fördelaktig gentemot argon. Kväve finns inlöst i råjärnet som sätts in i konvertern. Kvävgasen försvinner ur stålet under och med hjälp av kolreningen. Det visade sig vara säkert att använda kväve från start fram till halva syrgasblåset på kvävekänsliga stålsorter, var efter man sedan byte till argon. Kväve som används sent under blåset visade ge högre kvävehalter. Urkok är en kraftig volymökning av slaggen som sker när bildad gas från reningen av smältan fångas i slaggen och får slaggen att ”koka över”. Urkok resulterar i ekonomiska förluster då slaggen som lämnar konvertern vid urkok är rik på järn. Bottenomrörningens eventuella påverkan på urkok studerades. Det visade sig att urkok inte kan undvikas genom att enbart optimera bottenomrörningen.

Membrane filtration is growing in popularity as a viable technology for drinking water treatment to meet high demand and regulatory requirements. While many improvements have been made to the technology in the past decade, fouling continues to be one of the major operational challenges associated with membranes as it increases operating costs and reduces membrane life. Fouling control typically requires some form of pre-treatment. Biofiltration is a ???green??? technique that can minimize chemical usage and waste during water treatment and is a relatively new application as a pre-treatment for membranes. Proteins and polysaccharides (biopolymers) have been found to contribute most to fouling of low pressure polymeric membranes. Biofiltration has recently been demonstrated as an effective pre-treatment method for reducing biopolymer-associated fouling of this type of membrane (Hall?? et al., 2009). Given that the concentration and composition of organic matter in water is variable, there is an opportunity to explore the applicability of this robust technology for different water types. The primary goals of this research were to assess the effectiveness of direct biofiltration in minimizing ultrafiltration polymeric (PVDF) membrane fouling and at the same time evaluate the biofilter development, biofilter performance based on organics removal potential, and the effect of phosphorus addition (as a nutrient) to the biofilter influent. A pilot-scale treatment train was constructed at the Technology Demonstration Facility at the Walkerton Clean Water Centre. It included two parallel dual media (sand/anthracite) biological filters (preceded by roughing filters), followed by an ultrafiltration membrane unit. Experiments were conducted using water from the Saugeen River (Ontario, Canada) whose primary form of carbon is humic material. The biofilters were allowed to acclimate and biofilter performance and organics removal were tested over a fourteen month period, the last four months of which were dedicated to phosphorus enhancement experiments. The membrane fouling experiments started seven months following the start-up of the biofilters, after confirmation of steady-state operation. Biofilter water samples were analyzed for natural organic matter constituents along with other water quality parameters, and biomass quantity and activity in the media were measured. Biomass activity in the biofilter media and biopolymer removal through the biofilter indicated a rapid acclimation period, and also demonstrated similar performance of the parallel biofilters during start-up and steady-state operation. The biofilters achieved 21% removal of the biopolymers on average following acclimation, while reduction of the humic fractions was not observed. A linear relationship between biopolymer removal and its concentration in the river water was observed (first-order process). Membrane fouling experiments were conducted using both untreated and biofiltered river water. The fouling rates were computed by monitoring changes in transmembrane pressure over time. Analysis of the samples with liquid chromatography-organic carbon detection confirmed the significant contribution of biopolymers to irreversible and reversible membrane fouling rates even when only present at low concentrations. During the phosphorus enhancement phase, two different phosphorus doses were fed into the influent of one of the parallel biofilters in order to achieve a target C:N:P ratio of roughly 100:10:1. Although initially (first month of the dosing period) an increase in the removal of dissolved organic carbon and ultraviolet-absorbance was observed in the phosphorus-enhanced biofilter, this was not sustained. Phosphorus addition did not affect biopolymer removal or biomass quantity and activity in the biofilter, and the membrane fouling experiments during this period did not show any significant effect of phosphorus addition.

