Orientadores: Antonio Jose Gomez Cobo, Wagner Alves Carvalho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-13T07:06:47Z (GMT). No. of bitstreams: 1 Zanutelo_Cristiane_M.pdf: 6296648 bytes, checksum: d0a5733122c9f01d2f0c76ea9acfe714 (MD5) Previous issue date: 2009 / Resumo: A hidrogenação parcial do benzeno é uma reação química de interesse industrial, uma vez que o cicloexeno obtido pode ser empregado para a produção de diversos produtos. Além disso, ainda encontra uma importante aplicação na proteção ambiental, face às severas restrições à presença de compostos aromáticos nos combustíveis. O presente trabalho tem o objetivo de estudar a influência do tratamento aplicado ao suporte no desempenho de catalisadores de Ru sobre carvão ativado, destinados à reação de hidrogenação parcial do benzeno em fase líquida. Para tanto, um carvão ativado comercial foi submetido a diferentes tratamentos físicos e/ou químicos. Os sólidos obtidos foram empregados como suporte na preparação de catalisadores 5 % Ru/C. Os catalisadores foram preparados através de impregnação à seco, partindo-se de uma solução aquosa do precursor RuCl3.xH2O. Após impregnação, alguns catalisadores foram submetidos a uma redução direta sob H2, à temperatura de 423 K, com o intuito de avaliar os efeitos de tal tratamento de ativação. Os suportes preparados foram caracterizados através da adsorção de N2 (método de B.E.T.), titulação de Boehm, titulação potenciométrica e da determinação da entalpia de imersão em água. A espectroscopia de fotoelétrons excitados por raios X foi utilizada para estudar a superfície de suportes e catalisadores, enquanto que a microscopia eletrônica de varredura possibilitou determinar a composição química e observar a morfologia dos catalisadores. O desempenho dos catalisadores de Ru/C foi avaliado na reação de hidrogenação do benzeno em fase líquida, empregando-se um reator Parr do tipo "slurry". A reação foi conduzida sob pressão total de 5,0 MPa de H2, à temperatura de 373 K e com a presença de água no meio reacional. Os resultados obtidos indicam que o desempenho catalítico do sistema Ru/C é influenciado por determinados grupos funcionais presentes na superfície do carvão ativado. Os grupos carbonila diminuem a atividade e a seletividade da reação, enquanto que um aumento dos grupos carboxílicos conduz a catalisadores mais ativos e a maiores rendimentos em cicloexeno. / Abstract: The partial hydrogenation of benzene is a chemical reaction of industrial interest, as the cyclohexene obtained may be used to production of several products. Moreover, it also finds important application in the ambient protection, face to the severe restrictions to the aromatical composite presence in fuels. The aim of the present work is to study the influence of the treatment applicated the support on the performance of Ru catalysts on activated charcoal, to the benzene partial hydrogenation reaction in liquid phase. Therefore, commercial activated charcoal was submitted by means of different physical and/or chemical treatments. The solids obtained were used as support to the preparation of 5 wt.% Ru/C catalysts. The catalysts were prepared by incipient wetness impregnation method, through an aqueous solution of the precursor RuCl3.xH2O. After impregnation, some catalysts were submitted a direct reduction in H2 atmosphere at the temperature of 423 K, in order to evaluate the effects of such treatment of activation. The supports prepared were characterized by N2 adsorption (B.E.T. method), Boehm's titration, potenciometric titration and determination of the enthalpy of immersion in water techniques. The X-ray photoelectron spectroscopy technique was used to study the surface of supports and catalysts, whereas the electronic scanning microscopy allowed to determine the chemical composition and observe the morphology of the catalysts. The performance of the Ru/C catalysts was evaluated in the benzene hydrogenation reaction, using a Parr reactor of type "slurry". The reaction was conducted under total pressure of 5,0 MPa of H2 at a temperature of 373 K, with the presence of water in reactional medium. The results obtained indicate that the catalytic performance of the system Ru/C is influenced for determined functional groups present on the surface of activated charcoal. The carbonyl groups decrease the activity and selectivity of the reaction, while an increase of the carboxylic groups leads to more active catalysts and the highest yield of cyclohexene. / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

