Este estudo investigou a aplicação de um reator anaeróbio operado em bateladas sequenciais com biomassa imobilizada (AnSBBR) com agitação na produção de biohidrogênio tratando água residuária sintética a base de sacarose, sendo o desempenho do biorreator avaliado de acordo com a influência conjunta do tempo de alimentação, do tempo de ciclo, da concentração afluente e da carga orgânica volumétrica aplicada (COVAS). O biorreator, com capacidade útil de 5,6 L, foi dividido em 3 partes: volume de meio tratado por ciclo de 1,5 L, volume residual de meio de 2,0 L e volume de suporte inerte com biomassa de 2,1 L. Foram aplicadas 6 condições experimentais de COVAS de 9,0 a 27,0 gDQO.L-1.d-1, combinado diferentes concentrações afluentes (3500 e 5400 mgDQO.L-1), tempos de ciclo (4, 3 e 2h), sendo tempo de enchimento do reator (tC) correspondente a 50% ao tempo de ciclo. Os resultados mostraram que o aumento COVAS contribuiu para a queda no consumo de sacarose de 99% para 86% e para o aumento do rendimento molar por carga removida (RMCRC,n) de 1,02 molH2.molSAC-1 na COVAS de 9,0 gDQO.L-1.d-1 até atingir o valor máximo de 1,48 molH2.molSAC-1 na COVAS de 18,0 gDQO.L-1.d-1 com queda a partir desse ponto. O aumento da COVAS resultou no aumento da produtividade molar volumétrica (PrM) de 24,5 para 81,2 molH2.m-3.d-1. A maior produtividade molar específica (PrME) obtida foi de 8,71 molH2.kgSVT-1.d-1 para a COVAS de 18,0 gDQO.L-1.d-1. A diminuição do tempo de ciclo resultou na diminuição do consumo de sacarose e no aumento da PrM. Foi verificado também que a diminuição do tC de 4h para 3h contribuiu para o aumento da PrME. O aumento da concentração afluente resultou na diminuição do consumo de sacarose apenas na faixa de 2h, no aumento do RMCRC,n e da PrM em todas as faixas de tC, e no aumento da PrME nas faixas de 4h e 3h. A estratégia de alimentação mostrou ser um parâmetro operacional de grande importância, sendo o aumento do tempo de enchimento responsável pelo aumento do consumo de sacarose, da PrM, da PrME e do RMCRC,n para todas as COAVS investigadas. Em todas as condições, houve o predomínio do ácido acético seguido pelo etanol, ácido butírico e propiônico. / This study investigated the feasibility of an anaerobic sequencing batch biofilm reactor (AnSBBR) with agitation on biohydrogen production treating synthetic wastewater from sucrose, the performance of the bioreactor was evaluated according the combined influence of fill time, cycle period, influent concentration and applied organic loading rate (COAVS) . The bioreactor, with working volume of 5,6L, was divided in 3 parts: 1,5L of fed volume per cycle, 2,0L of residual medium and 2,1L of inert support and biomass. The reactor was operated under six operating conditions with different COAVS ranging from 9,0 to 27,0 gCOD.L-1.d-1, obtained by the combination of different influent concentrations (3500 e 5400 mgCOD.L-1), cycle periods (4, 3 e 2h) and fill time corresponding to 50% of cycle period. The results showed that increasing COAVS resulted in lesser sucrose removal from 99% to 86% and improved yield per removed loading rate (RMCRC,n) of 1,02 molH2.molSUC-1 in COAVS of 9,0 gCOD.L-1.d-1 to maximum value of 1,48 molH2.molSUC-1 in COAVS of 18,0 gCOD.L-1.d-1 decreasing after that. Increasing COAVS improved molar productivity (PrM) from 24,5 to 81,2 molH2.m-3.d-1. The higher specific molar productivity (PrME) obtained was 8,71 molH2.kgTVS-1.d-1 in COAVS of 18,0 gCOD.L-1.d-1. Decreasing cycle period resulted in less sucrose consumption and increased PrM. It was observed that decreasing cycle period of 4h to 3h improved PrME. Increasing influent concentration resulted in less sucrose degradation only on range of 2h, in an increase of RMCRC,n and in an increase of PrM in all ranges of tC, and increased PrME on ranges of 4h and 3h. In all operational conditions, the main intermediate metabolic was acetic acid followed by ethanol, butyric and propionic acids. The feeding strategy had a great effective on hydrogen production, longer fill times resulted in better sucrose removal, PrM, PrME and RMCRC,n for all COAVS investigated.

