Avec 67 Mt de fumiers de bovins récupérés chaque année, la France possède un gisement considérable de substrats agricoles mobilisables et valorisables par méthanisation. Le procédé de méthanisation par voie sèche, discontinu, avec recirculation de lixiviat semble être le mieux adapté à la valorisation de ce type de substrats à forte teneur en matière sèche (>20%). A l’heure actuelle, ce procédé est cependant rare sur le territoire. Afin de permettre et de pérenniser le développement de cette technologie, des verrous techniques et scientifiques doivent être levés, notamment ceux qui portent sur la recirculation des lixiviats. L’objectif de cette thèse est d’optimiser le procédé de méthanisation par voie sèche appliquée aux effluents agricoles (principalement fumiers de bovins), afin d’atteindre les conditions les plus favorables à la production d’un maximum de biogaz, de façon constante et en un minimum de temps en considérant les contraintes relatives à un tel procédé. Dans un premier temps, l’objectif a été de comprendre le rôle du lixiviat dans ce procédé de digestion anaérobie discontinu, d’un point de vue biologique. Pour se faire quatre lixiviats ayant différentes origines ont été utilisés. Deux d’entre eux étaient biologiquement actifs (lixiviats provenant de méthaniseurs) et les deux autres stérilisés. Du point de vue abiotique, il a été montré que pour favoriser la digestion anaérobie, le lixiviat devait avoir un pH adéquat, présenter une concentration suffisante de nutriments et un fort pouvoir tampon. D’un point de vue biotique, deux communautés distinctes de microorganismes évoluent dans le lixiviat et dans le fumier, sans aucun transfert entre ces deux environnements, limitant ainsi le rôle d’inoculation souvent attribué au lixiviat. Dans un deuxième temps, la réalisation d’un plan d’expérience a permis d’identifier, au laboratoire sur pilotes instrumentés, des paramètres de recirculation du lixiviat qui influencent les vitesses de production de méthane. Ainsi, le temps entre les recirculations, le volume recirculé et le ratio lixiviat/substrat initialement introduit jouent sur la forme des cinétiques de production. En actionnant l’un ou l’autre de ces leviers, il serait potentiellement possible d’adapter la production de méthane, en fonction des besoins des systèmes de valorisation du biogaz en place sur ces installations. Enfin, la méthode de tomographie de résistivité électrique a été utilisée, à grande échelle, pour suivre la percolation du lixiviat à travers le massif et mettre en évidence les disparités de distribution du lixiviat dans le massif. Cette étude a montré que la géométrie du réseau de recirculation du lixiviat, consistant en un tuyau perforé parcourant la surface du massif dans le sens de la longueur, ne permettait pas un écoulement homogène du lixiviat dans les digesteurs. Certaines zones n’ayant jamais été humidifiées, la production de méthane se trouve réduite et les rendements amoindris. Cette thèse s’articule autour de plusieurs analyses multi-échelles et complémentaires permettant de mieux comprendre le rôle du lixiviat, d’améliorer sa mise en œuvre et son utilisation pour la digestion anaérobie des fumiers de bovins. / With 67 Mt of cattle manure recovered every year, France has a significant source of agricultural waste to be valorised through anaerobic digestion. Batch mode solid state anaerobic digestion (SSAD) process with leachate recirculation seems to be the most suitable technique to valorise that kind of waste, which contains high total solid content (>20%). Currently, this process is rare on French territory. To develop batch mode SSAD, various technical and scientific barriers must be straightened out, and particularly those concerning leachate recirculation. The objective of this work is to optimize SSAD of agricultural was (mostly cattle manure) by pointing out the most favorable settings that allow producing high volumes of biogas, steadily and within a short time, taking into account the particular technical constraints of this process. First of all, the objective was to better understand the biological role of leachate in the batch mode SSAD process. For that purpose, four leachates with different origins were used. Two of them were biologically active (from existing digesters) while the two others were sterilized. It was demonstrated an effective anaerobic digestion was favored by using a leachate gathering the following abiotic characteristics: an adequate pH, a strong buffer capacity and the presence of the right concentration of nutrients. From the biotic point of view, dedicated communities of microbes were in progress in each liquid and solid environment with nested relationship. The