Orientador: Regina Maura Bueno Franco / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-08T19:15:28Z (GMT). No. of bitstreams: 1 Santos_LucianaUrbanodos_D.pdf: 2872201 bytes, checksum: 3d486b0bfc4357c133c090e92209db49 (MD5) Previous issue date: 2007 / Resumo: Entre muitas doenças de veiculação hídrica, a criptosporidiose e a giardiose são de particular interesse para a Saúde Pública, porque oocistos de Cryptosporidium spp e cistos de Giardia spp. podem persistir por longos períodos no ambiente, sendo que estes dois protozoários patogênicos têm sido implicados como a causa de muitos surtos epidêmicos de gastroenterites nos últimos 25 anos.Em muitos desses surtos, o esgoto doméstico foi incriminado como a fonte de contaminação do manancial; os variados métodos de tratamento de esgoto não removem totalmente agentes patogênicos, evidenciando a necessidade de desinfecçãodo esgoto tratado antes do seu lançamento no corpo hídrico. Uma forma de tratamento de esgoto amplamente utilizada é o processo por Iodos ativados, onde a degradação da matéria orgânica é realizada por bactérias aeróbicas.Em função da resistência de Cryptosporidium spp e Giardia spp. Ao processode desinfecção por cloração, a radiação por luz ultravioleta (UV) têm sidoavaliada como um processo alternativo. Para avaliar a eficiência de remoção de oocistose cistos pelo processo de Iodo ativado e de um reator de luz UV em inativaroocistos e cistos em uma Estação de Tratamento de Esgoto (ETE) da cidadede Campinas, 3 tipos de amostras foram selecionados para o estudo: I) afluente (n=53), iii) efluente desinfetado por luz UV (n=38) e, iii) efluente sem desinfecção por luz UV (n=53). As amostras de afluente foram concentradas por centrífugo-concentraçãoe as amostras de efluente (desinfetadas ou não por luz UV) foram processadas por filtração em membrana de éster de celulose) e, a visualizaçãodos protozoários, feita pela reação de imunofluorescência direta, com anticorposmonoclonais. A avaliação do processo de desinfecção por luz UV foi realizada com experimento de infectividade animal, inoculando-se 14/ cistos camundongos da linhagem BALB!c nude. Cistos de Giardia spp foram mais freqüentes e em maior densidade nos três tipos de amostras. Oocistos de Cryptosporidiumspp. foram observados somente em 2 amostras de afluente e em apenas uma amostra de efluente desinfetado por luz UV. O tratamento de esgoto pelo processo de Iodo ativado reduziu 98,9 % dos cistos e 99,7 % dos oocistos. A administração intragástrica de cistos de Giardia spp. desinfetados ou não por luz UV em camundongos, resultou na liberação de cistos de Giardia spp., nas fezes e trofozoítos foram observados nas lâminas confeccionadas por aposição do intestino. Estes resultados indicam que a desinfecção por luz UV não foi completamente eficiente na inativação dos cistos de Giardia spp, no caso da ETE estudada / Abstract: Among many water-borne diseases the cryptosporidiosis and giardiosis are of particular public health interest, because Cryptosporidium spp. oocysts and Giardia spp. cysts can persist for long periods in the environment, and both pathogenic protozoa have been implicated as the cause of many outbreaks of gastroenteritisin the last 25 years. In many of those outbreaks, the domestic sewer was incriminated as to source of contamination of the spring; they varied treatment sewage approaches do not remove entirely agent's pathogens, showing up the need of disinfection of the treated effluent before of their launching in the water body.A form of address of sewer broadly utilized is the trial by activated sludge whichway the degradation of the organic matter is carried out by aerobic bacteria and, in function of the resistance of Cryptosporidium spp and Giardia spp. to the chlorinedisinfection, the ultraviolet light (UV) has been evaluated like an alternative trial of disinfection. In order to evaluate the efficiency of cysts and oocysts removal by the activated sludge process, and by a UV reactor in inactivating cysts and oocystsin one Wastewater Treatment Plant (Wl/VTP)in Campinas, three sampling points were selected for study: i) influent (n=53),iii) treated effluent with UV disinfection (n=38) and iii) treated effluent without UV disinfection (n=53). The influent samples were concentrated by centrifugation and effluent samples (disinfectedwith UV light or not) were processed by cellulose esters membrane filtration, and protozoan visualization was analyzed by fluorescent monoclonal antibodytests. The investigation of disinfection potential by UV light was made with infectivityassay. Each mice of linage BALB/c nude were intragastrically inoculated a mean dosage 14 cysts. Giardia spp cysts prevailed with higher density in the three different sample types. Cryptosporidium spp. oocysts were observed in only 2 samples of influent and in just one sample of treated sewage with UV disinfection.The treatment by the activated sludge process promoted a reduction of 98.9% of cysts and 99.7 % of oocysts. Gastric intubation of Giardia spp. Cysts disinfected ar not by UV light to mice resulted in cysts released in feces and trophozoiteswere also observed toa in intestinal scrapings. The findings of this study indicate that disinfection by UV light was not completely efficient regarding the inactivationof Giardia spp cysts in the case of the / Doutorado / Doutor em Parasitologia