Abstract Purification techniques for leachate from composting activity - analysis in terms of ammonia nitrogen, total phosphorus and BOD Sofia Lundkvist Leachate from compost facilities has a large impact on the environment if is not properly cleaned. Water samples taken at Ragn-Sells compost facility at Dåva in Umeå have had problems with high amounts of BOD (biochemical oxygen demand), ammonia nitrogen and total phosphorus in their leachate and need to lower these. The aim of this work was to investigate the methods available for treatment of these substances, see if there is a variation depending on spring and autumn in the presence of substances in the leachate from Dåva, and to investigate whether there are methods that can complement Ragn-Sells existing facility for the purification of leachate. Water samples were used to test season-differences of BOD, ammonia nitrogen and total phosphorus. Furthermore, I did interviews with persons from other compost facilities around Sweden to identify alternative methods to reduce the amount of those three substances in leachate from Dåva. There were no clear pattern between measurements in spring and autumn, but the analysis from Dåva shows that there is a statistically significant negative correlation between ammonia nitrogen with average temperature. When the temperature drops the concentration of ammonia nitrogen increases. Further analysis shows that Dåvas existing system likely can be supplemented with additional steps to improve purification of BOD, ammonia nitrogen and total phosphorus, but the data I received was not enough to declare witch method works best for Ragn-Sells as the majority of the persons I came in contact with could not account for the measured values of the three substances.

O objetivo deste trabalho foi o de otimizar a adição de estrôncio em liga A356 visando obter as melhores propriedades mecânicas de ductilidade. Foram estudados diferentes níveis de adição de estrôncio em ligas A356 com dois níveis de fósforo residual. Além disto, foi estudado o efeito de adições crescentes de magnésio na morfologia do silício em liga Al-7%Si modificada. Para a realização deste estudo, foram produzidos corpos de prova de tração segundo ASTM B108 com velocidade de resfriamento de 8°C/s. Os corpos de prova foram endurecidos por precipitação via tratamento térmico e tracionados. Além de uma avaliação quantitativa das propriedades mecânicas, amostras de todas as condições passaram por uma avaliação metalográfica qualitativa. Foi feito também ataque profundo para observação das morfologias das partículas de silício em microscópio eletrônico. O efeito da adição crescente de estrôncio na liga A356 em um intervalo de 0 a 256 ppm de estrôncio foi o de aumento do alongamento até teores de 50 a 60 ppm, seguido de uma diminuição do mesmo até 256 ppm. O teste de adição crescente de estrôncio foi repetido para uma liga A356 com teor residual de fósforo de aproximadamente 10 ppm. A curva de alongamento segue o mesmo formato da curva levantada para amostras que não continham fósforo, embora tenha sido encontrada uma sensível queda nos valores de alongamento na presença de fósforo. A presença de magnésio em ligas Al-Si modificadas por estrôncio foi responsável por uma mudança na morfologia de crescimento das partículas de silício nas regiões de contornos de células eutéticas, além do aparecimento de partículas intermetálicas nesta mesma região. Deste trabalho, concluiu-se que as melhores propriedades mecânicas de ductilidade foram obtidas para a adição de estrôncio de 50 a 60 ppm. / This work has, as its main objective, the optimization of the strontium addition in A356 alloy, in order to obtain the best ductility results. The addition of several different strontium amounts in alloys containing two phosphorous amounts was studied. Besides, the effect of increasing magnesium content on the morphology of the silicon particles of Al-7%Si modified alloy was also studied. Test bars were produced from ASTM B108 cooled at a rate of 8°C/s. The samples were heat treated and then tested. The mechanical properties were evaluated and the microstructures were analyzed. The silicon morphology was observed in deep etched samples at SEM. Strontium additions of 0 to 256 ppm increased the elongation up to 50-60 ppm. Above 75 ppm, the addition of strontium caused the elongation to decrease up to 256 ppm. The same test was reproduced for an alloy containing approximately 10 ppm P and, although the best results were achieved at strontium additions of 50-60 ppm, the elongation results were clearly lower. The presence of magnesium in Al-7%Si modified alloys was responsible for a change in the growth morphology of the silicon particles, especially near grain boundaries, and also for the formation of intermetallic particles in those areas. From this work, it was possible to conclude that the best ductility properties are achieved for strontium additions of 50-60 ppm.