O aproveitamento da energia luminosa por bactérias que produzem hidrogenases poderia aumentar a eficiência do processo de produção de biohidrogênio. Neste trabalho, foi realizada a clonagem do gene que codifica a proteorrodopsina (PR) do isolado metagenômico SAR86 num plasmídeo de expressão para bactérias Gram-negativas. PR é uma proteína ligada ao cromóforo retinal, que, sob iluminação, promove o efluxo de prótons através da membrana celular. O excesso de prótons na face externa da membrana pode servir como substrato para a hidrogenase, resultando em maior eficiência na produção de hidrogênio (2H+ + 2e→ H2). O plasmídeo contendo o gene da PR foi utilizado na transformação genética das bactérias Cupriavidus necator e Escherichia coli, que produzem diversas hidrogenases. Enquanto a PR não se mostrou funcional em C. necator, na linhagem recombinante de E. coli, cultivada em presença de luz e retinal, foi obtido um aumento de até 2,17 vezes na produção de H2 em relação ao cultivo no escuro, desde que a linhagem estivesse produzindo a hidrogenase endógena HYD-4. / The utilization of light energy by hydrogenase producing bacteria could increase the efficiency of the biohydrogen production process. In the present work, the gene coding for proteorhodopsin (PR) of the SAR86 metagenomic lineage was cloned in an expression plasmid for Gram-negative bacteria. PR is an apoprotein linked to the chromophore retinal, which, upon illumination, promotes proton efflux across the cell membrane. The excess of protons on the plasma membrane surface may serve as a substrate for hydrogenases, resulting in a higher efficiency of hydrogen production (2H+ + 2e→ H2). The plasmid containing the PR gene was used to transform the Gram-negative bacteria Cupriavidus necator and Escherichia coli which produce several hydrogenases. Whereas PR did not display functionality in C. necator, in the recombinant E. coli cells, grown under illumination in the presence of retinal, an enhancement up to 2.17 fold in H2 production was found, relative to cells grown under darkness, provided that the cells were expressing the endogenous HYD-4 hydrogenase.

Este estudo investigou a aplicação de um AnSBBR com recirculação da fase líquida tratando água residuária a base de glicerina (efluente do processo de produção de biodiesel) para a produção de biohidrogênio, sendo o desempenho do biorreator avaliado de acordo com a influência conjunta do tempo de alimentação, do tempo de ciclo e da concentração afluente. O biorreator teve um volume de meio tratado por ciclo de 1,5 L, volume residual de meio de 2,0 L e volume de suporte inerte com biomassa de 2,1 L, sendo mantido a 30°C durante todo o estudo. O trabalho foi divido em três fases: a Fase I foi realizada para determinar os melhores parâmetros de operação do reator (tipo de inóculo, tipo de glicerina, tipo de suporte, concentração de NaHCO3 e velocidade ascensional) para dar seguimento com a Fase II que estudou apenas o efeito da concentração do afluente, tempo de ciclo e tempo de enchimento. Os parâmetros utilizados na Fase II foram: lodo de abatedouro de aves pré-tratado por HST (Heat Shock Treatment 90°C por 10 minutos) como inóculo, glicerina pura comercial para eliminar interferência de possíveis resíduos, suporte de PEBD (polietileno de baixa densidade) e 100 mg.L-1 de NaHCO3. Na Fase II, foram aplicadas 6 condições experimentais com cargas orgânica volumétrica (COVAS) de 