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / As emissÃes de gases poluentes devido à queima de combustÃveis fÃsseis sÃo as principais fontes emissoras de gases, tais como o CO2, que causam o efeito estufa. Neste Ãmbito, a remoÃÃo de CO2 por adsorÃÃo tem sido estudada como uma alternativa para atenuar os efeitos ao ambiente. Este estudo apresenta o projeto, montagem e validaÃÃo experimental de um sistema microcalorimÃtrico de adsorÃÃo para mediÃÃes simultÃneas de isotermas e calores de adsorÃÃo aplicados à caracterizaÃÃo de materiais adsorventes. A metodologia experimental dividiu-se em trÃs etapas: calibraÃÃo elÃtrica do microcalorÃmetro, montagem do sistema volumÃtrico de adsorÃÃo e mediÃÃes simultÃneas de equilÃbrio e curvas calorimÃtricas de adsorÃÃo de CO2 em adsorventes. O microcalorÃmetro foi calibrado eletricamente pelos mÃtodos do input elÃtrico e estado estacionÃrio. Contudo, somente o valor de constante de calibraÃÃo, K, obtido pelo input elÃtrico foi considerado nos cÃlculos de calores diferenciais de adsorÃÃo, uma vez que à mais representativo da resposta calorimÃtrica à adsorÃÃo de gases. O sistema volumÃtrico foi construÃdo em aÃo inoxidÃvel e, entÃo, calibrado para obter com precisÃo o nÃmero de moles adsorvidos em cada estÃgio de equilÃbrio. Finalmente, foram obtidas isotermas e calores diferenciais de adsorÃÃo de CO2 em adsorventes. As amostras foram previamente caracterizadas em relaÃÃo as suas propriedades texturais. O carbono ativado exibiu alta Ãrea superficial BET e alto volume microporos, que à caracterÃstico desta classe de materiais. O processo de funcionalizaÃÃo do zeÃlito 13X reduziu o valor de superfÃcie especÃfica em aproximadamente 16%, devido à obstruÃÃo parcial dos poros pela soluÃÃo de amina. Nos ensaios microcalorimÃtricos de adsorÃÃo, as curvas calorimÃtricas de CO2 a 273K para o zeÃlito 13X concordaram bem com os dados disponÃveis na literatura validando, pois, o sistema microcalorimÃtrico. A reprodutibilidade do sistema foi verificada atravÃs de experimentos de adsorÃÃo de CO2 a 273 K em carbono ativado. Para o zeÃlito 13X funcionalizado, a curva calorimÃtrica diferencial revelou que o processo de fisissorÃÃo à acompanhado pelo fenÃmeno de adsorÃÃo quÃmica devido à presenÃa da amina na superfÃcie do sÃlido. / Emissions of pollutant gases from the burning of fossil fuels are the main sources of gases such as CO2, which cause the greenhouse effect. In this context, the CO2 removal by adsorption has been studied as an alternative to reduce the effects to the environment. This study presents the design, assembly and experimental validation of a microcalorimetric adsorption system for simultaneous measurements of isotherms and heats of adsorption applied to the characterization of the adsorbent material. The experimental methodology was divided into three steps: the electric calibration of the microcalorimeter, the assembly of the volumetric adsorption system and the simultaneous measurements of the equilibrium and calorimetric curves of adsorption of CO2. The microcalorimeter was calibrated by the electrical input and the steady state methods. However, only the value of calibration constant, K, obtained by the electrical input was considered in the calculation of the differential heats of adsorption, because of it is more representative of the calorimetric response for the adsorption of gases. The volumetric system was constructed in stainless steel and then calibrated accurately to get the exact number of adsorbed moles at each equilibrium stage. Finally, it was obtained isotherms and differential heats of adsorption of CO2 on representative adsorbents. The samples were previously characterized for their textural properties. The activated carbon exhibited high BET surface area and micropore volume, which is characteristic of this type of material. The process of functionalization of the zeolite 13X has reduced the value of specific surface in approximately 16% due to the partial blockage of the pores by amine. In the microcalorimetric adsorption analysis, the calorimetric curves of CO2 at 273 K for the zeolite 13X agreed well with the available data in the literature, validating the microcalorimetric system. The reproducibility of the system was verified through experiments of adsorption of CO2 at 273 K on activated carbon sample. For the functionalized zeolite 13X, the differential calorimetric curve showed that the physisorption process is accompanied by the chemical adsorption phenomenon due to the presence of the amine on the surface of the solid.

