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Ermel, Gwennola. "Etudes de bacteriophages virulents de streptocoques lactiques mesophiles." Rennes 1, 1989. http://www.theses.fr/1989REN10121.
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Etude des bacteriophages lytiques des bacteries lactiques. Les analyses morphologiques, de composition proteique et l'homologie adn-adn ont montre que les phages lytiques se repartissent en deux groupes, prolates et isometriques et qu'ils appartiennent a la famille des siphoviridae. L'analyse en microscopie electronique des genomes phagiques a permis d'emettre l'hypothese d'extremites cohesives. L'existence et la nature de celles-ci ont ete mise en evidence par le sequencage d'une partie du genome
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Jaffer, Ashraf. "An investigation into the mechanism of bioleaching of a predominantly-chalcopyrite concentrate with mesophiles." Master's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/5313.
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Includes bibliographical references.Bioleaching is an established technology for the treatment of refractory gold ores and concentrates. The bioleaching of sulphide minerals is a complex process in which bacterial and chemical oxidation processes occur simultaneously. Recent studies has provided convincing evidence that the bioleaching of pyrite occurs via a two-step mechanism (Boon, 1996).
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Creuly, Catherine. "Selection d'une collection industrielle de streptocoques mesophiles et thermophiles en vue de leurs utilisations en rotation dans les ferments lactiques." Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF2D206.
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Cette etude a contribue a creer une collection de streptocoques lactiques: st. Lactis subsp. Cremoris, st. Lactis subsp. Lactis, st. Lactis subsp. Diacetylactis (bacteries mesophiles) et st. Thermophilus. Onze souches de st. Cremoris appartenant a la collection existante ont ete selectionnees parmi 67 bacteries mesophiles apres des tests de lysotypie (sur 59 phages) et de lysogenie (par action de la mitomycine). Les memes tests ont ete realises sur 30 st. Thermophilus et 19 serums phagiques. Mais ces souches semblent posseder des systemes de restriction-modification puissants et sont donc moins sensibles aux phages. Le peu de phages recoltes n'ont pas permis d'etablir des groupes de lysotypie significatifs et les souches testees ne sont pas lysogenes. Afin d'ameliorer la collection, 554 bacteries mesophiles ont ete isolees; identifiees et leur pouvoir acidifiant determine
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MANSOUR, ET-TANI AHMED. "Role des proteases de paroi des bacteries lactiques mesophiles sur la texture et le gout des fromages a pate pressee." Clermont-Ferrand 2, 1989. http://www.theses.fr/1989CLF21192.
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Etude de differents clones (protease+ et protease) isoles de souches de l. Lactis. Ssp. Cremoris ou l. Lactis ssp lactis. Effets de ces clones sur les proprietes sensorielles du fromage. Etude de l'evolution de la composition chimique, jusqu'a l'affinage (acidite, matiere seche, caseine, par exemple). La maitrise de la proportion de variant proteane+ et protease permettent d'envisager de limiter les defauts de fabrication
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Alves, Matheus Bocchini Rodrigues. "Viabilidade de Campylobacter jejuni e microrganismos indicadores em ração de frangos de corte." Universidade Federal de Uberlândia, 2013. https://repositorio.ufu.br/handle/123456789/13100.
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The objective of this study was to evaluate the viability of Campylobacter jejuni and quantify indicator microorganisms (mesophilic bacteria, total coliforms and E. coli) in initial and final broiler feed artificially contaminated with 103 and 105 CFU of C. jejuni per gram of ration, kept at two different temperatures of storage (25 and 370C) and analyzed on four different storage periods 0, 24, 72 and 120 hours. C. jejuni survived throughout the study period and multiplied when inoculated with 103UFC, with the highest counts observed when the feed was kept at a temperature of 370C. Overall, there was a multiplication of mesophilic microorganisms, but the amount of coliforms didn´t increase with time. This work shows that the importance of feed in the epidemiology of C. jejuni in broilers should be better assessed and instigates other studies to verify the possible symbiotic relationship between C. jejuni and mesophilic.O objetivo desse estudo foi avaliar a viabilidade de Campylobacter jejuni e quantificar microrganismos indicadores (bactérias mesófilas, coliformes totais e E. coli) em rações inicial e final de frangos de corte artificialmente contaminadas com 103 e 105 UFC de C. jejuni por grama de ração, mantidas em duas diferentes temperaturas de armazenamento (25 e 370C) e analisadas em quatro períodos de armazenamento distintos 0, 24, 72 e 120 horas. A C. jejuni sobreviveu durante todo o período avaliado e se multiplicou quando inoculada 103 UFC, sendo observadas as maiores contagens quando a ração foi mantida na temperatura de 370C. Houve multiplicação de microrganismos mesófilos, mas a quantidade de coliformes não aumentou com o tempo. Este trabalho alerta para a necessidade de melhores investigações sobre a importância da ração na epidemiologia da C. jejuni em frangos de corte e a relação mesófilo e Campylobacter.
Mestre em Ciências Veterinárias
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Menezes, Tila de Alcantara. "Avaliação da temperatura de armazenamento e uso de antimicrobianos na qualidade de doses seminais de suínos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/179696.
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A bacteriospermia pode prejudicar a qualidade das doses de sêmen suíno. Desta forma, a adição de antimicrobianos (ATM) aos diluentes de sêmen é imprescindível para a manutenção da qualidade das doses inseminantes. Contudo, a crescente ocorrência de resistência bacteriana tem impulsionado a redução do uso de ATM na suinocultura. Nesse sentido, o armazenamento das doses inseminantes em baixas temperaturas pode ser uma alternativa para a remoção dos ATM dos diluentes comerciais. Sendo assim, no presente estudo, foram realizados dois experimentos para avaliar a qualidade espermática e a contagem de unidades formadoras de colônias (UFC/mL) de doses de sêmen suíno submetidas a baixas temperaturas de armazenamento, na ausência ou presença de ATM. No experimento 1, as motilidades (total e progressiva) das doses com ATM foram maiores conforme aumentou a temperatura de armazenamento (P<0,01). Nas doses sem ATM, as motilidades foram inferiores nas mantidas a 5 °C do que nas demais (P<0,05). O número de UFC/mL foi menor nas doses sem ATM mantidas a 5 e 10 °C do que a 17 °C (P<0,05), mas não houve diferença entre as temperaturas de armazenamento nas doses com ATM (P>0,05). As integridades de acrossoma e de membrana plasmática não foram afetadas (P>0,05) pelo uso de ATM, mas foram influenciadas pela temperatura de armazenamento (P<0,0001) No experimento 2, os machos foram categorizados em BONS e RUINS de acordo com a motilidade progressiva das doses com ATM armazenadas a 5 °C nas 120 h, sendo investigado o efeito dessas categorias sobre as variáveis estudadas. A motilidade total das doses armazenadas a 17 °C foi superior à das mantidas a 5 °C diluídas sem ATM (P<0,05). Os percentuais de motilidade progressiva e de acrossomas normais foram superiores nas doses mantidas a 17 °C do que nas mantidas a 5 °C, com ou sem ATM (P<0,05). O número de UFC/ml foi maior nas doses diluídas sem ATM do que nas demais (P<0,05). Após a categorização dos machos, as motilidades (total e progressiva) foram maiores nos machos BONS do que nos RUINS (P<0,05), sem diferença significativa (P>0,05) nas integridades (acrossomal e de membrana plasmática). Apesar de a qualidade espermática ter sido afetada negativamente pelas baixas temperaturas, o armazenamento das doses de sêmen suíno a 5 °C é possível, uma vez que foi mantida a viabilidade espermática in vitro, por até 5 dias, acima do nível mínimo considerado adequado para a inseminação artificial. Contudo, o uso de doses sem antimicrobianos ainda precisa de otimização, posto que que as baixas temperaturas de armazenamento reduzem, mas não inibem por completo o crescimento bacteriano.Bacteriospermia can impair boar semen dose quality. Thus, the addition of antibiotics (ATB) is indispensable for maintaining semen doses quality. Nevertheless, growing bacterial resistance occurrence have had driven to a reduction in use of ATB in pig industry. In this sense, storage of semen doses at low temperature may be an alternative to removal ATB of commercial semen extenders. Therefore, the aim of the present study was to assess sperm quality and number of colony-forming units (CFU mL-1) in boar semen doses stored at low storage temperatures with or without ATB, in two experiments. In experiment 1, in semen doses with ATB, total and progressive motility increased as the storage temperature increased (P<0.01). In semen doses without ATB, total and progressive motility were observed to be lower when stored at 5 °C than at 10 and 17 °C (P<0.05). The number of CFU mL-1 was lower in semen doses without ATB stored at 5 and 10 °C than at 17 °C (P<0.05), but there was no difference among storage temperatures in doses with ATB (P>0.05). Acrosome and sperm membrane integrity were not influenced (P>0.05) by using ATB, but they were influenced by storage temperature (P<0,0001) In experiment 2, boars were grouped in GOOD and POOR according to progressive motility in doses stored for up to 120 h at 5 °C. So, the effect of this classification on assessed variables, was investigated. Total motility was higher in doses stored at 17 °C than in doses without ATB stored at 5 °C (P<0.05). The percentages of progressive motility and normal acrosomes were higher in doses stored at 17 °C than in doses stored at 5 °C, with or without ATB (P<0.05). The number of CFU mL-1 was higher in doses without ATB than in remaining ones (P<0.05). Total and progressive motility were observed to be higher in GOOD than in POOR boars (P<0.05). There was no difference between groups of boars in acrosome and membrane integrity (P>0.05). Despite sperm quality was negatively affected by low temperatures, the storage of boar semen doses at 5 °C is possible, since sperm viability in vitro was maintained for up to 5 days, fulfilling the requirements of semen quality to be used in artificial insemination. Nevertheless, the use of semen doses without ATB will need optimization, since low storage temperatures decreased bacterial growth, but not completely inhibit it.
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Hussy, Ines. "Mesophilic fermentative hydrogen production from biomass." Thesis, University of South Wales, 2005. https://pure.southwales.ac.uk/en/studentthesis/mesophilic-fermentative-hydrogen-production-from-biomass(c099e92e-5777-48e9-bf1f-a1f72d91254e).html.