role of leachate as inoculum was then limited. In a second part, the influent parameters of leachate recirculation were identified at laboratory scale, by setting up a design of experiment. It was found that the elapsed time between two recirculations, the recirculated volume of leachate and the initial leachate to substrate ratio introduced in the reactor could modify the shape of methane production rate. By changing one or several of those parameters, it would be possible to control and adapt methane production rate to the specific constraints of one SSAD plant. In the last part, the Electrical Resistivity Tomography (ERT) method was used, at full scale, to monitor the leachate percolation through the solid waste and highlight leachate distribution disparities. It was shown the leachate injection system consisting of a perforated pipe laying on the solid top surface was not efficient to evenly moisten the solid waste. From that observation, it was concluded that cumulated methane production could be improved if areas that were not in contact with leachate could be moistened by using another leachate injection system. This manuscript was based on several multi-scale and complementary analyses that allow a better understanding of the role of leachate during SSAD process and an improvement of its utilization for the anaerobic digestion of cattle manure.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17542号 / 工博第3701号 / 新制||工||1563(附属図書館) / 30308 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 高岡 昌輝, 教授 田中 宏明, 教授 米田 稔 / 学位規則第4条第1項該当

To increase profitability for biogas production, new innovative substrates and condition of operations needs to be implemented. At the current state, fats, oils and greases (FOGs) represent a promising substrate even though it brings operational challenges to the anaerobic digestion process. By utilizing hydrodynamic cavitation (HC) as a pre-treatment of the FOGs, the efficiency of FOGs’ co-digestion with wastewater sludge can be significantly improved. Preliminary experiments conducted on oil and water demonstrates that the HC pre-treatment improves the oil solubilisation as well as forms stable oil and water emulsion that last for several hours. The pre-treatment also improved the soluble chemical oxygen demand (COD) of biosludge (BiSl) by up to 115% and the initial degradation rate by up to 35%. In a semi-continues system, this allowed a significant increment in the specific methane yield depending on the organic loading rate (OLR) applied1. With sufficient process optimization, the HC-pre-treatment may prove to be an energy efficient and effective pre-treatment of FOGs.

Biogas production from energy crops grown on arable land often competes with food and feed production. Wetland plants offer an alternative source of biomass as well as offering a number of environmental benefits such as nutrient removal from wastewaters, carbon sequestration and reducing the use of mineral fertilizer. The aim of this study is to investigate the effect of harvest time on biogas production of Phragmites australis and Glyceria maxima and to perform a cost-benefit analysis of using these wetland plants as a substrate for biogas production. The results of the batch experiment show that the overall biogas production and specific methane yields of biomass harvested in June was higher than biomass harvested in September due the increased lignocellulosic nature of the more mature September plant. The cost-benefit showed that in Sweden it is not currently profitable to solely use wetland plants for biogas production. For both species the highest costs were seen in the June harvested biomass, this was due to the much higher fresh weight and increased transportation costs. For both species the highest revenues generated were the June harvested biomass, this was due to the higher specific methane yields. It was found that the harvest time that was closest to profitability from both species was the June harvest for Phragmites australis. Although the costs were higher for harvesting in June, this was outweighed by the higher amount of electricity produced for this scenario. If transportation distance was to be increased it could result in September being the favourable harvest time. Therefore, individual circumstances of the farmers could decide which is the optimal harvest time. Although solely using wetland plants for biogas production is not currently profitable, co-digestion and pre-treatment are options to investigate that could change this. Also if a greater financial value is put on the socioeconomic benefits such as increased biodiversity, aesthetic value and global warming mitigation it may be financially viable in the future.

