Academic literature on the topic 'Biomethanation'

<p>In the semi-enclosed Baltic Sea, excessive filamentous macro-algal biomass growth as a result of eutrophication is an increasing environmental problem. Drifting huge masses of red algae of the genera <em>Polysiphonia</em>, <em>Rhodomela</em>, and <em>Ceramium</em> accumulate on the open shore, up to five tones of algae per meter beach. During the aerobic decomposition of these algal bodies, large quantities of red colored effluents leak into the water what are toxic for the marine environment. In this study, feasibility of anaerobic conversion of red algae <em>Polysiphonia</em>, rich in nitrogen and phosphorous, was investigated. Biogas and methane potential of <em>Polysiphonia</em>, harvested in two different seasons [October and March], was investigated through three different batch digestion experiments and laboratory scale CSTR [continuous stirred tank reactor] at mesophilic (37^oC) condition. Autoclavation [steam and heat] and ultrasound pretreatments were applied in order to enhance the biodegradation. In STR, anaerobic codigestion of algal biomass with SS [sewage sludge] was applied with a gradual increase in organic loading rate [1.5-4.0 g VS/L/day] and operated for 117 days at 20days HRT [hydraulic retention time]. Reactor digestate was analyzed four times over the period to determine the nutrients and heavy metals content. It is concluded that the methane potential of algae harvested in October is almost two-fold than that of algae harvested in March, probably due to it’s higher [more than double] nitrogen richness. An increase in biogas yield was observed upto 28% and VS reduction was increased from 37% to 45% due to autoclave pretreatment. Ultrasound pretreatment had no effect on digestion. In batch digestion, maximum methane yield 0.25 m³/kg VS added at 273^oK, was obtained from algae [harvested in October] pretreated in autoclave. Codigestion of algae with SS worked well in STR with a comparatively lower OLR. At a higher OLR, methanogens were inhibited due to increased VFAs accumulation and decreased pH. A maximum biogas yield 0.49 m³/kg VS added at 310^oK , was obtained from algae [harvested in October] pretreated with autoclave. The methane content of the produced biogas was 54%. Average [over a short period, day 99-107, reactor showed steady performance] maximum biogas yields from untreated algae obtained 0.44 m3/kg VSadded at 310^oK and the VS reduction was calculated 32%. Digestate, to be used as a fertilizer, was found NH₄-N, N, P, K, S and Na rich and only Cadmium level was above the maximal limit among the heavy metals. The sand content in algae during harvesting was considered as a factor to disrupt the operation. Codigestion of <em>Polysiphonia</em> algal biomass with substrate with higher C:N ratio like paper mill waste should be more appropriate to increase the methane and biogas yield. It is inconclusive whether AD process is a good method to dewater redalgae or not but large scale harvesting of algae will definitely contribute to curb eutrophication of the Baltic Sea through decreasing N and P level.</p>

The goal of this work was to establish the suitable and limiting concentrations of Zn, Cu and Mn compounds during syngas fermentation. The results showed that cells encased in polyvinylidene difluoride (PVDF) membranes had a faster accumulation of methane in reactors containing fermentation medium dosed with 5 mg/L of each heavy metal compared to free cells. It was also revealed that total inhibition of biohydrogen production occurred in medium containing 5 mg/L Cu, 30 mg/L Zn and 140 mg/L Mn while the most suitable metal concentration level was 0.1 mg/L Cu, 0.6 mg/L and 2.8 mg/L Mn. In addition, a comparison test showed that for the most suitable metal concentration in the medium, rate of performance at pH 6 and 7 was higher than at pH 5.

Many of the current methods of assessing anaerobic biodegradability of solid samples require sample modification prior to testing. Steps like sample drying, grinding, re-drying and re-grinding to 2mm or less make the test results difficult to apply to field conditions and could lead to oxygen exposure, possibly distorting the results. Finally, because of a small sample size of about 10-50g w/w, the test result may not be representative of the bulk material. A new tool dubbed ‘tube’ has been developed, made of 10 cm diameter PVC pipe measuring 43.5 cm long with 3600 ml capacity with caps at both ends. For easy sample introduction, one endcap is fixed while the other is screw capped. A distinctive feature is the wide neck opening of about 10 cm where solid samples can be introduced as is, without further sample modification. Research has proven the tube applicable across various types of solid organic waste and conditions provided that a suitable organic loading rate is determined. The tube is best operated using 5-7 days pre-digested digested sewage sludge as seed, with minimal mixing and without the addition of nutrients or alkali solution. The test result can be obtained within 4-6 days to 20 days, signifying a 50-75% and 95% substrate degradation, respectively. Irreproducibility seen in some experiments may not only be a function of the seed and the substrate. The organic loading rate (OLR) at which the test is conducted is also influential especially if test is conducted closer to its maximum OLR tolerance where anaerobic process is more erratic. The performance of a continuous reactor digesting on a similar substrate can be estimated using this new tool. Food waste is established by the tubes to have an ultimate methane potential (B0) of 0.45L CH4/g VS. The same substrate when digested in a continuous reactor will produce about (B) 0.32 L CH4/g VS. The first order rate constant for both systems; batch and continuous are identical at 0.12 to 0.28 d-1. First order kinetics is efficient at modelling the anaerobic degradation when the process is healthy but may be less reliable under an unstable process. This research recommends the use of kinetics in combination with the experimental data (e.g. HRT, OLR, yield) when planning and designing an industrial plant to avoid overdesign and unnecessary building, maintenance and operating costs.