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Hydrogen is considered a possible alternative to fossil fuels. Hydrogen can be produced through dark fermentation with 1 mol hexose yielding a maximum of 4 mol hydrogen in association with acetate production, and 2 mol hydrogen in association with butyrate production. However, an economically and technically feasible process is yet to be established. So far research into fermentative hydrogen production has focused on pure and soluble carbohydrates, particularly glucose. To reduce substrate costs, use of more complex low-cost co- and waste products of the food industry or biomass crops which have undergone minimum pre-treatment would be desirable. Also, whilst much research to date has focused on use of pure bacterial strains, an easily obtainable mixed microflora would be preferable to avoid costs of substrate sterilisation. Therefore this research project focused on fermentative hydrogen production from three abundant (in the UK) low cost substrates, namely a wheat starch co-product, sugarbeet and perennial ryegrass. Anaerobic digester sludge obtained from the local sewage works was used as inoculum in a continuously stirred tank reactor. Production of hydrogen and other fermentation products was measured to gain information about the main metabolic pathways used. To lower hydrogen partial pressure the reactor was sparged with nitrogen and the effect on hydrogen production observed. It was demonstrated that stable fermentative hydrogen production from the wheat starch co-product and sugarbeet water extract was possible in continuous operation. Hydrogen production from grass extract was demonstrated in batch mode. Sparging with nitrogen significantly increased hydrogen yields, by 46% for the wheat starch co-product, by 67% for sugarbeet water extract, and by 184% for ryegrass extract. Maximum yields achieved were 1.9 mol hydrogen per mol hexose converted for 16 days on starch, 1.7 mol per mol hexose converted for 5 days on sugarbeet water extract and 0.8 mol hydrogen per mol hexose converted in batch from grass extract. Therefore up to 48% of the maximum theoretical hydrogen yield was produced. Various factors were identified as preventing higher hydrogen yields. Hydrogen production was more closely related to butyrate than acetate concentration. Also, lactate, ethanol and propionate, which are products of carbohydrate fermenting metabolic pathways that do not produce hydrogen, were detected, as were signs of hydrogen consuming homoacetogenesis in continuous operation.
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He, Lin. "Studies on xylan depolymerisation by the mesophile Streptomyces A451." Thesis, Open University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303667.
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Giovannini, Fabio. "Chirale Synthesebausteine durch enantioselektive Reduktion mit mesophilen und thermophilen Mikroorganismen /." [S.l.] : [s.n.], 1986. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=8004.
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Massanet-Nicolau, Jaime. "Mesophilic fermentative hydrogen production from sewage biosolids." Thesis, University of South Wales, 2009. https://pure.southwales.ac.uk/en/studentthesis/mesophilic-fermentative-hydrogen-production-from-sewage-biosolids(45d910c7-f8d1-4c9d-bc46-ca0b80de8361).html.
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The increasing cost of fossil fuels, combined with concerns about their impact on our environment has led to a renewed interest in hydrogen as a clean, sustainable, alternative energy vector. Using sewage biosolids as the substrate for fermentative hydrogen production offers several advantages over the use of other biomass sources. It is available at little or no cost and is abundant, being produced wherever there are human settlements, with 1.3 million tonnes (dry solids) per year currently being produced in the U.K alone. This research demonstrated the feasibility of hydrogen production from sewage biosolids via anaerobic fermentation. To do this a number of issues specifically relating to the nature of sewage biosolids had to be addressed. Firstly, the solids content and rheology made automatic feeding difficult. The feedstock also contained high levels of indigenous microorganisms and a high ratio of insoluble to soluble carbohydrate. To address these challenges, a novel reactor design using wide bore tubing and computer controlled pumping equipment was successfully used to construct a working continuously fed bio-reactor. A combination of heat treatment at 70°C for one hour and pre-treatment with a commercially available food processing enzyme mixture was found to be the most efficient method of inactivating competing microorganisms and improving substrate quality. Hydrogen was successfully produced via batch fermentation of primary sewage biosolids which had undergone heat treatment and enzymatic digestion. When fermentation took place at pH 5.5 a peak hydrogen production rate of 3.75 cm3 min"1 was observed. At this pH the hydrogen yield was 0.37 mol H2 mol~ : carbohydrate, equivalent to 18.14 L H2 kg"1 dry solids. Fermentative hydrogen production from sewage biosolids was also demonstrated in a five litre, continuously fed bio-reactor for the first time. A comparison of different hydraulic retention times showed that hydrogen production was most stable at a HRT of 24 hours. A hydrogen producing fermenter was successfully linked to a methanogenic bio-reactor in a two stage digestion process.
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Dietrich, Jochen [Verfasser]. "Thermische Inaktivierung von Bakteriophagen der mesophilen und thermophilen Milchsäurebakterien / Jochen Dietrich." Kiel : Universitätsbibliothek Kiel, 2008. http://d-nb.info/1019669020/34.
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Fritsch, Bernhardt Markus. "Versuche zur Intensivierung der fermentativen Wasserstoffproduktion mesophiler Clostridien durch verfahrenstechnische Massnahmen." Göttingen Sierke, 2009. http://d-nb.info/997098759/04.
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GonzaÌlez, Mariana Valeria. "Enhancing gas production in mesophilic anaerobic digestion (MAD)." Thesis, University of Surrey, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431096.
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Kessler, Peter S. "Nitrogen fixation in the mesophilic marine archaeon Methanococcus maripaludis /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11520.
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Ogbonna, Emmanuel. "A multi-parameter empirical model for mesophilic anaerobic digestion." Thesis, University of Hertfordshire, 2017. http://hdl.handle.net/2299/17467.
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Anaerobic digestion, which is the process by which bacteria breakdown organic matter to produce biogas (renewable energy source) and digestate (biofertiliser) in the absence of oxygen, proves to be the ideal concept not only for sustainable energy provision but also for effective organic waste management. However, the production amount of biogas to keep up with the global demand is limited by the underperformance in the system implementing the AD process. This underperformance is due to the difficulty in obtaining and maintaining the optimal operating parameters/states for anaerobic bacteria to thrive with regards to attaining a specific critical population number, which results in maximising the biogas production. This problem continues to exist as a result of insufficient knowledge of the interactions between the operating parameters and bacterial community. In addition, the lack of sufficient knowledge of the composition of bacterial groups that varies with changes in the operating parameters such as temperature, substrate and retention time. Without sufficient knowledge of the overall impact of the physico-environmental operating parameters on anaerobic bacterial growth and composition, significant improvement of biogas production may be difficult to attain. In order to mitigate this problem, this study has presented a nonlinear multi-parameter system modelling of mesophilic AD. It utilised raw data sets generated from laboratory experimentation of the influence of four operating parameters, temperature, pH, mixing speed and pressure on biogas and methane production, signifying that this is a multiple input single output (MISO) system. Due to the nonlinear characteristics of the data, the nonlinear black-box modelling technique is applied. The modelling is performed in MATLAB through System Identification approach. Two nonlinear model structures, autoregressive with exogenous input (NARX) and Hammerstein-Wiener (NLHW) with different nonlinearity estimators and model orders are chosen by trial and error and utilised to estimate the models. The performance of the models is determined by comparing the simulated outputs of the estimated models and the output in the validation data. The approach is used to validate the estimated models by checking how well the simulated output of the models fits the measured output. The best models for biogas and methane production are chosen by comparing the outputs of the best NARX and NLHW models (each for biogas and methane production), and the validation data, as well as utilising the Akaike information criterion to measure the quality of each model relative to each of the other models. The NLHW models mhw2 and mhws2 are chosen for biogas and methane production, respectively. The identified NLHW models mhw2 and mhws2 represent the behaviour of the production of biogas and methane, respectively, from mesophilic AD. Among all the candidate models studied, the nonlinear models provide a superior reproduction of the experimental data over the whole analysed period. Furthermore, the models constructed in this study cannot be used for scale-up purpose because they are not able to satisfy the rules and criteria for applying dimensional analysis to scale-up.
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Pace, Arianna. "Analysis of thermophilic and mesophilic proteins through contact map networks." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13540/.
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In questa tesi si affronta lo studio di proteine termofile e mesofile con un approccio a network, con lo scopo di cercarne differenze strutturali che giustifichino la minore termolabilità delle proteine termofile.
Applicare la teoria dei grafi allo studio delle proteine significa modellizzarne la struttura 3D con una matrice 2D, la mappa di contatto proteica, operando una compressione dell'informazione. La perdita di dettaglio è compensata dall'ottenimento di un oggetto matematico facilmente trattabile con una chiara interpretazione fisica. In questa tesi è stato scelto di concentrarsi sulle proprietà spettrali del suo Laplaciano in quanto queste sono strettamente legate alle proprietà vibrazionali del sistema. L'ipotesi è che si possa trovare così una differenza tra proteine termofile e mesofile in quanto, secondo l'ipotesi di stati equivalenti, si suppone che una proteina termofila a temperatura ambiente sia più rigida di una mesofila e che queste abbiano una flessibilità simile solamente alle loro rispettive temperature ottimali.
Il database analizzato è stato costruito come una serie di coppie di proteine omologhe, una mesofila e una termofila. Questo permette di cercare differenze tra proteine simili, le cui differenze ci si aspetta siano dovute agli adattamenti per sopravvivere in habitat con diverse temperature. Su questo dataset sono state effettuate sia misure strutturali più tradizionali, sia è stato studiato lo spettro del Laplaciano delle loro mappe di contatto. Se i primi non hanno presentato differenze significative tra i due gruppi di proteine, un risultato interessante è stato ottenuto proprio con l'approccio a network. I primi autovalori del Laplaciano, associati quindi con basse frequenze di vibrazione, riescono a discriminare proteine termofile e mesofile, in oltre il 65% delle coppie - da confrontare con percentuali di discriminazione in letteratura recente che, utilizzando solo proprietà strutturali delle proteine, non arrivano al 60%.
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鄺天生 and Tin-sang Kwong. "Anaerobic degradation of particulate starch in different reactors under mesophilic conditions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31213182.
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Dinsdale, Richard Mark. "The mesophilic and thermophilic anaerobic digestion of instant coffee waste waters." Thesis, University of South Wales, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265688.
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Kwong, Tin-sang. "Anaerobic degradation of particulate starch in different reactors under mesophilic conditions /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1478693X.
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Sands, Eric R. "Cloning and Expression of Thermophilic, Mesophilic, and Psychrophilic Zn2+ Transporting ATPases." Digital WPI, 2006. https://digitalcommons.wpi.edu/etd-theses/699.