7,7 a 17,1 gDQO.L-1.d-1, combinando diferentes concentrações afluentes (3000, 4000 e 5000 mgDQO.L-1) e tempos de ciclo (4 e 3 h), sendo o tempo de alimentação igual a metade do tempo de ciclo. Os resultados mostraram que houve baixa remoção de DQO (máximo de 38% para amostras filtradas) e que houve predomínio do ácido acético e do ácido butírico em todas as condições. O aumento da XV concentração do afluente e a diminuição do tempo de ciclo favoreceram a produtividade e rendimento molares de hidrogênio nas condições investigadas. O ensaio com melhores resultados foi com carga orgânica de 17,1 gDQO.L-1.d-1 no qual obteve-se 100,8 molH2.m-3.d-1 e 20,0 molH2.kgDQO-1, com 68% de H2 e apenas 3% de CH4 no biogás. Na Fase III, determinou-se a influência do pré-tratamento do inóculo e a viabilidade do sistema tratando glicerina bruta industrial, sendo verificado que o pré-tratamento do lodo por HST melhora ligeiramente a produtividade e rendimento do processo e o uso da glicerina bruta industrial diminuiu consideravelmente a quantidade e qualidade do biogás obtido. / This study investigated the feasibility of an AnSBBR with recirculation of the liquid phase treating glycerin-based wastewater (effluent from biodiesel production process) on biohydrogen production; the performance of the bioreactor was evaluated according the combined influence of fill time, cycle period and influent concentration. The bioreactor had 1.5L of feeding volume per cycle, 2.0 L of residual medium, 2.1 L of inert support and biomass and it was kept at 30°C. This study was divided into three phases. Phase I was conducted to determine the best operational parameters for the reactor (type of inoculum, type of glycerin, type of support for biomass, NaHCO3 concentration and upflow velocity), so Phase II would use these parameters to study only the influence of affluent concentration, cycle time and filling time. The parameters used in Phase II were: sludge from poultry slaughterhouse pretreated by HST (Heat Shock Treatment 90°C for 10 minutes) as inoculum, pure glycerin so there would be no interferences from possible residues, LDPE (low density polyethylene) support, 100 mg.L-1 of NaHCO3 and 10.6 m.h-1 of upflow velocity. Phase II was operated under six conditions with different AOLRS ranging from 7.7 to 17.1 gCOD.L-1.d-1, obtained by the combination of different influent concentrations (3000, 4000 and 5000 mgCOD.L-1) and cycle periods (4 and 3 h), the filling time was equal to half of the cycle lenght. The results showed low COD removal (maximum of 38% for filtrated samples) and high concentrations of acetic acid and butyric acid in all conditions. Increasing the affluent concentration and decreasing the cycle length improved the molar productivy and hydrogen yield in the XVII investigated conditions. The condition with better results was the one operated with 17.1 gCOD.L-1.d-1 of AVOL, it reached 100.8 molH2.m-3.d-1 and 20.0 molH2.kgCOD-1, with 68% of H2 and only 3% of CH4 in its biogas. Phase III determined whether there is a real influence on the pretreatment of the sludge and the feasibility of this system treating industrial glycerin, the results show that the pretreatment of the sludge by HST slightly improves the productivity and the process yield and the wastewater made from industrial glycerin substantially decreased the quantity and the quality of the biogas generated.

No description available.