Tendo em vista a existência de muitas comunidades no Estado de São Paulo (e em outros estados do Brasil), que utilizam água muitas vezes com qualidade imprópria ao consumo humano, o presente trabalho visa o desenvolvimento de uma instalação de filtração utilizando Carvão Ativado Impregnado com Prata (CAIP) com o intuito de eliminar alguma contaminação na água tratada devido à problemas tais como anomalias operacionais na ETA, tecnologia de tratamento inadequada, contaminação da rede de distribuição, reservação, dentre outros. Para a investigação experimental foram preparados três tipos de água de estudo, com baixos valores de turbidez e cor aparente. A água tipo I era isenta de contaminação, as águas tipo II e III apresentaram coliformes totais e fecais, sendo que a água tipo III utilizada na simulação da instalação como filtro domiciliar. Os ensaios realizados apresentaram taxa de filtração entre 200 e 250 m3/m2*d. Os resultados indicam que o CAIP apresentou propriedades adsorventes e é um poderoso agente desinfetante, reduzindo significativamente o NMP de coliformes totais e fecais de águas contaminadas. Porém, a desinfecção não foi completa e ocorreu excessivo desprendimento da prata do CAIP, inviabilizando o uso deste CAIP nesta instalação desenvolvida. / Minding the existence of many communities within the state of São Paulo (and other Brazilian states) which often use water unfit for human consumption, this work aims at the development of a filtering installation that uses Activated Carbon supporting Silver (AC(Ag)) in an attempt to eliminate any contamination in treated water. Such water contamination problems include, operational anomalies in the WTP, inadequate treatment technologies, contamination in the distribution net, and other filter specific problems. For the experimental investigation three types of test water were prepared, with low turbidity and apparent color values. Water type I was contarnination-free, water type II and III had total and fecal coliforms, and water type III was used in the simulation of domestic filtering installation. Tests showed a filtering rate between 200 and 250 m3/m2*d. Results point that AC(Ag) has adsorbent capabilities, in addition to being a powerful disinfection agent, and reduced significantly the number of total and fecal coliforms of contaminated waters. However, disinfection was not thoroughly, and silver was excessively dragged away, from the Activated Carbon, thus rendering the use of AC(Ag) unadvisable in the developed installation.