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Protein folding and stability are essential for protein function. Changes in these characteristics can lead to altered physiological states and to the development of certain pathologies. While extensive research has focused on the stability of soluble proteins, membrane protein stability has received much less attention. Understanding the stability of membrane proteins can provide insight into folding mechanisms and the etiology of various pathologies. The purpose of this project is to prepare molecular tools to perform comparative studies of homologous membrane proteins that are found in various environments. To this end, thermophilic (Pyrococcus abyssi), mesophilic (Escherichia coli), and psychrophilic (Exiguobacterium 255-15) transmembrane Zn2+ transporting ATPases were cloned, expressed, and functionally characterized to correlate thermostability with optimal functional temperatures. In addition, the lipid environments and composition (rigid or fluid lipids) may also be involved in determining the stability of membrane proteins. Toward exploring the role of extremophilic lipids, Archaeoglobus fulgidus and Thermotoga maritima were grown and lipids were extracted. Availability of these molecular tools will enable physical-chemical studies toward understanding the structural factors that determine functional stability.
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Ngoma, I.-Muaka Emmanuel. "Investigating the effect of acid stress on selected mesophilic bioleaching microorganisms." Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/917.
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Thesis submitted in accomplishment of the requirements of the
Magister Technologiae in Engineering degree,
Department of Chemical Engineering,
Cape Peninsula University of Technology
2015Heap bioleaching is a microbially-assisted hydrometallurgical metal extraction process in which metals are solubilised from low grade ore by ferric iron and acid leach agents. Particularly for low grade ores, heap bioleaching provides several advantages over conventional technologies, it is simpler and safer to operate with low capital and operation cost and acceptable recoveries. Key challenges with heap bioleaching systems include the need to minimise leach durations and optimise both rate and extent of metal recovery. There is limited understanding of the sub-processes involved in microbially assisted bioheap leaching (nutrient transport, microorganisms attachment to mineral, effects of metal concentration on microorganisms viability, …). Mineral ore agglomeration is a pre-treatment process typically carried out in the setup of the bioheap operation to dissolve metal oxide residue, neutralise acid consuming gangue, prepare agglomerates of the mixed particle size fraction to optimise heap permeability, prepare the ore surface for microbial attachment and optimise moisture content and mineral exposure to leaching reactions. Most agglomeration processes are carried out with an acidic solution. This may create an acid stress condition for the bioleaching microorganisms when inoculated into the operation. This is particularly relevant when the inoculum is introduced during the agglomeration process and may remain under the highly acidic conditions for a protracted time. However, quantitative data on the recommended acid concentration during agglomeration processes is very limited and is dependent on the ore treated. Similarly little is reported on the response of the acidophilic bioleaching microorganisms to acid stress. This research project contributes to the bioleaching knowledge base by providing an understanding of the effect that acid stress has on the mesophilic species typically implicated in mineral sulphide bioleaching as a function of acid concentration (and resulting acidity) and duration of exposure. The study addresses the following specific key factors: The effect of acid stress due to acid concentration and exposure time on performance on mesophile microorganisms in terms of the microbial and ferrous iron oxidation. The interaction of acidity and exposure time with respect to microbial stress on the mesophilic bioleaching system performance. The nature of the stress response observed i.e. only the lag period or also the rate of ferrous iron and sulphur oxidation on the initiation of the leaching process. The observed effects on microbial activity mediated through the number of active cells or through the activity of these cells. Quick fit stirred tank reactors (STR) containing 3% pyrite concentrate and 1 litre Norris media (Norris, 1983), aerated with 2 L.min-1 compressed air and stirred at 550 rpm were inoculated with a mixed mesophilic culture mainly Acidithiobacillus ferrooxidans, Acidiplasma cupricumulans, Ferroplasma acidiphilum, and predominantly Leptospirillum ferriphilum following its pre-stress at 0.34M, 0.51M and 0.68M acid (H2SO4), whilst operating as a batch system. A Control, inoculated with an un-stressed culture, was run concurrently. The cultures were subjected to these acid stresses for a period of one hour, three hours and 24 hour and assessed for microbial growth and activity, leaching performance and microbial speciation. Findings showed an increasing period necessary for microbial recovery with increased acid stress and increased time exposure. A similar leaching performance to the Control were recorded soon after the cultures recovered from the stress when the acid concentrations used were low, but the highest acid concentration (0.68M) combined with the longer exposure time (24 h) compromised the overall leaching performance and the required time of recovery was extended to as high as 200 h. Equally the microbial growth rates were similar to that of the Control culture following the recovery period. The yield in terms of microbial cells produced per kg iron oxidised decreased with increased acid stress but not necessarily with increased exposure time. The extent of iron solubilisation, at the time the Control achieved its highest solubilisation, decreased with both increases in acid stress concentrations and in exposure time. Microbial speciation indicated that four of the initial six species in the mixed culture were sensitive to acid stress. Only three species survived the stress in the early stages of the experiment and one specie disappeared during the course of the leaching experiment leaving just two species surviving. Of the two surviving species, Fe. acidiphilum and L. ferriphilum, the latter dominated to a final ratio of 99% to 1%. Some recommendations have been made for future studies, namely: Acid stress effects should be tested on simulated heap leaching experiments using agglomerated ore. Acid concentration and exposure time should be increased to assess the extent of microbial recovery and acid tolerance levels. Similar experiment should be conducted using moderate thermophile and thermophile cultures. A conglomerate of a more defined mixed culture should be used to assess the acid resistant species. Physico-chemical conditions resulting from the acid agglomeration, such as shear stress, increase temperature, radiation should be considered to be assessed further.
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Staffa, Wilma. "Salmonella Typhimurium DT104 aus einer mesophilen Biogasanlage Überlebenszeiten und experimentelle Inaktivierung durch ausgewählte organische Säuren." Doctoral thesis, Universitätsbibliothek Leipzig, 2004. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-37631.
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Aus Materialien einer mesophilen Biogasanlage wurden Untersuchungen zur natürlichen Inaktivierung von Salmonellen durchgeführt. In dieser Biogasanlage werden zur alternativen Energiegewinnung im zweistufigen Prozess Rinderflüssigmist, Hühnerkot und Fettabscheiderinhalte fermentiert. Insgesamt konnten in den Jahren 1997-2000 zwölf verschiedene Salmonella-Serovare (z. B. S. Enteritidis, S. Agona, S. Hadar) in den Ausgangsmaterialien, im Fermentationsmaterial und im fertigen Fermentationsprodukt isoliert werden. Salmonella-positiv waren die Proben zu 95,5% (n = 22) aus der Rindergülle, zu 69,2% (n =13) aus dem Fermenter I, zu 50% (n = 20) aus dem Fermenter II, zu 77,3% (n = 22) aus der Lagune und zu 40% (n = 10) aus dem Fettabscheider. Als Quellen der Salmonellen werden die Gülle der Milchviehanlage (besonders für den Impfstamm) sowie Fettabscheiderinhalte diskutiert. Nach einer Infektion von Rindern mit S. Typhimurium in der gülleliefernden Milchviehanlage war nach der Vakzinierung der Kälber der Zoosaloral®-Impfstamm (LT: DT009) in der Gülle häufig nachweisbar. Bei 13 Untersuchun-gen wurde der Impfstamm zwölfmal in der Gülle der Milchviehanlage, einmal im Fermentationsprodukt der Biogasanlage und in fünf Proben aus der Lagune isoliert. Im Laboratorium wurde das Absterben von S. Typhimurium DT104 in fermen-tierender Rindergülle bei Lagerungstemperaturen von 7°C, 22°C und 37°C un-tersucht. Nach durchschnittlich 10 Tagen waren bei 37°C dies entspricht etwa der Betriebstemperatur einer mesophilen Biogasanlage keine Salmonellen nachweisbar. Bei einer Temperatur von 22°C überlebten die Salmonellen neun Wochen, bei 7°C überlebten sie mehr als 52 Wochen. Der mikrobiologische Abbau von Biomasse führt zur Aufspaltung der Makro-moleküle und danach zur Bildung von Karbonsäuren. Nach der Analyse orga-nischer Säuren aus Rindergülle und Cosubstraten wurden Konzentrationen dieser Säuren gegen S. Typhimurium DT104 experimentell geprüft. Es wurde der Einfluss von Ameisen-, Essig-, Propion-, Butter-, Isobutter-, Valerian-, Iso-valeriansäure auf die Inaktivierung von S. Typhimurium DT104 untersucht. In Versuchen mit den Einzelsäuren und Dosen der Salmonellen, die über den Gehalten nativer Gülle lagen, konnte eine Inaktivierung erst bei Konzentratio-nen von 10 bis 40 g/l erzielt werden. Da diese Konzentrationen laut der zu Grunde gelegten Gülleanalyse in den jeweiligen Einzelfällen nicht erreicht wurden, erfolgte die Prüfung der Säuren gegenüber den Salmonellen im Kom-plex. Dazu wurde ein Säuregemisch hergestellt, das den ermittelten Konzentra-tionen der Säuren in der Rindergülle plus Cosubstraten entspricht und auf ei-nen pH-Wert von 7,3 eingestellt. In dieser Säurelösung wurden Salmonellen täglich um durchschnittlich 0,5 Zehnerpotenzen reduziert und in drei Ver-suchsansätzen innerhalb von durchschnittlich 17 Tagen inaktiviert. Mit diesen Daten wird der Einfluß von in der Gülle vorkommenden Konzentrationen or-ganischer Säuren auf S. Typhimurium DT104 erstmals quantifiziert. Aus den Untersuchungen wird der Schluß gezogen, dass für