Submitted by Regina Francielle Silva Paulino null (repaulino28@yahoo.com.br) on 2017-05-15T16:55:58Z No. of bitstreams: 1 Disssertação para repositório.pdf: 2094038 bytes, checksum: 627da6791c7083908510f6129d80d56f (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-05-16T14:35:09Z (GMT) No. of bitstreams: 1 paulino_rfs_me_guara.pdf: 2094038 bytes, checksum: 627da6791c7083908510f6129d80d56f (MD5) / Made available in DSpace on 2017-05-16T14:35:09Z (GMT). No. of bitstreams: 1 paulino_rfs_me_guara.pdf: 2094038 bytes, checksum: 627da6791c7083908510f6129d80d56f (MD5) Previous issue date: 2017-03-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho são estudados dois processos que utilizam biogás para obtenção do biohidrogênio. Inicialmente é analisado o processo de eletrólise da água, com o uso de energia elétrica gerada em conjunto motor de combustão interna/gerador (MCI) operando com biogás de aterro sanitário. Visando aproveitamento de calor dos gases de escape do MCI estuda-se o potencial de geração de energia térmica útil pela aplicação da técnica de cogeração. Considera-se dois casos: o primeiro para a produção de água quente em um trocador de calor, e o segundo, para a produção de água gelada em um sistema de refrigeração por absorção. Posteriormente é estudada a reforma a vapor de biogás para a produção de biohidrogênio, que utiliza também esse biocombustível para a geração de vapor superaquecido necessário ao processo de reforma. O objetivo é efetuar a análise energética de modo a determinar as eficiências dos processos, o potencial de produção de biohidrogênio, água quente ou água gelada, nos aterros sanitários da cidade de São Paulo. Também é efetuada análise de engenharia econômica para a determinação do custos da produção de biohidrogênio, água quente e água gelada, em US$/kWh. Esse estudo baseia-se em parâmetros tais como, investimento capital, custos de manutenção e operação dos equipamentos, período equivalente de utilização e período de amortização de capital. Em fase final, foram realizados estudos de impactos ambientais para a determinação das eficiências ecológicas dos processos de produção de biohidrogênio (reforma a vapor e eletrólise), considerando as emissões de poluentes, o dióxido de carbono equivalente e os indicadores de poluição. Como conclusões, tem-se que considerando a disponibilidade de biogás da cidade de São Paulo, existe potencial para a produção de biohidrogênio, e que o processo de reforma a vapor do biogás apresenta maior nível de eficiência sob o ponto de vista termodinâmico. Quando se considera a eletrólise incorporando a técnica da cogeração com a produção simultânea de eletricidade e água quente ou água gelada, observa-se aumento da eficiência energética do processo. A reforma a vapor do biogás, também se mostra mais atrativa economicamente de acordo com os parâmetros considerados. Sobre o ponto de vista ambiental, o processo de eletrólise com produção de água gelada apresenta maior eficiência ecológica, seguidos do processo de produção de água quente, reforma a vapor e somente eletrólise. / In this work is studied two processes to obtain hydrogen using biogas. Initially is analyzed the process of electrolysis of water, with the use of electricity generated in conjunction with an internal combustion engine / generator (ICE) operating with landfill biogas. generated by an internal combustion engine/generator operating with landfill biogas, is analyzed. In order to take advantage of the exhaust gases from the combustion of biogas, the potential of cogeneration is studied, another two cases are considered. The first one studies the production of hot water in the heat exchanger and the second analyzes the use of absorption refrigeration system to produce cold water. Subsequently it is studied the steam reform of biogas for the production of hydrogen, which is constituted of biogas burning for the generation of superheated steam used in the conversion of the fuel input. The objective is to make the energy analysis in order to determine the efficiency of the processes and the potential of producing hydrogen, hot water or ice water in the landfills of the city of São Paulo using the biogas generated. An economic engineering analysis to determine the production hydrogen cost, hot water and ice water, in US$/kWh, based on capital investment, maintenance and operation costs, equivalent period of use and payback. In the final phase, environmental study method is applied to determine the ecological efficiencies of the hydrogen production processes using biogas, considering the emissions of pollutants, carbon dioxide equivalent and pollution indicator. As a conclusion, considering the hydrogen production capacity and the biogas availability of the city of São Paulo, the process of steam reforming of the biogas is more thermodynamically efficient. When considering the electrolysis incorporating the cogeneration technique with the simultaneous production of electricity and hot water or cold water, it is observed an increase in the energy efficiency of the process. The steam reform of the biogas is more attractive economically according to the considered parameters. From the environmental point of view, the process of electrolysis with the production of cold water presents greater ecological efficiency, followed by the process of hot water production, steam reforming and only electrolysis.