Orientador: Antonio José Gomez Cobo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-22T19:24:54Z (GMT). No. of bitstreams: 1 Zanutelo_Cristiane_D.pdf: 2910655 bytes, checksum: 8d8d65f2ea3f6afa0b73d7827013acc8 (MD5) Previous issue date: 2013 / Resumo: A hidrogenólise da sacarose é uma reação química de interesse industrial, uma vez que os produtos obtidos, sob a forma de glicóis e polióis, podem ser empregados em diversos setores produtivos, tais como indústrias farmacêuticas e de alimentos. Nesse contexto, o presente trabalho tem como objetivo estudar a preparação de catalisadores de Ni e Ru suportados em carvão ativado, destinados à hidrogenólise da sacarose em meio aquoso. Para tanto, catalisadores com uma fração mássica total de 5 % de metal foram preparados através dos métodos de impregnação incipiente e úmida, a partir de soluções aquosas de precursores clorados. Antes das impregnações, o suporte de carvão ativado comercial foi submetido a um tratamento químico com solução aquosa de KOH. Os sólidos preparados por meio da impregnação incipiente foram reduzidos a 473 K (200 ºC), sob fluxo de H2. Por sua vez, a impregnação úmida foi conduzida a 353 K (80 ºC), para diversos valores de pH, sendo a redução dos catalisadores realizada com formaldeído ou NaBH4. Os sólidos foram caracterizados através das técnicas de adsorção de N2 (método de B.E.T.), titulação de Boehm, titulação potenciométrica, espectroscopia de fotoelétrons excitados por raios X, microscopias eletrônicas de varredura e de transmissão, difratometria de raios X e redução à temperatura programada. Os desempenhos catalíticos na reação de hidrogenólise da sacarose foram conduzidos num reator Parr do tipo "slurry", à temperatura de 523 K (250 ºC) e sob pressão de H2 de 5,0 MPa (50 atm), utilizando-se uma massa de 5 g do catalisador. Os resultados revelam que os catalisadores de Ni/C preparados por impregnação úmida são mais ativos e seletivos a 1,2 propanodiol que os preparados via impregnação incipiente. A impregnação úmida também leva a catalisadores de Ru/C seletivos, que se mostram mais ativos que os preparados por impregnação incipiente. Contudo, a impregnação incipiente permite obter catalisadores igualmente seletivos, sendo que, em ambos os casos, o tratamento do suporte com KOH tem um efeito marcante no aumento do rendimento de 1,2 propanodiol / Abstract: The sucrose hydrogenolysis is a chemical reaction of industrial interest, since the obtained products, under the form of glycols and polyols, can be employed in different production sectors such as pharmaceutical and food industries. The present work aims to study the preparation of Ni and Ru catalysts supported on activated carbon, for the sucrose hydrogenolysis in aqueous media. For this purpose, catalysts with a total fraction of 5 wt % of metal were prepared by the methods of incipient and wet impregnation from aqueous solutions of chlorinated precursors. Before impregnation, the support of activated carbon was subjected to a chemical treatment in an aqueous solution of KOH. The solids prepared by incipient impregnation were reduced at 473 K (200 °C) under H2 flow. In its turn, the wet impregnation was conducted at 353 K (80 °C), for various pH values, being the catalysts reduction performed with formaldehyde or NaBH4. The solids were characterized by the techniques of N2 adsorption (B.E.T. method), Boehm titration, potentiometric titration, X ray photoelectron spectroscopy, scanning and transmission electronic microscopies, X ray diffraction and temperature programmed reduction. The catalytic performances for the sucrose hydrogenolysis were conducted in a Parr reactor of slurry type at temperature of 523 K (250 ° C) under H2 pressure of 5.0 MPa (50 atm), employing a catalyst mass of 5 g. The results reveal that the Ni/C catalysts prepared by wet impregnation are more active and selective for 1,2 propanediol than those prepared via incipient impregnation. The wet impregnation also leads to selective Ru/C catalysts, which are more active than those prepared by incipient impregnation. However, the incipient impregnation achieves also to selective catalysts, being that in both cases, the support treatment with KOH has a marked effect on increasing the yield of 1,2 propanediol / Doutorado / Sistemas de Processos Quimicos e Informatica / Doutora em Engenharia Quimica

Abstract Cardiac hypertrophy and remodelling are mechanisms of adaptation to increased workload and acute injuries of the heart. In the long-term, these initially beneficial mechanisms become detrimental and ultimately lead to the development of heart failure. The molecular determinant of myocardial remodelling and heart failure is altered intracellular signal transduction and a modified gene expression pattern in the individual cardiomyocyte. This study was aimed at characterising the changes in mitogen-activated protein kinases (MAPKs) and their nuclear effector, GATA-4, and their functional significance and interaction in experimental models of increased cardiac workload and remodelling. To study the effects of increased cardiac workload on MAPKs and GATA-4, isolated perfused rat hearts were subjected to increased left ventricular wall stress and their activities were determined using western blot and gel mobility shift assays. Left ventricular wall stress rapidly activated the DNA binding of GATA-4, and this activation was abolished in the presence of endothelin-1 (ET-1) and angiotensin II receptor antagonists. Furthermore, the activation of GATA-4 DNA binding was significantly attenuated by p38 MAPK and extracellular signal regulated kinase (ERK) inhibition. To gain further insights into the role of p38 MAPK as a regulator of cardiac transcription factors, gene expression and remodelling, a gene transfer protocol of increased p38 MAPK activity was established. Direct adenovirus-mediated gene transfer of wild-type p38α and constitutively active upstream kinase mitogen-activated kinase kinase 3b (MKK3b) selectively increased p38 MAPK activity in the left ventricle, which was followed by up-regulation of cardiac gene expression, myocardial inflammation and fibrosis. Using a DNA microarray approach, the cardiac target genes of p38 MAPK were identified, including several cell division, inflammation and signal transduction-associated genes. Furthermore, p38 MAPK over-expression was found to increase the DNA binding activities of several transcription factors, including GATA-4. Finally, the functional role of p38 MAPK was determined using adenovirus-mediated gene transfer in an experimental model of myocardial infarction. Post-infarction remodelling was characterised by a sustained down-regulation of p38 MAPK, while rescue of p38 MAPK activity attenuated post-infarction remodelling through anti-apoptotic and angiogenic mechanisms. These results indicate that p38 MAPK is a key regulator of GATA-4 transcription factor and cardiac gene expression during left ventricular wall stress and remodelling. They demonstrate that p38 MAPK, being cardioprotective in the infarcted heart but promoting inflammation and fibrosis in the normal heart, has a unique dual role in the myocardium.