das Absterben von S. Typhimurium DT104 während der 24 bis 33 Tage andauernden natürlichen Fermentation der Gülle in der Biogasanlage der Anstieg und der Einfluß der Karbonsäuren sehr wesentlich ist. Die nach der Vakzinierung der Kälber mit dem Lebendimpfstoff Zoosaloral® ausgeschiedenen Salmonellenimpfstämme waren auch nach Passage der Bio-gasanlage durch ihr auxotrophes Verhalten sicher von Wildstämmen zu unter-scheiden. Bei der Untersuchung von Gülle aus mit Salmonella-Lebendvakzinen geimpften Rinderbeständen ist das Mitführen des Bovisal-Diagnostikums® zu empfehlen. Bei den natürlich vorkommenden Salmonellen-Serovaren wurden zahlreiche Resistenzen gegenüber unterschiedlichen Antibiotika festgestellt. Die Zoosalo-ral®-Impfstämme wiesen nach der Passage der Biogasanlage keine veränderten Resistenzen auf. Die Zoosaloral®-Impfstämme sind resistent gegen Spectinomy-cin, Erythromycin und PenicillinWe investigated the natural inactivation of Salmonella in the stuff of a meso-philic biogas plant where cattle slurry, poultry waste and fat separator contents are fermented in a two-step process for the use of alternative energy recovery. From 1997 to 2000 we isolated 12 different Salmonella serovars (e. g. S. Enteriti-dis, S. Agona, S. Hadar) in the native sludge, in the fermenter material and in the fermentation product. The following parts of the samples were Salmonella-positive: cattle slurry 95,5% (n = 22), fermenter I 69,2% (n =13), fermenter II 50% (n = 20), storage tank 77,3% (n = 22), and fat separator 40% (n = 10). As source of the Salmonella we assume the slurry of the dairy cattle farm (esp. in the case of vaccine strains) and the fat separator contents. After an infection of cattle with S. Typhimurium in the sludge-producing farm and vaccination of calves with Zoosaloral® the vaccine strain (LT: DT009) was frequently found in the slurry. In the course of 13 tests we isolated the vaccine strain in 12 samples of the biogas plant slurry, in one sample of the fermenta-tion product and in 5 samples of the storage tank. In laboratory investigations we studied the inactivation of S. Typhimurium DT104 in fermented cattle slurry at storage temperatures of 7°C, 22°C, and 37°C. After a mean storage time of 10 days at 37°C (i.e. the working tempera-ture of the biogas plant) all Salmonella were inactivated. At 22°C they survived nine weeks, at 7°C more than 52 weeks. The microbiologic degradation causes the splitting of macromolecules and the formation of free volatile acides (VFA). After analysis of the VFA in cattle slurry and cosubstrates we tested different concentrations of formic, acetic, propionic, butyric, isobutyric, valerianic, and isovalerianic acid. In tests with the single acids and Salmonella concentrations higher than in native slurry an inactivation was achieved at acid concentrations between 10-40 mg/l. Because acid concen-trations in native sludge are lower, we examined an acid mixture with acid con-centrations equivalent to cattle slurry/cosubstrate at pH 7,3. In the mixture Salmonalla were daily reduced about 0,5 orders and inactivated in an average of 17 days. These data quantify the influence of VFA concentrations in slurry for the first time. We concluded that the increase and the influence of VFA are very important for the inactivation of S. Typhimurium DT104 during the 24-33 days of slurry fer-mentation in the biogas plant. After vaccination of calves with the live vaccine Zoosaloral® the excreted Salmonella vaccine strains could be distinguished after the passage of the biogas plant by their auxotrophy from wild strains. We rec-ommend the use of Bovisaloral-Diagnostikum® for investigations of slurry from cattle vaccinated with Salmonella live vaccine. The natural Salmonella serovars were resistant against numerous antibiotics. The Zoosaloral® vaccine strains showed no deviating resistances after passag-ing the biogas plant. The Zoosaloral® vaccine strains were spectinomycine-, erythromycine- and penicilline-resistent
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Vollstedt, Angela. "Sekretorische Gewinnung von Enzymen aus dem thermoalkaliphilen Bakterium Anaerobranca gottschalkii im mesophilen Wirt Staphylococcus carnosus." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=971438463.
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Staffa, Wilma. "Salmonella typhimurium DT104 aus einer mesophilen Biogasanlage: Überlebenszeiten und experimentelle Inaktivierung durch ausgewählte organische Säuren." [S.l. : s.n.], 2003. http://dol.uni-leipzig.de/pub/2003-44.
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Young, Bradley. "Enhancement of the Mesophilic Anaerobic Co-digestion of Municipal Sewage and Scum." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23530.
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Scum is an integral component of solids management in MWWTP and is composed of fats, oils, grease and other entrained floatable materials that are collected during primary clarification. Lab scale BMP tests showed the addition of 14.5 g VS/L of scum exhibited the greatest increase in biogas production of 1.6 times per g VS added compared to the control, while a higher additional scum loading of 33.7 g VS/L reduced the biogas yield to 32% of the control reactor. Lab scale semi-continuous digestion measured the effects of scum loading and temperature of pretreatment in the scum concentrator. At 15 d and 20 d HRTs the greatest observed improvement in biogas was achieved by adding 3% scum by volume and pretreating the scum at 70°C in a scum concentrator with respective improvements of 24% and 16%.
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Ramachandran, Umesh. "Proteomics and metabolism of the mesophilic cellulolytic bacterium, Clostridium termitidis strain CT1112." Elsevier, 2008. http://hdl.handle.net/1993/22211.
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Consolidated bioprocessing, a method that involves cellulase production, substrate hydrolysis, and fermentation all in one step, requires lower energy input and aims at achieving reduced biofuel production costs than traditional processes. It is an economically appealing strategy for the efficient production of biofuels such as ethanol or H2. At present, the yields of fermentative hydrogen and ethanol production are less than the theoretical maximum and vary between anaerobic Clostridia due to the presence of highly branched metabolic pathways. With the recent advancements in ‘Omic technologies, the selected cellulolytic species, in this case, C. termitidis, was extensively studied to identify the key enzymes that are involved in hydrogen and ethanol synthesis pathways in both the genome and proteome under different culture conditions. Metabolic characterization involving growth and end-product synthesis patterns were performed on 2 g L-1 cellobiose and α-cellulose under batch conditions to determine its metabolic potential for hydrogen and/or ethanol production. Initial characterization has shown the ability of C. termitidis to produce hydrogen, ethanol, and various other end-products on the two susbtrates. Continous N2 sparging in the pH-controlled bioreactors with cellobiose and α-cellulose showed a consistent increase in the H2 synthesis and lowered ethanol production compared to batch studies, with the H2 yields of 1.03 and 1.34 mol product per mol hexose equivalent added, respectively. Shotgun 2-D proteome analyses were performed to compare cellulose versus cellobiose grown cultures across exponential and stationary phases of growth. Most of the glycolytic proteins were detected in the proteome with some exceptions and no significant change was observed across both growth conditions. Hydrogen synthesis was regulatd via PFOR and ferredoxin-dependent hydrogenase, where as ethanol synthesis was regulated primarily via bifunctional AdhE activity. Proteomic analyses of C. termitidis cultured on hexose sugars in the absence of xylose suggested possible sequential utilization of xylose and cellobiose for the first time. Putative proteins consistent with xylose fermentation were observed at high levels. The hypothesis that C. termitidis can sequentially utilize xylose and cellobiose was further validated using batch fermentations tests on pure (xylose, cellobiose, xylan) and mixed substrates (xylose + cellobiose).
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鍾偉聰 and Wai-chung Denis Chung. "Comparison of performance of thermophilic and mesophilic UASB reactorstreating protein-rich wastewater." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31215221.
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Deveci, Haci. "Bacterial leaching of complex zinc/lead sulphides using mesophilic and thermophilic bacteria." Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341175.
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Yang, Fan. "Mesophilic anaerobic digestion conducted in single unit reactor at increasing ammonia concentrations." Thesis, Högskolan i Halmstad, Bio- och miljösystemforskning (BLESS), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-16920.
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The use of mesophilic anaerobic digestion for treatment of organic wastes is a growing biotechnology for sustainable energy supply. Ammonia inhibition is a major problem in anaerobic digestion mainly when digestion of nitrogen-rich substrates such as livestock wastes and manure occurs. This paper provides a summary of research conducted on ammonia inhibition of the anaerobic process. An experiment with mesophilic digestions of swine manure was conducted in single unit reactors, which were controlled under different ammonia concentrations by addition of NH4Cl in different amounts. From the experimental results, it was shown that NH4Cl could be an effective chemical agent for removing foam and scum in the digester. Methane production was decreased with the increasing NH4Cl addition until a collapse was observed between 11.2 g NH4+-N/l and 13.2 g NH4+-N/l. Contrary to the findings in thermophilic digestion, a dysfunction of acidogenesis was also observed since both gas and methane production was delayed with increasing NH4Cl addition. These findings suggest different ammonia inhibition principles in mesophilic and thermophilic digestion. It was further indicated that methanogenesis could produce a high percentage of methane although gas production was inhibited.
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Dessi, Paolo. "Mesophilic and thermophilic biohydrogen and bioelectricity production from real and synthetic wastewaters." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC2056/document.