Four nickel-molybdenum catalysts were synthesized on gamma alumina with higher surface area and on NiMo catalyst was prepared using gamma alumina with lower surface area. Catalysts with higher-surface-area support were prepared by co-impregnation, sequential impregnation and adding phosphorous. Theses catalysts were calcined at 500  ͦC. Effect of higher calcination temperature was investigated by preparation of one catalyst calcined at 700 ͦC. Catalysts were thoroughly characterized via four characterization techniques. The hydrotreating activity of three catalysts was carried out in a micro reactor at high pressure and three different temperatures with Nynas vacuum middle distillate. Prior to the test, sulfiding was carried out to activate the catalysts. Hydrotreated-oil samples as products were analyzed to evaluate the activity and conversion of the catalyst. Also, the spent catalysts were characterized to evaluate the surface area characteristics and deactivation of catalysts. Addition of phosphorous to NiMo/gamma-Al2O3 improved the interaction between the metals and the support as well as reduced the coke formation as observed in scanning electron microscopy micrographs.

An unexpected biological removal of phosphorous in IVL Hammarby Sjöstadsverket pilot membrane bioreactor (MBR) wastewater treatment process was investigated by three distinct methods. a) Investigation and quantification of the biological phosphorous uptake (bio-P) capacity by phosphate release tests (PRT), b) validation of bio-P occurrence by granular polyphosphate (poly-P) staining and microscopy and c) metagenomic community structure analysis to map the sludge habitat. Validation of phosphate accumulating organisms (PAO) was successfully performed using the Neisser Methylene Blue Metachromatic staining protocol. Quantification by a novel staining protocol gave indications of the relative activity of bio-P in the bioreactor process line. The bio-P activity by PRT showed high capacity of phosphate accumulation in the treatment process. Furthermore, the use of ethylenediaminetetraacetic acid (EDTA) to induce stressful conditions was successfully shown to increase the release rate and depletion of intracellular poly-P of PAO. Finally, the impact of temperature dependency in PRT was investigated.A metagenomic community structure analysis by 16S rRNA successfully prepared 28 samples for sequencing and analysis. The project has successfully validated and quantified bio-P with an improved methodology as a foundation for upcoming studies of the treatment process. / En oväntad biologisk fosforrening (bio-P) i IVL Hammarby Sjöstadsverkets membranreaktorpilot undersöktes med tre distinkta metoder. Kvantifiering av det biologiska fosforupptaget undersöktes med fosforsläppstest (PRT). Validering av förekomsten av fosfatackumulerande organismer (PAO) via infärgning av polyfosfatgranuler med Neissers protokoll för infärgning med metylenblå. Ett nytt protokoll för kvantifiering av polyfosfatgranulkluster gav indikationer på relativ aktivitet av bio-P i reningsprocessens bioreaktorer. Bio-P aktiviteten som uppmättes med PRT visade på hög kapacitet av biologisk fosforackumulation. Vidare visades framgångsrikt att stresspåslag av PAO med etylendiamintetraättiksyra (EDTA) ökade fosfatsläppshastigheten och uttömningen av intracellulär poly-P. Slutligen undersöktes temperaturberoendet i PRT. En 16S rRNA metagenomikstudie gav 28 st prover redo att sekvensieras och analyseras. Projektet har framgångsrikt validerat och kvantifierat bio-P med en utvecklad metodologi som kan utgöra grunden för kommande studier vid reningsverket.

No description available.

Soybeans are economically and agriculturally the most important legume in the world, providing protein and oil to the food and animal feed industries and base ingredients for hundreds of chemical products. Their value could be enhanced, however, if the oil and protein content remained high and the oligosaccharide and phytate contents were lowered to make soybeans more acceptable for human and animal consumption. A soybean population of 55 families segregating for genes controlling quality traits was chosen for this study. Both parental lines have high sucrose and low stachyose. The former contains a high level of phytate while the latter is low phytate. The objective of this experiment was to determine whether or not both parents had the same gene(s) for low stachyose. An additional objective was to determine quantitative trait loci (QTL) controlling quality traits: sucrose, stachyose and phytate. An acetonitrile precipitation method and a modified colorimetric method were used to determine amounts of sugars and phytate, respectively. The phenotypic data for stachyose was analyzed and it was determined that two recessive genes control low stachyose content in this population. A map was constructed using 141 SSR markers and 15 molecular linkage groups (MLGs) were identified. After analyzing trait and marker data in QTL Cartographer, potential QTL were found on MLGs: B1, C2, D1b, F, M and N. Sucrose and stachyose QTL were identified on B1, C2, M and N. Phytate QTL were observed on B1, D1b, F and N. The markers identified for quality traits in this population may be useful in marker-assisted selection and the germplasm should be useful for the development of a cultivar. / Master of Science