In the last decades increasing attention has been paid on syngas, produced through the thermal gasification of biomass, for energy recovery. Syngas components, mainly CO and H2, can be used as substrate for the conversion into important chemicals and fuels, in this case specifically methane, by a wide range of microorganisms. This study focused on the exploitation of an anaerobic mixed culture, collected from an anaerobic sludge of the Denmark Technical University (DTU) Bioengineering laboratory, in the fermentation of syngas for the production of CH4. A series of enrichment experiments with different initial partial pressure of CO and H2 were performed, in mesophilic and thermophilic conditions. Both yields and production rates resulted to be higher in thermophilic conditions; experiments with H2 tended to be faster than those without and the mmols of produced methane, over fed carbon (mmol/mmol), were higher than when only CO was present as substrate. A second experimental test has also been executed in thermophilic conditions (since they better performed in the previous experiment) to better evaluate which reactions are those which mainly took place during the syngas fermentation process. Experiments were performed both in the absence and in the occurrence of 2-bromoethanesulfonic acid as an effective inhibitor of the methanogens. Results showed that acetate mainly came from Acetogenesis via CO, being however negligible, while methane was produced either by hydrogenotrophic methanogens either via H2/CO. Production of bio hydrogen was also present, and it is usually further consumed to produce CH4. To conclude, findings of this projects may be considered as a further step towards the knowledge of biogas production through the use of microbial catalysts, giving important information both about the optimal operating conditions and about microbial metabolism.