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La fermentation sombre et les piles à combustible microbiennes (MFC) sont deux technologies émergentes respectivement pour la conversion biologique de l'énergie chimique des composés organiques en hydrogène (H2) et en électricité. En raison des avantages cinétiques et thermodynamiques, la température élevée peut être la clé pour augmenter à la fois la production d'H2 de fermentation sombre et la production d'électricité dans les MFC. Par conséquent, cette thèse se concentre sur la manière dont la température influence la production biologique de H2 et d'électricité à partir d'eaux usées contenant du carbone organique. Deux inocula traités thermiquement (à boues activées fraîches et digérées) ont été comparés pour la production de H2 à partir de xylose à 37, 55 et 70 °C. A la fois à 37 et 55 °C, on obtient un meilleur rendement en H2 par les boues activées fraîches comparé aux boues digérées tandis qu'un très faible rendement en H2 est obtenu par les deux inocula à 70 °C. Ensuite, quatre prétraitements d'inoculum différents (chocs acides, alcalins, thermiques et de congélation) ont été évalués pour créer une efficace communauté productrice de H2 mésophile (37 °C) ou thermophile (55 °C). Les chocs acides et alcalins ont sélectionné des micro-organismes producteurs de H2, appartenant aux Clostridiaceae, au détriment des bactéries produisant du lactate, ce qui a donné respectivement le rendement en H2 le plus élevé à 37 et 55 °C. Bien que le choc thermique ait abouti à un faible rendement en H2 dans un seul lot, il a été montré que la production de H2 par les boues activées fraîches traitées thermiquement augmentait dans l'expérience avec quatre cycles consécutifs. Des boues activées fraîches et traitées thermiquement ont été sélectionnées comme inoculum pour la production continue de H2 à partir d'une eau usée synthétique contenant du xylose dans un réacteur à lit fluidisé (FBR) mésophile (37 °C) et thermophile (55-70 °C, augmenté par étapes). Un rendement en H2 plus élevé a été obtenu dans le FBR thermophile que dans le FBR mésophile. En outre, la production de H2 à 70 °C, qui a échoué dans l'étude précédente, a été couronnée de succès dans le FBR, avec un rendement stable de 1.2 mol H2 mol-1 xylose. La température de fonctionnement de 70 °C s'est également révélée optimale pour la production de H2 à partir d'eaux usées thermomécaniques (TMP) dans un incubateur à gradient de température, car la culture en batch à 70 ° C. Une approche de l'ARN a été utilisée pour étudier la structure et le rôle des communautés microbiennes attachées à l'anode, attachées à la membrane et planctoniques dans un MFC mésophile (37 °C) et thermophile (55 °C) alimenté au xylose. Une communauté anodine dominée par Geobacteraceae a soutenu la production d'électricité à 37 °C, alors que l'établissement de micro-organismes méthanogènes et H2 oxydants a entraîné une faible production d'électricité à 55 °C. Cependant, le développement d'une communauté exoélectrogène thermophile peut être favorisé en appliquant une stratégie de démarrage qui comprend l'imposition d'un potentiel négatif à l'anode et l'inhibition chimique des méthanogènes. Une communauté exoélectrogénique mésophile a également été montré pour produire de l'électricité à partir d'eaux usées de TMP dans un MFC à flux ascendant exploité à 37 °C. En conclusion, une production de H2 plus élevé et plus stable peut être obtenu dans une fermentation sombre thermophile plutôt que mésophile. La fermentation sombre à 70 °C est particulièrement appropriée pour le traitement des eaux usées de TMP car elle est libérée à haute température (50-80 °C) et pourrait être traitée sur site. Les eaux usées de TMP peuvent également être utilisées comme substrat pour la production d'électricité dans les MFC mésophiles. La production d'électricité dans les MFC thermophiles est faisable, mais l'enrichissement des micro-organismes exoélectrogènes thermophiles peut nécessiter une longue période de démarrageDark fermentation and microbial fuel cells (MFCs) are two emerging technologies for biological conversion of the chemical energy of organic compounds into hydrogen (H2) and electricity, respectively. Due to kinetic and thermodynamic advantages, high temperature can be the key for increasing both dark fermentative H2 production and electricity production in MFCs. Therefore, this thesis focuses on delineating how temperature influences biological production of H2 and electricity from organic carbon-containing wastewaters. Two heat-treated inocula (fresh and digested activated sludge) were compared, for H2 production from xylose at 37, 55 and 70 °C. At both 37 and 55 °C, a higher H2 yield was achieved by the fresh than digested activated sludge, whereas a very low H2 yield was obtained by both inocula at 70 °C. Then, four different inoculum pretreatments (acidic, alkaline, heat and freezing shocks) were evaluated for creating an efficient mesophilic (37 °C) or thermophilic (55 °C) H2 producing community. Acidic and alkaline shocks selected known H2 producing microorganisms belonging to Clostridiaceae at the expenses of lactate producing bacteria, resulting in the highest H2 yield at 37 and 55 °C, respectively. Although a heat shock resulted in a low H2 yield in a single batch, H2 production by the heat-treated fresh activated sludge was shown to increase in the experiment with four consecutive batch cycles.Heat-treated fresh activated sludge was selected as inoculum for continuous H2 production from a xylose-containing synthetic wastewater in a mesophilic (37 °C) and a thermophilic (55-70 °C, increased stepwise) fluidized bed reactor (FBR). A higher H2 yield was obtained in the thermophilic than in the mesophilic FBR. Furthermore, H2 production at 70 °C, which failed in the earlier batch study, was successful in the FBR, with a stable yield of 1.2 mol H2 mol-1 xyloseadded. Operation temperature of 70 °C was also found optimal for H2 production from thermomechanical pulping (TMP) wastewater in a temperature gradient incubator assay.A RNA approach was used to study the structure and role of the anode-attached, membrane-attached and planktonic microbial communities in a mesophilic (37 °C) and a thermophilic (55 °C) two-chamber, xylose-fed MFC. An anode attached community dominated by Geobacteraceae sustained electricity production at 37 °C, whereas the establishment of methanogenic and H2 oxidizing microorganisms resulted in a low electricity production at 55 °C. However, the development of a thermophilic exoelectrogenic community can be promoted by applying a start-up strategy which includes imposing a negative potential to the anode and chemical inhibition of methanogens. A mesophilic exoelectrogenic community was also shown to produce electricity from TMP wastewater in an upflow MFC operated at 37 °C. In conclusion, a higher and more stable H2 yield can be achieved in thermophilic rather than mesophilic dark fermentation. Dark fermentation at 70 °C is particularly suitable for treatment of TMP wastewater as it is released at high temperature (50-80 °C) and could be treated on site. TMP wastewater can be also used as substrate for electricity production in mesophilic MFCs. Electricity production in thermophilic MFCs is feasible, but enrichment of thermophilic exoelectrogenic microorganisms may require a long start-up period
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Asimakopoulos, George. "Start–up of a Thermophilic Digestion of Sewage Sludge from Mesophilic Conditions." Thesis, KTH, Mark- och vattenteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199219.
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The purpose of this Master thesis is to study two different ways of start-up in anaerobic digesters under thermophilic conditions. As awareness for energy supply is growing, municipal waste water treatment uses a common treatment to stabilize sewage sludge which is called, anaerobic digestion (AD). Anaerobic digestion can transform the organic matter to combustible biogas which contains 60-70% methane. Biogas is usually referred to as a mixture of carbon dioxide (C02) and methane gas (CH4). The most common way to anaerobically treat sewage sludge at wastewater treatment plants in Sweden is on mesophilic conditions (30-40℃). Only 12 plants in the country treat sewage sludge in thermophilic conditions 50-60℃. Mesophilic digestion is considered as a more stable process but requires a longer hydraulic retention time to reach digestibility compared to thermophilic digestion. The higher temperature also enables a pathogenic destruction capacity which means that thermophilic digestion can be used as a sanitation method for sewage sludge.
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Munir, Rifat. "Cellulose hydrolysis and metabolism in the mesophilic, cellulolytic bacterium, Clostridium termitidis CT1112." PlosOne, 2014. http://hdl.handle.net/1993/30988.
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Consolidated bioprocessing (CBP) provides a cost effective cellulose processing strategy, in which enzyme production, substrate hydrolysis, and fermentation of sugars to ethanol are all carried out in a single step by microorganisms. For industrial-scale bioethanol production, CBP-enabling microbes must be able to both efficiently degrade lignocellulosic material to fermentable sugars and synthesize bioethanol with high yields. Microbes with these properties have so far not been identified. Developing naturally occurring cellulolytic isolates with CBP-relevant properties requires a comprehensive understanding of their lignocellulosic hydrolysis mechanism and metabolism. In my quest to find a suitable organism for potential use in CBP, I took to investigate the under-characterized anaerobic bacterium, Clostridium termitidis strain CT1112. C. termitidis produces fermentative hydrogen and ethanol from a variety of lignocellulose derived substrates. I sought to investigate the metabolism of C. termitidis on different substrates and the mechanisms of substrate hydrolysis using a combination of microscopy, comparative bioinformatics, and ‘Omic (transcriptomic and proteomic) analyses. Comparative bioinformatics analyses revealed higher numbers of genes encoding carbohydrate active enzymes (CAZymes) with the potential to hydrolyze a wide-range of carbohydrates, and ‘Omic analyses were used to quantify the levels of expression of CAZymes, including endoglucanases, exoglucanases, hemicellulases and cellulosomal components. While cellulases and cellulosome components were highly expressed on cellulose, xylanases and glucosidases were predominantly expressed on pentoses, and chitinases (as well as cellobiose phosphorylases) were significantly up-regulated on cellobiose. In addition to growth on xylan, the simultaneous consumption of two important lignocellulose constituents, cellobiose and xylose was also observed. The ability to metabolize both hexose and pentose sugars is a highly desirable feature of CBP-relevant organisms. Metabolic profiles in association with ‘Omics analyses showed that hexoses and pentoses are consumed via the Embden-Meyerhof-Parnas and Pentose-Phosphate pathways, respectively, and that the genome content and expression profiles dictate end-product synthesis patterns. Genes and gene-products of enzymes in central metabolism and end-product synthesis were detected in high abundance under all substrate conditions, regardless of the amounts of end-products synthesized. The capabilities described thus far, identifies C. termitidis as a strain of interest for CBP. Further studies are, however, required for its development in to an industry-ready strain for biofuel production.February 2016
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Liebeneiner, Rolf [Verfasser], and Klaus [Akademischer Betreuer] Fricke. "Leistungsfähigkeit der Trockenvergärung von nachwachsenden Rohstoffen unter thermophiler und mesophiler Prozessführung / Rolf Liebeneiner ; Betreuer: Klaus Fricke." Braunschweig : Technische Universität Braunschweig, 2010. http://d-nb.info/1175826855/34.
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Striewski, Sandra [Verfasser]. "Wechselwirkung von mechanischer Aufbereitung und biologischer Behandlung dargestellt am Beispiel der mesophilen Nassvergärung von Restabfällen / Sandra Striewski." Aachen : Shaker, 2004. http://d-nb.info/1172611890/34.
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Inman, David C. "Comparative Studies of Alternative Anaerobic Digestion Technologies." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35573.
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Washington D.C. Water and Sewage Authority is planning to construct a new anaerobic digestion facility at its Blue Plains WWTP by 2008. The research conducted in this study is to aid the designers of this facility by evaluating alternative digestion technologies. Alternative anaerobic digestion technologies include thermophilic, acid/gas phased, and temperature phased digestion. In order to evaluate the relative merits of each, a year long study evaluated the performance of bench scale digestion systems at varying solids retention times (SRT) and organic loading rates (OLR). The digesters were fed a blend of primary and secondary residuals from the Blue Plains wastewater treatment facility.
In each study phase, temperature phased anaerobic digestion was compared to single stage mesophilic digestion (the industry standard) at the same SRT. Single stage thermophilic digestion was evaluated by sampling the first thermophilic stage of the temperature phased digestion systems throughout the study. Additionally, the first phase study compared acid/gas phased digestion to temperature phased and single stage mesophilic digestion.
Results of the study demonstrated that the temperature phased digestion system consistently performed better than the other systems during each study phase by having higher volatile solids reduction (VSR), higher methane production, and lower residual biological activity. The highest observed VSR during the study (67%) occurred in a temperature phased digestion system operated at 7.5 days in each stage. Based on these results, it seems a suitable candidate for the Blue Plains digestion facility. Additionally, odor studies performed in conjunction with the research presented in this paper have shown distinct advantages for the temperature phased process.Master of Science
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Fraser, Kino Dwayne. "Increased Anaerobic Digestion Efficiency via the Use of Thermal Hydrolysis." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/33979.