Das Ziel dieser Arbeit ist es biobasierte, bioabbaubare Biokunststoffe mit einfacher Prozesstechnik zu desintegrieren und für anaerobe Mikroorganismen verfügbar zu machen. Mittels der Ergebnisse der Untersuchungen soll nachgewiesen werden, dass eine anaerobe Verwertung der desintegrierten Biokunststoffe bzw. der generierten Flüssigkeiten möglich ist. Außerdem soll ermittelt werden, welches energetische Potenzial dabei freigesetzt wird. Im Rahmen einer Wirtschaftlichkeitsbetrachtung wird die Implementierung einer Desintegrationsstufe in einer Vergärungsanlage bewertet. Zu Beginn der Untersuchungen wird festgestellt, dass eine anaerobe Verwertung im mesophilen und im thermophilen Bereich nur unzureichend realisierbar ist. In den anschließenden Untersuchungen werden Maßnahmen zur Beschleunigung der Desintegration von zertifizierten bioabbaubaren Biokunststoffen untersucht. Nachdem ein Nachweis der Desintegration verschiedener Biokunststoffe erbracht und aus-reichend hohe Gehalte gelöster Organik nachgewiesen werden, erfolgt im Anschluss die anaerobe Verwertung der erzeugten Flüssigkeiten in einer mesophilen, kontinuierlichen Vergärung. Die Gärtests geben Aufschluss über die Vergärbarkeit, das Biogaspotenzial, die Biogasqualität und die Abbaugrade der desintegrierten Biokunststoffe. Der höchste Abbaugrad (71,3 %) wird bei der Untersuchung der Flüssigkeiten der Ecovio®-Biobeutel erreicht. Der Abbau der Activia®-Becher (39,6 %) verlief weniger effizient und wird durch hohe Gehalte organischer Säuren und Verdünnungseffekte beeinflusst. Die real erzeugten Biogaspotenziale schwanken zwischen 0,1 lN CH4/g CSB und 0,23 lN CH4/g CSB. Die Biogasqualität während der Versuche ist sehr gut. Die Verhältnisse von CH4 zu CO2 liegen überwiegend zwischen 50:50 und 60:40. Der Nachweis der energetischen Nutzbarmachung der desintegrierten Biokunststoffe für den mikrobiellen Umsatz bzw. zur Biogasbildung wird erbracht. Die Implementierung einer Desintegrationsstufe in eine bestehende Vergärungsanlage wird im Hinblick auf die Wirtschaftlichkeit bewertet. Die Implementierung ist technisch realisierbar. Die Kosten der Implementierung übersteigen die Erlöse um ein Vielfaches. Auch bei längeren Betrachtungszeiträumen kann kein Gewinn erwirtschaftet werden.

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%.

Several commercially available reverse osmosis (RO) membranes were characterized with aqueous solutions of ammonium sulfate, potassium triphosphate, and mixtures of these two salts at different feed concentrations, compositions and pressures. The objective of this study was to investigate the rejection of these solutes, in particular the ammonium ion (NH4+), by different RO membranes. The aqueous solutions were assumed to come from an anaerobic digester via a process, currently under investigation by CHFour Biogas Inc., to maintain low concentrations of ammonia in the digester in order to maximize the biogas production. The ammonium ions present in the liquid produced from the process are then concentrated using membrane separation. The concentrated ammonium solution would be a valuable fertilizer that could be used by agriculture. The membranes were characterized with three models: the solution-diffusion model, the Kedem-Katchalsky model, also known as the irreversible thermodynamics model, and the Donnan Steric Pore Model (DSPM). The solution-diffusion and irreversible thermodynamics models were found to be inadequate for proper membrane characterization and the use of the DSPM model yielded membrane properties in good agreement with those found in already existing literature. The pore radius of investigated membranes ranged from 0.39 to 0.51 nm. The effect of pH on membrane surface charge was also studied, with the conclusion that increases in pH led to increasingly negative surface charges. This affected the transport of individual ions through the membrane due to preferential passage of the counter-ions. The effects of applied pressure on the stoichiometric nature of salt rejections were also studied. The minimal observed rejection from the range of experiments carried out using ammonium sulfate was 93%Non-stoichiometric rejections of ions were also observed in the experiments with single and multiple solutes. Furthermore, the rejection of ammonium ions in the presence of other ions (K+, SO42-, PO43-) increased as feed concentration increased, which was a result of the synergistic effects of feed pH and ionic interactions. The minimum NH4+ rejection in the presence of other ions was 95.4%, which suitability using RO membranes for concentration of ammonium from dilute aqueous solutions.