Este estudo investigou a aplicação de um AnSBBR com recirculação da fase líquida tratando água residuária a base de glicerina (efluente do processo de produção de biodiesel) para a produção de biohidrogênio, sendo o desempenho do biorreator avaliado de acordo com a influência conjunta do tempo de alimentação, do tempo de ciclo e da concentração afluente. O biorreator teve um volume de meio tratado por ciclo de 1,5 L, volume residual de meio de 2,0 L e volume de suporte inerte com biomassa de 2,1 L, sendo mantido a 30°C durante todo o estudo. O trabalho foi divido em três fases: a Fase I foi realizada para determinar os melhores parâmetros de operação do reator (tipo de inóculo, tipo de glicerina, tipo de suporte, concentração de NaHCO3 e velocidade ascensional) para dar seguimento com a Fase II que estudou apenas o efeito da concentração do afluente, tempo de ciclo e tempo de enchimento. Os parâmetros utilizados na Fase II foram: lodo de abatedouro de aves pré-tratado por HST (Heat Shock Treatment 90°C por 10 minutos) como inóculo, glicerina pura comercial para eliminar interferência de possíveis resíduos, suporte de PEBD (polietileno de baixa densidade) e 100 mg.L-1 de NaHCO3. Na Fase II, foram aplicadas 6 condições experimentais com cargas orgânica volumétrica (COVAS) de 7,7 a 17,1 gDQO.L-1.d-1, combinando diferentes concentrações afluentes (3000, 4000 e 5000 mgDQO.L-1) e tempos de ciclo (4 e 3 h), sendo o tempo de alimentação igual a metade do tempo de ciclo. Os resultados mostraram que houve baixa remoção de DQO (máximo de 38% para amostras filtradas) e que houve predomínio do ácido acético e do ácido butírico em todas as condições. O aumento da XV concentração do afluente e a diminuição do tempo de ciclo favoreceram a produtividade e rendimento molares de hidrogênio nas condições investigadas. O ensaio com melhores resultados foi com carga orgânica de 17,1 gDQO.L-1.d-1 no qual obteve-se 100,8 molH2.m-3.d-1 e 20,0 molH2.kgDQO-1, com 68% de H2 e apenas 3% de CH4 no biogás. Na Fase III, determinou-se a influência do pré-tratamento do inóculo e a viabilidade do sistema tratando glicerina bruta industrial, sendo verificado que o pré-tratamento do lodo por HST melhora ligeiramente a produtividade e rendimento do processo e o uso da glicerina bruta industrial diminuiu consideravelmente a quantidade e qualidade do biogás obtido. / This study investigated the feasibility of an AnSBBR with recirculation of the liquid phase treating glycerin-based wastewater (effluent from biodiesel production process) on biohydrogen production; the performance of the bioreactor was evaluated according the combined influence of fill time, cycle period and influent concentration. The bioreactor had 1.5L of feeding volume per cycle, 2.0 L of residual medium, 2.1 L of inert support and biomass and it was kept at 30°C. This study was divided into three phases. Phase I was conducted to determine the best operational parameters for the reactor (type of inoculum, type of glycerin, type of support for biomass, NaHCO3 concentration and upflow velocity), so Phase II would use these parameters to study only the influence of affluent concentration, cycle time and filling time. The parameters used in Phase II were: sludge from poultry slaughterhouse pretreated by HST (Heat Shock Treatment 90°C for 10 minutes) as inoculum, pure glycerin so there would be no interferences from possible residues, LDPE (low density polyethylene) support, 100 mg.L-1 of NaHCO3 and 10.6 m.h-1 of upflow velocity. Phase II was operated under six conditions with different AOLRS ranging from 7.7 to 17.1 gCOD.L-1.d-1, obtained by the combination of different influent concentrations (3000, 4000 and 5000 mgCOD.L-1) and cycle periods (4 and 3 h), the filling time was equal to half of the cycle lenght. The results showed low COD removal (maximum of 38% for filtrated samples) and high concentrations of acetic acid and butyric acid in all conditions. Increasing the affluent concentration and decreasing the cycle length improved the molar productivy and hydrogen yield in the XVII investigated conditions. The condition with better results was the one operated with 17.1 gCOD.L-1.d-1 of AVOL, it reached 100.8 molH2.m-3.d-1 and 20.0 molH2.kgCOD-1, with 68% of H2 and only 3% of CH4 in its biogas. Phase III determined whether there is a real influence on the pretreatment of the sludge and the feasibility of this system treating industrial glycerin, the results show that the pretreatment of the sludge by HST slightly improves the productivity and the process yield and the wastewater made from industrial glycerin substantially decreased the quantity and the quality of the biogas generated.