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Waste sludge is frequently treated by anaerobic digestion to kill pathogens, generate methane gas and reduce odors so the sludge can be safely land applied. In an attempt to reduce sludge volumes and improve sludge dewatering properties, the use of thermal hydrolysis (TH), a sludge pretreatment method, has been adopted by numerous wastewater treatment plants, among them being the District of Columbia Water and Sewage Authority (DC WASA).
The use of anaerobic digestion in collaboration with thermal hydrolysis has been shown to increase VS removal, COD removal and biogas production. The sludge generated also dewaters to a higher cake solids than from conventional anaerobic digestion. Unfortunately, DC WASA has found that the use of thermal hydrolysis had brought about two major issues. These are: (a) does thermal hydrolysis increase destruction of fats, oils and greases compared to conventional digestion? and (b) is the mixing method used at Virginia Tech (recirculating gas mixing) capable of stripping ammonia from the digester? Therefore the main purpose of this study is to evaluate these issues which occur with the use of the thermal hydrolysis process.
Experiments were conducted in two phases. The first phase was to assess the performance of anaerobic digesters via their biogas production with and without long chain fatty acid addition and with or without thermal hydrolysis. This research was further carried out in two stages. First a mixture of unsaturated long chain fatty acids (hydrolyzed and unhydrolyzed) was used. The fatty acid mixture included oleic, linoleic and linolenic acids, which contain one, two and three double bonds, respectively.
In the second stage, the effect of a single unsaturated fatty acid (hydrolyzed and unhydrolyzed) was analyzed. If extra gas is generated, grease addition to the digesters will be implemented. If thermal hydrolysis produces more gas, the greases will be added through the thermal hydrolysis unit rather than being added directly to the digester. The results showed that addition of long chain fatty acids greatly increased gas production and the long chain fatty acids that were thermally hydrolyzed generated more gas than the untreated long chain fatty acids, although the gain was not large.
The second phase of the study was carried out by alternating the type of recirculating gas mixing (partial and continuous) in the anaerobic bioreactor. To achieve this goal, short-term anaerobic bioreactor studies were conducted by varying the frequency of the gas. The result showed that continuous gas recirculation at the bottom of the digester was responsible for stripping ammonia from the system. It appeared that up to 500 mg/L of ammonia was being stripped from the digester operating at 20 day solids retention time. This suggests that ammonia can be stripped if a reduction of ammonia in the digester was desired.
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Bivins, Jason Lee. "Changes in Dewatering Properties Between the Thermophilic and Mesophilic Stages in TPAD Systems." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/36254.
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Temperature-phased anaerobic digestion (TPAD) has become increasingly appealing in recent years due to the pathogen destruction capabilities of the system. However, there has also been concern about the dewatering properties of the sludges created by these systems. A laboratory study was conducted at Virginia Tech to determine the effect of thermophilic solids retention time (SRT) on sludge dewatering properties, to characterize system parameters associated with dewatering, and to understand the mechanisms causing changes in dewatering properties between the thermophilic and mesophilic phases. The study showed that while anaerobic digestion caused dewatering properties to deteriorate, sludges varied little with thermophilic SRT. Acidogenesis was essentially complete after 1.5 days. Subsequent mesophilic digestion resulted in little change to dewatering properties and modest reductions in conditioning doses, but substantial reductions in biopolymer (protein + polysaccharides) occurred. It appears that thermophilic anaerobic digestion creates or releases colloidal materials that cause dewatering to be poor and subsequent mesophilic digestion for 15 days does little to improve sludge properties of TPAD systems.Master of Science
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Benabdallah, El-Hadj Toufik. "Biodegradation of Organic Micropollutants in Themophilic and Mesophilic Anareobic Digestion of Sewage Sludge." Doctoral thesis, Universitat de Barcelona, 2006. http://hdl.handle.net/10803/1528.
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Nowadays, mesophilic anaerobic processes (under 35ºC) predominate but they show to be unable to accomplish the new specifications. Consequently, only the migration to higher temperature conditions, i.e. thermophilic operation, seems to be capable of producing stabilized sludge that meets the new restrictions related to the presence of harmful bacteria. In addition, the effect of anaerobic digestion on organic micropollutants has scarcely been studied. Moreover, the temperature impact on these compounds in anaerobic digestion of sewage sludge has also not been elucidated.The overall objective of this work is to study the fate of some organic micropollutants during raw sewage sludge (RSS) anaerobic digestion and the effect of thermophilic temperature conditions on treatment efficiency, when compared with mesophilic anaerobic. To this purpose, a mesophilic and thermophilic anaerobic digester were operated using Waste Activated Sludge (WAS) as inoculum and the effects of Hydraulic Retention Time (HRT) reduction and its influence on the fate of the selected organic micropollutants (namely, PAH, DEHP, AOX, PCB, NPE and LAS) were studied. Furthermore, the effect of a complementary treatment, namely the ultrasonic pretreatment, on the biodegradability of the organic feed and the behaviour of the subsequent anaerobic digestion was also examined, focussing on the micropollutants reduction.
The main conclusions of every set experimental are presented:
Start-up and HRT reduction
· The use of WAS as inoculum for anaerobic digesters start-up represents a good option specially under thermophilic conditions.
· Thermophilic anaerobic digestion is a good alternative to mesophilic digestion in order to improve specific biogas production.
· The similar values of organic matter removal (VS) registered in both digesters.
· 8 days was found to be the minimum HRT for the thermophilic digester, since VFA accumulation and pH decrease inhibited the process when working at a lower HRT.
Organic micropollutants removal
· Organic micropollutants removal efficiency was enhanced under thermophilic conditions.
· The HRT influence was clearly observed for DEHP and PCB, independently of digestion temperature. However, it was temperature dependent for PAH, AOX, LAS and espcially for NPE.
· NPE and DEHP are identified as the more recalcitrants contaminants.
· The thermophilic conditions were not ensured the sludge safety conditions for agriculture use.
· The accumulation of some compounds as NP and LCB was observed.
· NP was stated as the intermediate compound of NPEO anaerobic degradation. Moreover, LCB were generated during HCB reductive dechlorination during anaerobic digestion.
· Monitoring the metabolites of cited contaminants can be elucidated their biodegradation mechanisms and prevent any undesirable effects.
Ultrasound-anaerobic digestion combined treatment
· Organic matter removal, SBP and naphthalene removal were enhanced using the combined treatment in both digesters.
· High organic matter removal, SBP and napthalene removal was registered in the thermo-digester.
· Higher was enhancement of organic matter removal, SBP and naphthalene removal in the meso-digester than in the thermo-digester.
· Pyrene removal was nearly the same with and without pretreatment.
· It seems that the ultrasonic pretreatment affect more the mesophilic than the thermophilic digestion.
· The results obtained in this combined treatment (ultrasound + anaerobic digestion) are promising and suggest the convenience of other investigations of other combined treatments to enhance the stabilized sludge quality.
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Chung, Wai-chung Denis. "Comparison of performance of thermophilic and mesophilic UASB reactors treating protein-rich wastewater /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20665738.
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Shana, Achame. "Application of an innovative process for improving mesophilic anaerobic digestion of sewage sludge." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/809611/.
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Over the last 18 years, different sludge pre-treatment processes have been used to improve the performance of sewage sludge anaerobic digestion efficiency. Some of these pre-treatment technologies, notably the Thermal Hydrolysis Process (THP), has significantly increased the sludge throughput and allowed more efficient utilisation of treatment assets without adversely impacting the biology of the anaerobic digestion process. However, the expected increase in Volatile Solid reduction (VSr) and the consequent increase of biogas production have not been fully realised. Specifically, to address this poor performance when the THP process is used and to overcome its limitations, its application as an Intermediate Thermal Hydrolysis Process (ITHP) was studied. The ITHP process configuration consists of a first stage conventional Mesophilic Anaerobic Digestion (MAD) followed by THP and then a second stage MAD (i.e. MAD+THP+MAD). The main aims of this research were therefore to evaluate the impact of the ITHP configuration on an already digested sludge constituents, namely, carbohydrates, proteins and lipids degradation and the extent of their conversion to biogas. The sludge constituents’ degradation as a result of thermal hydrolysis and Anaerobic Digestion (AD) followed a stepwise process where the initial faster degradation was followed by a second stage slower degradation process. The sludge constituents’ degradation kinetic rate constants showed that the use of ITHP can further enhance the already digested sludge degradation reducing the sludge mass and increasing its conversion to biogas. Furthermore, the ITHP configuration showed a significant impact on sludge Extracellular Polymeric Substance (EPS) content. The results obtained from laboratory scale experiments showed that the ITHP process configuration resulted in an overall average VSr of 62% in comparison with the THP configuration which provided a VSr of 47%. As a result, the overall biogas production from the ITHP process was found to be in excess of 478 m3/tonne dry solids (TDS) fed, compared with 345 m3/tds feed from the THP digestion configuration.
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Zheng, Jian. "Effect of mild microwave pretreatment on characteristics and mesophilic digestion of primary sludge." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27314.
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Wastewater treatment produces a large amount of contaminant-containing sewage sludge, disposal of which is of great concern and is tightly regulated. Anaerobic digestion of sewage sludge is used in most large-scale wastewater treatment plants prior to sludge end use or ultimate disposal mainly due to its advantages of low energy consumption and potential energy recovery. Thermal pretreatment has been studied and successfully applied to improve the quality of the digestion product. Microwave (MW) irradiation has become of interest with some advantages over conventional thermal pretreatment. The objective of this research is to investigate whether MW pretreatment can enhance the anaerobic digestion of primary sludge (PS).
The influence of MW irradiation on the characteristics of pretreated primary sludge was studied in terms of MW intensity, sludge solid concentration, and temperature achieved. The experimental range of sludge of sludge characteristics was sludge solid concentration of 1-4% (w/v) total solids (TS), temperature 35-90°C, and MW intensity of 40 and 80%. MW irradiation was found to increase the concentration of soluble COD (SCOD) in the sludge. The ratio of SCOD/TCOD increased from 2.5% to around 6-7% for 4% TS sludge and MW pretreatment temperature of 90°C. Both sludge solid concentration and MW irradiation temperature were shown to be the most important MW pretreatment parameters in solubulizing primary sludge. MW intensity in the range of temperatures studied had no impact on primary sludge solubilization.