Avloppsreningsverket Sundet i Växjö har en rötningsanläggning som producerar biogas. Anläggningen består idag av två rötkammare och en maskin för avvattning som substratet går igenom efter rötningen. Substratet som används i rötningsprocessen är avloppsslam från Växjö. Planer finns på att utöka processen med en tredje reaktor i vilken det rötade slammet ska återrötas. Detta för att få ut mer biogas ur slammet. Det rötade slammet från reaktor 1 och 2 planeras genomgå tre förbehandlingssteg i form av fasseparering, sönderdelning och hygienisering innan det går till den tänkta reaktor 3. I arbetet genomförs ett rötningsförsök av rötat slam från Sundet med hjälp av satsvisa reaktorer som ska representera den planerade tredje reaktorn. Syftet med arbetet är därmed att undersöka hur mycket mer biogas det går att utvinna genom en andra rötningsprocess. Beräkningar på hur mycket energi det kommer gå åt i förbehandlingsstegen och hur mycket extra energi som går att utvinna i form av biogas från rötningsförsöket utfördes i arbetet. Resultaten visar att det går att utvinna mer metanrik biogas ur slammet och att förbehandlingsstegen fasseparering och sönderdelning kostar små mängder energi i förhållande till hur mycket extra energi som den extra biogasen ger. Hygieniseringen beräknas kosta förhållandevis mycket energi jämfört med den energin från den producerade biogasen. / The municipal waste treatment plant Sundet in Växjö currently has a digestion plant producing biogas. The facility consists of two digesters and a machine that dewaters the sludge after the reactors. The substrate that is used in the reactors consists of sewage sludge from Växjö. There are plans to expand the process with a third reactor in which the digested sludge will be digested a second time in order to extract more biogas. The digested sludge from reactor 1 and 2 is planned to undergo three pretreatment steps in the shape of phase separation, decomposition and sanitation before it reaches reactor 3. In the thesis a digestion process is carried out with digested sludge from Sundet in batch reactors that represents the planned third reactor. The purpose is to analyze how much extra biogas that can be extracted with a second digestion process. Calculations of how much energy that is necessary for the pretreatment stages and how much extra energy that can be extracted in the shape of biogas from the digestion process was made in the thesis. The results from the experiments shows that it is possible extract more methane rich gas from the sludge and that the pre treatment stages phase separation and decomposition use small amounts of energy compared to how much energy the extra gas gives. The sanitation process is estimated to cost quite a lot of energy compared to the energy extracted through biogas.

Orientador: Ariovaldo José da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-27T23:32:57Z (GMT). No. of bitstreams: 1 Silva_DouglasBatistada_M.pdf: 2490257 bytes, checksum: 46f41b6961223169590146af18566274 (MD5) Previous issue date: 2015 / Resumo: A crescente demanda por fontes de energia renováveis vem direcionando esforços e interesses por pesquisas focadas no desenvolvimento de biocombustíveis, a partir da digestão de resíduos provenientes de atividades agrícolas e agroindustriais. Neste contexto, a digestão anaeróbia pode ser direcionada para a produção e aproveitamento de subprodutos intermediários com alto valor agregado, como, por exemplo, etanol e butanol. O objetivo geral deste trabalho foi avaliar o desempenho de reatores anaeróbios de leito fixo e fluxo ascendente no tratamento de água residuária, visando à produção biológica de butanol e etanol a partir de uma cultura mista de micro-organismos selvagens. Foram utilizados dois reatores anaeróbios de leito fixo, com volume total de 3,77 litros. O primeiro reator foi mantido em condição acidogênica e o segundo em condição solventogênica. Os reatores foram operados em cinco diferentes etapas com tempo detenção hidráulica (TDH) de 2, 4 e 12 h e alimentados com água residuária sintética preparada para resultar em DQO em torno de 500 mg L-1, 1.000 mg L-1, 4.000 mg L-1 e 12.000 mg L-1, tendo como principal fonte de carbono sacarose. Além disso, foram avaliadas duas condições de temperaturas diferentes, ambiente (variando de 25ºC a 30ºC) e controlada (35ºC). Em cada etapa também foi avaliada a influência do efeito da recirculação