Ce travail porte sur la destruction quantitative et d'une manière respectueuse pour l'environnement de solutions concentrées en nitrates par deux procédés différents. Dans les deux cas, la solution de nitrates est d'abord réduite électrochimiquement en ammoniums sur électrode de cuivre avec une sélectivité élevée, ceci quel que soit le pH de la solution d'électrolyse. Dans le premier procédé, l'ammonium est ensuite oxydé en azote à l'aide d'ions hypochlorites générés électrochimiquement. Une excellente sélectivité réactionnelle en azote de 91,5% est obtenue avec des rendements chimiques et faradiques élevés pour la réaction de réduction des nitrates en azote, accompagnée d'une consommation énergétique basse. Le deuxième procédé est un couplage électrochimique / biologique où les solutions d'ammonium seront utilisées comme substrat azoté pour produire du biohydrogène via des boues traitées thermiquement. Une consommation complète de la solution d'ammonium provenant de la réduction des nitrates est obtenue. Un rendement maximal de 0,35 mole H2/mole de glucose est atteint en utilisant des boues activées collectées d'un bassin d'aération contre 1,1 mole H2/mole de glucose produit dans le cas des boues prélevées d'un digesteur anaérobie. / This work deals with the quantitative and environmentally friendly destruction of concentrated nitrates solutions using two different processes. In both cases, the nitrates solution was firstly reduced electrochemically into ammonium on a porous copper electrode. Whatever the initial pH of the electrolytic solution, a high ammonium selectivity was obtained. In the first process, the ammonium was subsequently oxidized to nitrogen gas by hypochlorite ions generated electrochemically. An excellent selectivity of 91.5% with high current efficiency and high chemical yield toward the nitrogen formation was recorded, with a low power consumption. The second method is an electrochemical / biological coupling process where the obtained ammonium solution will be used as a nitrogen source to produce biohydrogen (H2) via heat-treated sludge cultures. A complete assimilation of the ammonium solution resulting from the electroreduction of nitrate was obtained. A maximum hydrogen yield of 0.35 mol H2/mole glucose was achieved using activated sludge collected from an aeration tank versus 1.1 mole H2/mole glucose produced in the case of sludge taken from an anaerobic digester.