Mesophilic biochemical methane potential (BMP) assays were applied to primary sludge pretreated at MW scenarios of 1-4% TS, temperatures 35-90°C, and MW intensity of 40 and 80%. Again, the BMP assay indicated no obvious difference in samples with the same TS concentration and pretreated to similar temperatures but at different MW intensities. Both higher MW pretreatment temperatures and higher TS concentrations significantly improved biogas production rate and reduced required digestion time to achieve 85% of ultimate digestion. For 4% TS primary sludge samples pretreated to 90°C, biogas production rate increased 37% or resulted in a 28% reduction in digestion time to achieve 85% of the ultimate biogas production. There was some indication that MW pretreatment may have caused some very mild inhibition of the whole (soluble and suspended) sludge sample based on the existence of a 2-3 day lag phase for pretreated sludge samples. While MW pretreatment increased the rate of digestion of primary sludge it resulted in no significant increase in the ultimate biogas production and biodegradation of organic matter in terms of VS and TCOD removal. Analysis of biogas production results from the BMP assays indicated that they could be described by a first order reaction. The reaction rate constant increased with increase of TS concentration and MW pretreatment temperature, but was not affected by MW intensity.
BMP assay of the soluble fraction of pretreated primary sludge was carried out on 4% TS primary sludge pretreated at MW intensity of 80% and temperatures of 65°C and 90°C. The soluble fraction was shown to exhibit no methanogenic inhibitory effects.
In general MW pretreatment at the conditions tested did not result in any significant microbial inhibition and resulted in increased rate of primary sludge digestion without increase of the ultimate degradability of the sludge.
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MOURA, Ana Cristine Sandes. "Caracterização da qualidade do leite cru refrigerado produzido em Municípios do Estado de Alagoas, Brasil." Universidade Federal Rural de Pernambuco, 2008. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5120.
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The state of Alagoas is an important producer of milk's derived of the country, but there are few researches about milk's quality, covering their several aspects, targeting the new legislation's requirements. The objective of this study was to assess the chilled raw milk quality in municipalities of this State, in view of, the standards established for the Normative Instruction nº. 51 (IN 51), published in September 18 of 2002 of the Ministry of Agriculture, Livestock and Supplying. In the first stage of the research, held between the months of september and december of 2006, 32 samples of chilled raw milk from eight dairy located in different municipalities of the state of Alagoas were analyzed for counting of somatic cells and determination of fat levels, protein, lactose and total solids and also was verified the existing correlation between them. In the second phase, held between the months of april and august of 2007, 55 samples of chilled raw milk from eleven dairy located in different municipalities of the State previously cited were analyzed for counting of aerobic mesophiles and psychrotrophic and also the determination of the density, cryoscopy and titratable acidity. Among the dairy analyzed, seven (87.5%) presented samples with counting of somatic cells, fat concentration, protein and total solids within the limits required for the legislation. However, one of the dairy analyzed (14.3%) was note that the medium value of somatic cells was finding outside of the default permitted by legislation. Was found a positive correlation (p<0.05) between counting of somatic cells and the fat concentration, while that for protein and total solids such correlation wasn't observed. Of the 55 samples, 35 (63.64%) were outside of the default permitted by legislation for the counting of aerobic mesophiles, seven (12.73%) for the counting of microorganisms psychrotrophic, 14 (25.45%) for the cryoscopy, 11 (20%) for the acidity and five (9.09%) for the density. As to the temperature of collection, there was not influence of it in the microorganisms counting. The analyze of the results found permit say that the majority of the dairy studied meet main requirements on the somatic cells counting, the components and the physicochemical properties of the milk. Meanwhile, about the milk's microbiological aspects, it is accepted that the changes found have their origin associated to the faults in the health management of the herds and the milk's manipulation, including the milking, refrigeration and its transport from farms to the dairy. The effective deployment of the requirements established for IN 51, with the participation of all members of the productive chain of milk, will promote, certainly, the improvement of milk's quality and their derivatives in the Alagoas state, contributing with the good health of the population and increasing the competitiveness of the milk products from this state in other marketplaces.
O estado de Alagoas é um importante produtor de lácteos do País, porém, há poucos estudos sobre a qualidade do leite, abrangendo seus vários aspectos, visando às novas exigências da legislação. Objetivou-se avaliar a qualidade do leite cru refrigerado produzido em municípios deste Estado, tendo em vista os padrões estabelecidos pela Instrução Normativa n 51 (IN 51), publicada em 18 de setembro de 2002 pelo Ministério da Agricultura, Pecuária e Abastecimento. Na primeira etapa da pesquisa, realizada entre os meses de setembro a dezembro de 2006, 32 amostras de leite cru refrigerado, provenientes de oito laticínios localizados em diferentes municípios do estado de Alagoas, foram analisadas para contagem de células somáticas e determinação dos teores de gordura, proteína, lactose e sólidos totais, bem como foi verificada a possibilidade de correlação entre eles. Na segunda etapa da pesquisa, realizada entre os meses de abril a agosto de 2007, 55 amostras de leite cru refrigerado, provenientes de 11 laticínios localizados em diferentes municípios do referido Estado, foram analisadas para a contagem de aeróbios mesófilos e de psicrotróficos, além da determinação da densidade, crioscopia e acidez titulável. Dentre os laticínios analisados, sete (87,5%) apresentaram amostras com contagem de células somáticas, concentração de gordura, proteína e sólidos totais dentro dos limites exigidos pela legislação. Contudo, em um dos laticínios analisados (14,3%), observou-se que o valor médio das células somáticas encontrava-se fora dos padrões permitidos pela legislação. Houve uma correlação positiva (p< 0,05) entre a contagem de células somáticas e a concentração de gordura, enquanto que para proteína e sólidos totais tal correlação não foi observada. Das 55 amostras analisadas, 35 (63,64%) encontravam-se fora dos padrões exigidos pela legislação para contagem de aeróbios mesófilos, sete (12,73%) para contagem de microsganismos psicrotróficos, 14 (25,45%) para a crioscopia, 11 (20%) para a acidez e cinco (9,09%) para a densidade. No que se refere à temperatura de coleta, não houve influência da mesma na contagem de microorganismos. A análise dos resultados obtidos permite afirmar que a maioria dos laticínios estudados atende as principais exigências quanto à contagem de células somáticas, os componentes e as propriedades físico-químicas do leite. Entretanto, no que se refere aos aspectos microbiológicos do leite, admite-se que as alterações observadas tenham sua origem associada à falhas voltadas ao manejo sanitário dos rebanhos e à manipulação do leite, incluindo a ordenha, a refrigeração e o seu transporte das propriedades rurais aos laticínios. A efetiva implantação das exigências estabelecidas pela IN 51, com a participação de todos os integrantes da cadeia produtiva dos lácteos, promoverá, certamente, a melhoria da qualidade do leite e derivados do estado de Alagoas, contribuindo com a boa saúde da população e aumentando a competitividade dos produtos lácteos deste Estado em novos mercados.
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Tavernelli, Ivano. "Protein thermostability : a comparative molecular dynamics investigation on rubredoxins from mesophilic and hyperthermophilic organisms /." [S.l.] : [s.n.], 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13185.
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Masusawa, Chihiro. "Anaerobic processing of baby maize stover for bioenergy production under thermophilic and mesophilic conditions." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/427154/.
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There is a growing consensus that purpose-grown crops should not be used for energy generation, especially if this involves competition for land and resources that could be used for food or animal feed (OECD, 2010). This highlights the need for the use of agricultural or industrial residues as sources of biomass. Tropical Power Ltd opened Africa's first gird-connected anaerobic digestion (AD) plant in Kenya which uses baby maize stover as a substrate. The aim of this work was to assess the digestion of the novel substrate in AD, baby maize stover from Kenya. This research conducted laboratory experiments and modelling, and investigated different approaches (e.g. operating temperatures, pre-treatments and trace elements (TE) supplementation) to improve the overall energy balance and digestion performance of this substrate, in comparison with traditional maize silage as a model for ligno-cellulosic agro-wastes. For laboratory experiments, this work was carried out over 3 hydraulic retention time (HRT) in ten 4 L continuously-stirred tank reactors (CSTR) under thermophilic (55℃) and mesophilic conditions (35℃). The pre-treatment was a thermophilic pre-hydrolysis step before mesophilic digestion. Modelling was conducted by hand calculation and modelling software 'AD assessment tool'. Laboratory experimental data and data from the biogas plant in Kenya were used for the modelling. In laboratory experiments, the greatest methane yield of baby maize stover was found in mesophilic digesters with 5 TE (Fe, Co, Ni, Se, Mo) which was 0.333 L CH4 g-1 volatile solids (VS) at organic loading rate (OLR) 3 g VS L-1 day-1. In contrast, the methane yield in mesophilic digesters with 3 TE (Fe, Co, Ni) was significantly lower than that of thermophilic digesters. 5 TE supplementation helped to provide stable operation and higher methane yield. Even with 5 TE supplementation, however, mesophilic digesters showed signs of failure after 150 days. The volatile fatty acids (VFA) accumulation in thermophilic digesters with 5 TE only fell after W dosing, and it appears W may also help the stable operation. The two-stage system was tested three times under different conditions and the gas production from pre-hydrolysis improved every time; however, specific methane yield in the two-stage system remained less than that of single stage digestion. In modelling, firstly, overall energy balance of the biogas plant in Kenya from 08.2015 to 07.2016 was assessed. The percentage of calculated fuel consumption per actual fuel consumption was 95.3 % so the modelling assumption was close to actual operation. Secondly, rationalisation of the biogas plant design based on actual feedstock availability was conducted because the biogas plant received only 21 % of target feeding and was too large for actual feed availability. This rationalisation was conducted by hand calculation and modelling software AD assessment tool. The required digester volume was 1360 m3 which was 24 % of actual digester volume and less than total volume of 1520 m3 for the hydrolysers in the main plant. While hand calculation considered a more limited range of parameters (energy requirement for heating and energy output as methane) than the AD assessment tool (transportation, heat, CHP, electricity, methane, process loss), both modelling results clearly indicated the net energy output in single-stage mesophilic digestion was greater than that of single-stage thermophilic digestion. When mesophilic digesters fed on baby maize stover at OLR of 3-4 g VS L-1 day-1 received appropriate TE, the specific methane yield was close to that of thermophilic digesters. In terms of overall energy balance, single mesophilic digestion was thus better than single-stage thermophilic digestion and two-stage system for this substrate.