Two batch mesocosms were created on site in Da Nang, Vietnam to reduce nutrients in wastewater from fish processing factories. The mesocosms contained either activated carbon or coconut fibre which in earlier studies has shown promising results in wastewater treatment. Three aspects of the materials were compared; Chemical content, which measured levels of COD, total-nitrogen and total-phosphorus. Rate of biofilm formation, where biofilm were measured visually and through weight. The last aspect was microbiological presence where fours species of microorganisms were cultivated. The experiment showed no obvious difference between the materials but concludes that this is an experiment that could and should be developed further.

Submitted in fulfillment for the Degree of Masters of Applied Sciences (Biotechnology), Durban University of Technology, Durban, South Africa, 2016. / Activated sludge (AS) flocs are paramount in biological treatment of wastewater, are comprised of microbial consortia with organic and inorganic material bound together by extra polymeric substances (EPS). The filamentous bacteria play a vital role in the floc formation process by providing the necessary structural support. Presence of epiphytic attachment on selected filamentous bacteria is a commonly occurring phenomenon in activated sludge samples. Different theories have been proposed to describe this phenomenon; however, not much research has been carried out to explore the profundity of the attachment. In this study, an attempt has been made to elucidate the intrinsic nature of the epiphytic attachment between the bacterial rods and filamentous bacteria based on microscopic (morphological and structural) analysis. Characterization of these epiphytes were performed using fluorescence in situ hybridization (FISH) at group level using Alpha, Beta and Gamma Proteo-bacterial probes. Morphological characteristics of filament hosts and the bacterial rods at the interface region was assessed using scanning electron microscopy (SEM). The SEM micrographs indicated that the attachment was facilitated by more than the EPS layer. Further ultrastructural examination using transmission electron microscopy (TEM) indicated a possible cell-to-cell interaction between epiphytes and the selected filaments. Fibrillar structures resembling amyloid-like proteins were observed within the filament cell targeted by the epiphytes. An interaction was apparent between the amyloid like proteins and the epiphytes as exhibited by the direction of fibrillar structures pointing towards the approaching epiphytes. Common bacterial appendages such as pili and fimbria were absent at the interface and further noted was the presence of cell membrane extensions on the epiphytic bacteria protruding towards the targeted filamentous cell. The sheath of host filaments however, remained intact and unpenetrated, during colonization. Amyloid-like fibrils at interface may potentially play the role of attachment sites for the attaching epiphytes, as attachment facilitating appendages were not visualized. / M

M.Ing. / The Rietvlei Water Treatment Plant was extended with a granular activated carbon (GAC) filtration system after an exhaustive series of tests, which were started in 1994. Upon commissioning towards the middle of 1999, a year of close monitoring followed to measure the GAC performance at full-scale. After verification that the GAC does indeed ensure a high quality product under all conditions, the emphasis shifted to the optimisation of the GAC handling and regeneration system. Frequently moving the entire GAC inventory from the filters to an off-site regeneration plant and back requires significant operational effort and contributes a major part of the total cost of the GAC system. A number of systematic investigations were carried out in response to a number of practical questions that arose at Rietvlei. The first part of the study was directed towards tracking and quantifying the GAC on and off site. The main findings were that 10.0% of the GAC is lost from the filter during backwashing (0.3%) and removal of GAC from the filter for regeneration (9.7%). The sump traps not all this GAC and 2.3% of the total inventory is lost to the river. Inserting a sieve at the outlet of the sump can eliminate this loss. A further 80.3% of the GAC in a filter is removed for regeneration, of which 18.7% is lost during the regeneration process. The minimising off this loss can only be achieved through the optimisation of the regeneration process, which falls within the domain of the regeneration contractor. The second part of the study was directed at the behaviour of the GAC