<p>Molecular hydrogen is a potential energy carrier for the future. Nitrogen-fixing cyanobacteria are a group of photosynthetic microorganisms with the inherent ability to produce molecular hydrogen via the enzyme complex nitrogenase. This hydrogen is not released, however, but is recaptured by the bacteria using an uptake hydrogenase. In this thesis, genes involved in cyanobacterial hydrogen metabolism were examined, and the possibility of employing genetically modified cyanobacteria for hydrogen production was investigated.</p><p><i>Nostoc punctiforme</i> PCC 73102 (ATCC 29133) is a nitrogen-fixing filamentous cyanobacterium containing an uptake hydrogenase encoded by <i>hupSL</i>. The transcription of <i>hupSL</i> was characterised, and putative regulatory elements in the region upstream of the transcription start site were identified. One of these, a binding motif for the global nitrogen regulator NtcA, was further investigated by mobility shift assays, and it was found that the motif is functional in binding NtcA. Also, a set of genes involved in maturation of hydrogenases was identified in <i>N. punctiforme</i>, the <i>hypFCDEAB</i> operon. These genes were found to be situated upstream of <i>hupSL</i> in the opposite direction, and they were preceded by a previously unknown open reading frame, that was found to be transcribed as part of the same operon.</p><p>The potential for hydrogen production by filamentous cyanobacteria was investigated by studying mutant strains lacking an uptake hydrogenase. A mutant strain of <i>N. punctiforme</i> was constructed, where <i>hupL</i> was inactivated. It was found that cultures of this strain evolve hydrogen during nitrogen fixation. Gas exchange in the <i>hupL</i>^- mutant and in wild type <i>N. punctiforme</i> was measured using a mass spectrometer, and conditions under which hydrogen production from the nitrogenase could be increased at the expense of nitrogen fixation were identified. Growth and hydrogen production in continuous cultures of a Hup^- mutant of the related strain <i>Nostoc</i> PCC 7120 were also studied. </p><p>This thesis advances the knowledge about cyanobacterial hydrogen metabolism and opens possibilities for further development of a process for hydrogen production using filamentous cyanobacteria.</p>

Molecular hydrogen is a potential energy carrier for the future. Nitrogen-fixing cyanobacteria are a group of photosynthetic microorganisms with the inherent ability to produce molecular hydrogen via the enzyme complex nitrogenase. This hydrogen is not released, however, but is recaptured by the bacteria using an uptake hydrogenase. In this thesis, genes involved in cyanobacterial hydrogen metabolism were examined, and the possibility of employing genetically modified cyanobacteria for hydrogen production was investigated. Nostoc punctiforme PCC 73102 (ATCC 29133) is a nitrogen-fixing filamentous cyanobacterium containing an uptake hydrogenase encoded by hupSL. The transcription of hupSL was characterised, and putative regulatory elements in the region upstream of the transcription start site were identified. One of these, a binding motif for the global nitrogen regulator NtcA, was further investigated by mobility shift assays, and it was found that the motif is functional in binding NtcA. Also, a set of genes involved in maturation of hydrogenases was identified in N. punctiforme, the hypFCDEAB operon. These genes were found to be situated upstream of hupSL in the opposite direction, and they were preceded by a previously unknown open reading frame, that was found to be transcribed as part of the same operon. The potential for hydrogen production by filamentous cyanobacteria was investigated by studying mutant strains lacking an uptake hydrogenase. A mutant strain of N. punctiforme was constructed, where hupL was inactivated. It was found that cultures of this strain evolve hydrogen during nitrogen fixation. Gas exchange in the hupL- mutant and in wild type N. punctiforme was measured using a mass spectrometer, and conditions under which hydrogen production from the nitrogenase could be increased at the expense of nitrogen fixation were identified. Growth and hydrogen production in continuous cultures of a Hup- mutant of the related strain Nostoc PCC 7120 were also studied. This thesis advances the knowledge about cyanobacterial hydrogen metabolism and opens possibilities for further development of a process for hydrogen production using filamentous cyanobacteria.