do biogás no desempenho dos reatores, operando-os por um período de 30 dias sem recirculação de biogás e 30 dias com recirculação de biogás. Os resultados mostraram que a suplementação de bicarbonato de sódio no preparo do afluente auxiliou no aumento da capacidade de tamponamento do sistema e a recirculação de biogás favoreceu a estabilidade nos valores de pH durante todo o período experimental nessa condição. A variação crescente do tempo de detenção hidráulica (TDH) e da concentração de matéria orgânica (DQO) conduziu a um aumento na concentração de ácidos voláteis totais (AVT) e na concentração de produtos intermediários resultante da fermentação da sacarose. A concentração média de AVT variou de 89,3 mg L-1 da etapa I para 147,0 mg L-1 na etapa II, quando houve aumento do TDH e da DQO afluente. A variação da temperatura não influenciou a produção de AVT, na etapa III na qual a temperatura foi variável a concentração média de AVT detectada no efluente foi 546,0 mg L-1 e na etapa IV, com temperatura mantida em 35°C a concentração média de AVT no efluente foi 530,4 mg L-1. O melhor desempenho na produção de etanol foi verificado no reator solventogênico, com o pH em torno de 4,5, quando mantido com temperatura controlada a 35°C, TDH de 4 horas e taxa de carregamento orgânico (TCO) de 24 g DQO m-3d-1, sem recirculação de biogás. Nessa condição a concentração média de etanol detectada no efluente foi de 929,52 mg L-1. A produção de etanol não correspondeu ao aumento da TCO aplicado na etapa V, mantendo a concentração média de 993,35 mg L-1 na fase com recirculação de biogás. Butanol foi detectado em concentrações muito baixas, é provável que as condições de pH, tipo de reator e a estratégia de inoculação foram inadequadas para viabilizar a rota metabólica de produção de butanol / Abstract: The growing demand for renewable energy sources has been directing efforts and interests by research focused on the development of biofuels from waste digestion from agricultural and agro-industrial activities. In this respect, anaerobic digestion can be directed to the production and use of intermediates by-products with high added value such as, for example, ethanol and butanol. The aim of this study was to evaluate the performance of anaerobic fixed bed and upward flow in the treatment of wastewater, aiming to organic production of butanol and ethanol from a mixed culture of wild microorganisms. We used two anaerobic fixed bed, with a total volume of 3.77 liters. The first reactor was kept in acidogenic condition and the second in solventogenic condition. The reactors were operated in five different stages with hydraulic retention time (HRT) of 2, 4 and 12 h fed synthetic wastewater prepared to result in COD around 500 mg L-1, 1,000 mg L-1, 4,000 mg L -1 and 12,000 mg L-1, the main carbon source sucrose. In addition, we evaluated two different conditions of temperature, environment (ranging from 25 ° C to 30 ° C) and controlled (35 ° C). At each step was also evaluated the influence of the effect of recirculation of the biogas reactor performance, operating them for a period of 30 days without recirculation of the biogas and 30 days with biogas recirculation. The results show that supplementation of sodium bicarbonate in the preparation of the influent assisted in increased system capacity and buffering biogas recirculation favored stability in pH during the entire experimental period in this condition. The increasing variation of hydraulic retention time (HRT) and the concentration of organic matter (COD) led to an increase in the concentration of volatile fatty acids (VFA) and the concentration of intermediate products resulting from the fermentation of sucrose. The average concentration of AVT ranged from 89.3 mg L-1 from step I to 147.0 mg L-1 in step II, when an increase of the HDT and the influent COD. The variation in temperature did not affect the production of AVT in step III in which the temperature varied from the mean concentration in the effluent was detected AVT 546.0 mg L-1 and stage IV with temperature maintained at 35 ° C the concentration AVT average of the effluent was 530.4 mg L-1. The improved performance in ethanol production was observed in solventogênico reactor with pH around 4.5, when kept at a temperature controlled at 35 ° C for 4 hours and TDH organic loading rate (TCO) 24 g COD m-3d-1, without recirculating the biogas. In this condition average ethanol concentration was detected in the effluent 929.52 mg L-1. Ethanol production did not correspond to the increase in TCO applied to the V phase, keeping the average concentration of 993.35 mg L-1 in phase with biogas recirculation. Butanol was detected at very low concentrations, it is likely that the conditions of pH, type of reactor and inoculation strategy have been inadequate for enabling the metabolic pathway of butanol production. Keywords: anaerobic digestion, solventogenic, butanol and ethanol / Mestrado / Agua e Solo / Mestre em Engenharia Agrícola