whilst within the filter bed. The porosity and sphericity was determined by laboratory tests and calculations. The porosity was found to be 0.69 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon and the sphericity was found to be 0.67 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon. By using a calibrated bed expansion model, the bed expansion could be calculated at 9°C and 23°C for the two carbons gradings; the maximum temperature range experienced at Rietvlei. The main finding of this part of the study was that the average available freeboard is 650 mm for the 12 x 40 grading and 430 mm for the 8 x 30 grading, and therefore no GAC should wash over the weir at all during backwashing. The third part of the study measured the physical changes of the GAC found at different points in the GAC cycle. The main findings were that the small fraction of GAC washed out of the bed during backwashing and removal has a finer grading, higher apparent density and lower adsorption capacity than the GAC in the filter bed. There seems to be no marked attrition of the carbon or generation of fines during the removal and transport of the GAC to the regeneration plant. After regeneration, there was a 7% decrease in apparent density and a 30% increase in adsorption capacity. The final part of the study correlated the adsorption capacity of the GAC with its time in use as well as UV254 removal. After regeneration, UV254 removal begins at approximately 20% and declines to 14% after 400 days of operation, and to 10% after 600 days. After regeneration, the iodine number begins at approximately 800, declines to 600 after 400 days of operation, and to 500 after 600 days.

The potential for using readily available and cost-effective complex carbon sources such as primary sewage sludge for a range of environmental remediation processes, including biological sulphate reduction, biological nutrient removal and the bioremediation of acid mine drainage, has been constrained by the slow rate of solubilization and low yield of soluble products, which drive the above mentioned processes. Previous work conducted by the Environmental Biotechnology Group at Rhodes University indicated that the degradation of primary sewage sludge was enhanced under sulphate reducing conditions. This was proven in both laboratory and pilot-scale (Reciprocating Sludge Bed Reactor) systems, where the particulate matter accumulated in the sludge bed and the molecules in smaller flocs were rapidly solubilized. The current study was aimed at investigating in more detail the factors that govern the enhanced hydrolysis under sulphate reducing conditions, and to develop a descriptive model to explain the underlying mechanism involved. The solubilization of primary sewage sludge under sulphate reducing conditions was conducted in controlled flask studies and previously reported findings of enhanced hydrolysis were confirmed. The maximum percentage solubilization obtained in this study was 31% and 63% for the methanogenic and sulphidogenic systems respectively, and this was achieved over a period of 10 days. A rate of reducing sugar production and complex molecule breakdown of 51 mg. L⁻¹.hr⁻¹ and 167 mg.L⁻¹.hr⁻¹ was observed for the methanogenic and sulphidogenic systems respectively. The flask studies revealed that during hydrolysis of primary sewage sludge under sulphidogenic conditions there was enhanced production of soluble products, specifically carbohydrates (reducing sugars) and volatile fatty acids, compared to methanogenic conditions. The rate at which these products were utilized was also found to be more rapid under sulphidogenic as compared to methanogenic conditions. A study of the distribution of volatile fatty acids indicated that acetate was utilized preferentially in the methanogenic system, and that propionate, butyrate and valerate accumulated with time. The converse was found to occur in the sulphidogenic system. The descriptive model developed from the results of this study was based on the fact that a consortium of bacteria, composed of hydrolytic, acidogenic and acetogenic species, carries out the solubilization of complex carbon sources. Furthermore, it is essential that equilibrium between product formation and utilization is maintained, and that accumulation of soluble end products impacts negatively on the rate of the hydrolysis step. It is therefore proposed that the relatively poor utilization of VFA and reducing sugars in the methanogenic system activates a negative feedback inhibition on the hydrolytic and/ or acidogenic step. This inhibition is reduced in the sulphidogenic system where the utilization of end products is higher.