Sverige har som mål att bli helt fossilfri till år 2045. Energymyndigheten har därför tagit fram ett förslag till Vätgasstrategi för att ställa om vätgasproduktionen till att vara helt fossilfri till 2045. Idag används ca 180 000 ton vätgas, vilket motsvarar ett energiinnehåll på ca 6 TWh. Termo-kemisk omvandling av fossila bränslen står för 67% av Sveriges vätgasproduktion, medan 30% är biprodukter från industriella processer och 3% produceras med elektrolysörer. Att ersätta all fossil vätgas med elektrolysör-baserad vätgas innebär en elförbrukning motsvarande 60-126 TWh/år, vilket är en ökning på 40-80% jämfört med de 159 TWh el producerade i Sverige 2020. Energimyndigheten bedömer att vätgas har en viktig roll i att lyckas göra Sverige fossilfritt, delvis genom att den ska kunna fungera som energibärare eller energilagring för att jämna ut variationer i produktion hos förnybara energikällor. Av den anledningen kommer antagligen behovet av vätgas öka, och därmed även energibehovet för att producera vätgas öka ännu mer än 60-126 TWh/år om den fossila vätgasen ska bli ersatt med endast elektrolysör-baserad vätgas. Med tanke på begränsningar i expansion av förnybar elproduktion, kommer behovet av vätgas antagligen inte kunna täckas av endast elektrolysör-baserad vätgas. Därför bör möjligheterna för att även satsa på bio-vätgas, där vätgas produceras av antingen bakterier eller genom refinery av biobaserade råvaror, undersökas. Detta examensarbete ska undersöka möjligheter för vätgasproduktion i Sverige och jämföra olika produktionteknikers förutsättningar. En hypotes är att en hållbar strategi är att kombinera elektrolysör-baserad vätgas med bio-vätgas för att få en diversifierad produktion. Att ha olika produktionsmetoder som komplementerar varandra ger en mer stabil och säker produktion, eftersom de kommer påverkas olika av förändringar i produktionsförutsättningar i samhället. Detta arbete söker svara på följande frågor: Vilka tekniker finns tillgängliga för industriell/kommersiell produktion, var borde R&amp;D riktas för de tekniker som inte är redo för kommersiell produktion, vilket Carbon Footprint (CF) har de olika teknikerna, en uppskattad produktionskostnad för de olika teknikerna, och vilken tillgänglighet för de olika råvarorna finns i Sverige? / Sweden has a goal to be completely fossil-free by 2045. Accordingly, the government has published a suggested Hydrogen Strategy to have made all hydrogen production in Sweden fossil-free by 2045. The Swedish hydrogen use is 180,000 ton, equaling an energy content of 6 TWh/year. Thermo-chemical conversion of fossil fuels accounts for 67% of Swedens hydrogen production, while 30% is byproducts from industry and 3% is electrolysis production. To replace all fossil hydrogen with electrolysis production, would give an increase of electrical demand with 60-126 TWh/year, or 40-80% increase compared to the 159 TWh electricity produced during 2020 in Sweden. Furtherly, the Ministry of Energy deem hydrogen to be key in the general transformation of Sweden to become fossil-free, with one reason being that hydrogen can be used as energy carrier to even out the variations in electricity production that renewable energy has. The need of hydrogen will therefore most likely increase until 2045, thus the electric energy demand for hydrogen production will increase as well, if it would be replaced solely with production using electrolysis. Given the constraints to the capacity of electricity production from renewable sources alone in Sweden, the electricity demand for hydrogen cannot be met by the electricity production. Thus, the possible role of biohydrogen, where hydrogen is produced using biorefinery or microbial production, should be investigated. This master thesis project will investigate the feasibility of hydrogen production in Sweden and compare different options for hydrogen production. A hypothesis of the project is that the most sustainable strategy for hydrogen production in Sweden will be with a diversified portfolio of production designs. Both biohydrogen and electrolysis hydrogen from renewable energy will complement each other in the future. By doing so, the energy sector will be more sustainable and stable since the techniques do not react alike to change in production conditions. The report aims to answer: What techniques are available for industrial production, where should R&amp;D be directed for techniques not ready for industry, what is the estimated carbon footprint (CF) of the industrially available techniques, what is the estimated production cost for each technique, what availability is there in Sweden for the feedstock needed for each technique?