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Stahl, Sarah Elizabeth. "PHOTOOXIDATIVE STRESS RESPONSE IN MESOPHILIC AND PSYCHROPHILIC STRAINS OF CHLAMYDOMONAS RAUDENSIS: A COMPARATIVE STUDY." Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1406916386.
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Thiruvenkadam, Selvakumar. "Evaluation of Cellruptor pre-treatment on biogas yield from various substrates." Thesis, KTH, Skolan för bioteknologi (BIO), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-49144.
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In this thesis work, Cellruptor pre-treatment was evaluated in order to increase biogas yield. Initially, the effects of residence time (30, 60, 90, 120 and 180 min) and substrate release (rapid/non-rapid) from the draining port of Cellruptor on biosludges were investigated to find the optimum operating conditions of Cellruptor. Under these optimum operating conditions, the effect of Cellruptor pre-treatment on batch reactors of various substrates and semi-continuous digester of biosludge were investigated at mesophil biosludge, dewatered sludge, digested sludge, fibre sludge, hay, maize silage, minced meat, orange peel, seaweed and yeast. From the initial study, 90 min residence time and rapid release of pre-treated substrate from draining port were found to be optimum operating conditions of Cellruptor. From the batch experiments, Cellruptor pretreatment showed maximum and minimum increase of methane yield in hay (32%) and dewatered sludge (2%) respectively. The semi-continuous digester experimental results showed increase in biogas production by 22.4% from Cellruptor pre-treatment of biosludge at HRT of 15 days and OLR of 2.0 g VS/L/day. With further studies, Cellruptor pre-treatment may be deployed in large-scale biogas plants to improve biogas yield.
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Huang, Zhanzhao. "Enhanced biogas production by increasing organic load rate in mesophilic anaerobic digestion with sludge recirculation." Thesis, KTH, VA-teknik, Vatten, Avlopp och Avfall, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-99354.
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For enhancing anaerobic sludge digestion and biogas recovery, an increase in organic load rate (OLR) from 1.0 to 3.0kgVS/(m3·day) was imposed upon a new anaerobic digestion process combined with a sludge recirculation. The new setup requires a traditional mesophilic anaerobic digester coupled with a centrifuge for maintaining relatively high solid content within the digester. The hypothesis of this study was that increasing continuously OLR from 1.0 to 3.0kgVS/(m3·day) in a pilot-scale anaerobic digester with recycled sludge would not badly influence the digester stability, based on which biogas production would be enhanced. To test this hypothesis, a continuous 73-day study with laboratory experiment was conducted. Due to scarcity of original feeding sludge and its deteriorating quality, OLR had to be increased relied on introduction of extra sludge followed by measurement of total solid (TS) and volatile solid (VS) contents in both feeding sludge and digester sludge, for calculating OLR and examining its variations. To assess the relationship between biogas production and OLR, a measurement of gas yield and methane content was a necessity, performed by applying a biogas flow meter and MSA AUER EX-METER II (P). Moreover, temperature, pH value, volatile fatty acid (VFA) and alkalinity must be tested frequently, for the purpose of preventing system failure. The results demonstrate that the digester succeeded in withstanding an OLR up to 3.15kgVS/(m3·day). Furthermore, an enhancement in biogas yield and methane content were observed after increasing the OLR by introducing extra sludge. Biogas production measurement performed during this study indicated that biogas yield was enhanced by 73%, with a maximum production of 14.5m3/day, when OLR was increased from 2.05 to 3.15kgVS/(m3·day). However, methane content was merely promoted by 10.5%, to the highest value of 63%, with the same increase in OLR. Specific gas production (SGP), as another means of evaluating the relationship between biogas production and OLR, was observed to be 0.65Nm3/kg VSin averagely.
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Llirós, Dupré Marc. "Diversity, dynamics and activity of mesophilic Archaea in stratified feshwater lakes. Implications in biogeochemical cycles." Doctoral thesis, Universitat de Girona, 2010. http://hdl.handle.net/10803/7641.
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Aquesta tesi doctoral va estudiar la diversitat (riquesa i abundància), la distribució i la dinàmica de les comunitats planctòniques d'Archaea presents a diferents llacs estratificats temperats d'aigua dolça per aportar evidencies sobre la seva distribució i la seva possible activitat en aquests ecosistemes en relació als cicles biogeoquímics presents en els mateixos. Es varen estudiar dos estanyols d'origen càrstic (l'Estanyol del Vilar durant cinc anys consecutius (2001-2005) i l'Estanyol de Can Coromina) i un llac d'origen volcànic (Llac Kivu) analitzant, per una banda, la seva comunitat planctònica d'Archaea mitjançant una aproximació molecular i, per una altra, la seva possible activitat en aquests ambients (p.e., la nitrificació i la fixació de carboni). Per contextualitzar els resultats, es va realitzar un anàlisi in silico dels patrons de distribució global dels Archaea mesòfils mitjançant un anàlisi a nivell de llinatge combinant seqüències del gen 16S rRNA amb diferents eines estadístiques i d'ecologia general.The present PhD thesis analysed the diversity (richness and evenness), distribution and dynamics of planktonic Archaea in several temperate stratified freshwater lakes to shed some light on their distribution and potential activity in these ecosystems in relation to prevalent biogeochemical cycles. In this sense, two karstic lagoons (Lake Vilar during five consecutive years (2001-2005) and Coromina lagoon) and a volcanic lake (Lake Kivu) were studied analysing, in the one hand, their archaeal planktonic community throughout a molecular approach and, in the other hand, their potential acitivity in these environments (e.g., nitrification and carbon fixation). In order to contextualize the obtained results, an in silico phylogenetic lineage-based analysis on the global distribution of lacustrine Archaea was conducted using 16S rRNA gene sequences in combination with statistical and general ecology tools.
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Landre, Julien B. P. "Investigation of mesophilic Aeromonas : response to hydrogen peroxide and role in false-positive Colilert reaction." Thesis, Robert Gordon University, 1999. http://hdl.handle.net/10059/532.
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Mesophilic Aeromonas are opportunistic human pathogens which produce a wide range of virulence factors and have been isolated from both untreated and chlorinated drinking waters. The presence of these microorganisms in the distribution systems suggests that Aeromonas could display an adaptive response to oxidant present during water treatment. This adaptive response of Aeromonas would lead to interference in analysis for faecal coliforms used to determine the quality of potable drinking water, and be a potential source of intestinal disorders. The Colilert defmed substrate technology system was developed as a one-step detection of both coliforms and E. coli while suppressing non-coliform heterotrophic growth. Aeromonas species were previously shown to cause production of falsepositive reaction at high cell densities (Edberg et ai., 1988). Similar results were obtained in our study when using fresh Colilert reagents. However, results obtained during this project showed Aeromonas to mediate false-positive reactions at low cell densities (101 cells/ml in presence of salt, 102 cells/ml in absence of salt) when using Colilert reagents within 4 weeks prior to shelf-life expiry. Increased incidence in falsepositive reactions mediated by Aeromonas were shown to be dependent upon the stability of the Colilert reagent affected with age. Such Aeromonas interference would lead to over-estimation of coliforms and E. coli in potable drinking water supplies. The ability of bacteria to adapt to a wide range of stress factors such as pH, heat shock, oxidants or starvation has been extensively studied. Little is known about the response of Aeromonas to such stress conditions. During this project, it has been demonstrated that mesophilic Aeromonas display an adaptive tolerance response to a lethal oxidative challenge through pre-treatment with a sub-lethal dose of oxidant. The stress adaptation process was demonstrated to occur through synthesis of stress proteins and modulation of pre-existing catalase. Of the species studied, A. sobria was most sensitive, whereas A. caviae and A. hydrophila displayed similar responses to oxidative stress. The hypersensitivity of A. sobria did not impair the adaptive response of the organism. During our investigations, stationary phase Aeromonas cells have been shown to be more resistant than their logarithmic counterpart and suggested that excreted molecules may playa role in protecting the cells. Re-suspension of fresh cells into spent medium from a stationary phase cells revealed a higher resistance of these cells compared to those re-suspended in minimal medium. This resistance was demonstrated to be mediated by non-proteinaceous, thermo-sensitive effector molecule. A potential candidate as the effector molecule, butyryl homo serine lactone, was synthesised and assayed. Preliminary data strongly suggest that this molecule has a role to play in the stress adaptation phenomenon and might be involved in stimulating synthesis of key stress proteins.
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MBARGA, BINDZI MARIE-ALAIN. "Processus de reconstitution de la foret dense mesophile guineenne : cas du secteur forestier de la region de yaounde (cameroun)." Paris 11, 1992. http://www.theses.fr/1992PA112346.
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Cette etude concerne l'evolution de la composition floristique et de la structure des communautes vegetales apres la deprise agricole dans le secteur de la foret mesophile du cameroun. En outre, elle tente d'apprecier les modalites qui accompagnent la reconstitution du couvert forestier et de retracer les differentes etapes de la remontee biologique dans ce secteur. Apres un rappel des caracteres generaux du territoire et de la zone d'etude qui est prise en sandwich entre deux entites phytogeographiques distinctes (secteur de la foret dense ombrophile et secteur des savanes periforestieres), l'etude de la reconstitution du couvert forestier est realisee par approche synchronique. La discrimination des communautes vegetales par la methode phytosociologique faisant appel aux techniques numeriques (afc, cah, etc) a permis la mise en evidence de dix-sept groupements, apparentes a sept types de vegetation ayant valeur d'alliance, dont le determinisme est essentiellement edaphique et chronologique. L'aspect structural des communautes discriminees est etudie sous l'angle de la repartition des individus et des types biophysionomiques dans le plan vertical. Les rythmes de changement des parametres structurels et fonctionnels sont egalement abordes et un schema syndynamique de la vegetation postculturale est propose. Les resultats obtenus montrent un emboitement des stades floristiques le long de la chronosequence, en raison de la presence d'un lot impressionnant d'especes compagnes. La composition floristique montre des variations importantes liees a la fois aux facteurs introduits ou preexistants dans le milieu et a l'age d'abandon des parcelles. En general, la richesse et la diversite specifiques sont plus elevees aux stades intermediaires et preclimaciques, stades correspondant a la presence simultanee de plusieurs strates. La syndynamique de cette vegetation demeure essentiellement sous l'influence des activites humaines, cependant elle montre des potentialites d'un retour rapide vers le stade climacique