Lipídeos contidos em resíduos de laticínios além de representarem uma perda industrial importante, interferem negativamente nos sistemas de tratamento de efluentes inibindo a atividade microbiana do consórcio (Mendes, 2005). O objetivo do presente trabalho foi estudar a degradação anaeróbia de gorduras do leite hidrolisadas com duas enzimas: lipase comercial de Candida rugosa (éster-inespecífica), e preparado enzimático de Geotrichum candidum (lipase éster-específica). Determinaram-se condições ótimas de hidrólise de gorduras do leite no tocante a tempo e temperatura de processo. Após esta etapa, determinou-se a produção metanogênica advinda da estabilização de esterco bovino combinado com gorduras de laticínios hidrolisadas e in natura. As condições ótimas de ação de lipase comercial de C. rugosa em gorduras do leite foram obtidas com temperatura de 40ºC e pH de 6,5. As condições ótimas de ação de preparado enzimático de G. candidum foram obtidas com temperatura de 40ºC e pH de 7,5. Os tempos de processo hidrolítico para a produção máxima de ácidos graxos foram de 8 horas e 16 horas quando se utilizaram preparado enzimático de G. candidum e solução de lipase comercial de C. rugosa respectivamente. As velocidades de processo, bem como os valores de biodegradabilidade anaeróbia, produção metanogênica específica e coeficiente de conversão (Yp/s) indicaram ser muito mais eficiente a utilização lipase de C. rugosa na hidrólise das gorduras do leite, quando o objetivo do processo é a produção de biogás. Além disso, o preparado enzimático de G. candidum ocasionou inibição da atividade metanogênica acetoclástica. Quando se realizou um estudo variando-se a concentração de gordura no tratamento enzimático, obteve-se a maior produção de ácido oléico quando se utilizaram 42 gramas de gordura por grama de enzima. Por outro lado, o melhor fator de conversão entre produto e substrato foi verificado quando a relação entre a massa de gordura e a massa de enzima foi igual a 6g/g. / Lipids in dairy waste as well as representing an important industrial loss, interfere negatively in wastewater treatment systems by inhibiting microbial activity of the consortium. The aim of this work was to study the anaerobic degradation of hydrolyzed milk fats using two enzymes: lipase from Candida rugosa, which is an ester unspecific enzyme; and other specific lipase obtained from Geotrichum candidum. Optimal conditions for hydrolysis of milk fat regarding pH, time and temperature were determined. After that, the methanogenic production from the stabilization of cattle manure combined with fats (hydrolyzed and in nature) was evaluated. The optimum conditions for the action of commercial C. rugosa lipase were obtained at 40ºC and pH 6.5. The optimum conditions for the action of G. candidum preparation were obtained at 40ºC and pH 7.5. Maximum product concentrations were obtained within 8 hours and 16 hours when preparation of G. candidum and C. rugosa lipase were used, respectively. The initial methanogenic production rate, the values of anaerobic biodegradation, the specific methanogenic production and the methane yield as well, showed that the use of C. rugosa lipase in the hydrolysis of fats is more efficient when the goal of the process is the production of biogas. The use of the enzymatic preparation of G. candidum did not cause any benefits, and in addition, caused bigger inhibition of acetoclastic methanogenic activity. When the initial concentration of substrate was varied for the enzymatic treatment, it was possible to verify higher oleic acid accumulated production when 42 grams of fat where used per gram of enzyme. On the other hand, the higher conversion factor between product and substrate was obtained when the relation between the mass of fat and the mass of enzyme was 6g/g.