Comme dans les pays du Nord riches, il y a également une augmentation de la production de déchets organiques dans les pays du Sud moins avancés. Connues sous l'appellation de Matières Organiques Exogènes (MOEx), les déchets organiques peuvent être valorisables comme engrais ou amendement pour les sols agricoles ou bien une nouvelle source de biomasse pour la production d'énergie. L'utilisation raisonnée d'une MOEx exige toutefois une connaissance scientifique approfondie de leur nature et de leurs impacts sur l'environnement. Des analyses conventionnelles en laboratoire et des expérimentations doivent être effectués pour maîtriser leur structure complexe liée à leurs propriétés physiques, chimiques et biochimiques. Celles-ci sont généralement longues et onéreuses. Dans notre étude, la spectroscopie proche infrarouge (SPIR) a été choisie comme une alternative aux méthodes classiques pour la caractérisation de ces MOEx en milieu tropical humide. Les objectifs de notre travail sont (1) de montrer que la SPIR est une méthode appropriée pour la prédiction des caractéristiques de MOEx, (2) pour caractériser les MOEx en termes de leur potentiel agronomique et leur potentiel énergétique et (3) pour élaborer une typologie, construite à partir des données prédites par la SPIR, qui prend en compte quelques impacts négatifs liés à l'utilisation des MOEx. L'ensemble des données a inclus plus de 2000 échantillons de MOEx couvrant une large gamme de MOEx fraîches ou transformées issues de l'élevage, de la ville et des agroindustries. Le spectre SPIR de chaque EOM a été acquis. En plus des caractérisations classiques de laboratoire (les dosages de carbone, azote, phosphore, potassium, etc.), d'autres expérimentations ont été conduites en vue d’évaluer (1) les potentiels « positifs » des MOEx : (i) suivi de la minéralisation du carbone et de l'azote mesurée dans des conditions contrôlées pour une valorisation agronomique, (ii) détermination du pouvoir calorifique et du potentiel méthanogène pour une valorisation énergétique ; et (2) les potentiels « négatifs » des MOEx : (i) dénitrification potentielle et (ii) phytotoxicité en présence d’éléments trace métallique. Pour élaborer la typologie, la méthode SIRIS (Système d'Ingration des Risques par Interaction des Scores) a été appliquée pour formaliser les étapes d'une procédure logique menant à une classification des MOEx selon l'objectif de l'orientation de recyclage. La diversité des MOEx est illustrée à titre d'exemple par une large gamme des teneurs en (i) C (de 2 à 64 gC.100g-1MS), (ii) N (de 0,2 à 14gN.100g-1MS), (iii) P total (0,01 à 16gP.100g-1MS), K total (0,04 à 30 gK.100g-1MS). En prenant en compte l'ensemble des MOEx, les étalonnages des modèles SPIR sont acceptables pour la prédiction des teneurs en C, en N, en P et en K. Pour les potentiels « positifs » des MOEx (1) suivant les types de MOEx 102 à 955 kgMO.t-1MOEx pourraient être stockées dans le sol pour le maintien de la fertilité, (2) les pouvoirs calorifiques des MOEx varient de 7 à 28 MJ.kg-1MS et les potentiels méthanogènes vont de 69 à 488 NmlCH4.g-1MO. Quant aux potentiels négatifs, que ce soit pour les émissions de N2O ou pour la phytotoxicité des ETM, une forte interaction entre les propriétés du sol (pH, texture, …) avec les MOEx masque souvent certains effets. La méthode SIRIS a permis de classifier les MOEx selon un processus simple basé sur le classement de critères et de scores d'auto-pénalisation. Cette approche est intéressante en l'absence de données précises qui sont souvent difficiles à obtenir. L'aide des prédictions par la SPIR nous a été utile pour cette démarche d'orientation de la valorisation agronomique et/ou énergétique des MOEx. Des approches socio-économiques devraient compléter notre étude pour aboutir à l'orientation finale de valorisation des MOEx<br>As observed in northern/rich countries, there is an increase in the production of organic wastes in southern/less advanced countries. So called, Exogenous Organic Matter (EOM), they can be a valuable fertilizer or amendment for agricultural soils or a new supply for energy production. The safe utilisation of EOM requires an in-depth scientific knowledge of their nature and impacts on the environment. Laboratory analysis and experiments have to be carried out in order to know their complex structure related to their physical, chemical and biochemical properties. These techniques represent a relatively high cost and are time consuming. In this study, the near infrared spectroscopy (NIRS) was chosen as an alternative to classical methods for laboratory characterisations of tropical EOM. The objectives of this study are (1) to show that NIRS is a suitable method for predicting EOM characteristics (2) to characterize EOM in terms of their agronomic potential and/or energetic potential, and (3) to elaborate a typology, build with predicted parameters by NIRS, taking into account some environmental impacts of the different utilisations of EOM.The dataset included more than 2000 EOM samples covering a broad range of fresh and transformed organic materials. Each EOM was scanned using a NIR spectrometer from 1100nm to 2500nm. In addition to the classical laboratory characterisations (dosages of total carbon, nitrogen, phosphorus, potassium), other experiments have been carried out: (1) for “positive” potentials: (i) C and N mineralization measured in controlled conditions (for an agronomic use), (ii) determination of High Heating Value and Biochemical Methane Potential (for an energetic use) and (2) for “negative” potential or risk: phytotoxicity assessment due to trace elements, and the determination of potential nitrous oxide emission. To elaborate the typology, the SIRIS method (System of Integration of Risk with Interaction of Scores) was carried out in order to formalize the steps of a logical procedure, leading to a decision according to objective of the recycling orientation.Diversity of EOM is illustrated by the variability of (i) C contents (from 2 to 64 gC.100g-1DM); (ii) N contents (from 0.2 to 14gN.100g-1DM); (iii) total P contents (from 0.01 to 16gP.100g-1DM),(iv) total K contents (from 0.04 to 30 gK.100g-1DM). When taking into account all EOM without regarding their nature, acceptable predictive models were obtained with NIRS calibration for estimating C, N, total P and total K contents for EOM.“Positive” potential assessment provided information about (1) remaining organic carbon might be stocked into soil after applying EOM (from 102 to 955 kg.t-1TOM) (2) High Heating Value of EOM when recycling as a supply of small scale combustion or thermo chemical conversion (from 7 to 28 MJ.kg-1DM), (3) Biochemical Methane Potential after EOM anaerobic digestion (from 69 to 488 NmlCH4.g-1TOM). Both “negative” potential which took into account phytotoxicity due to trace elements and nitrous oxide emissions were highly interacted on the soil properties (pH, texture). The SIRIS method appeared to be an efficient decision-making tool in this study. It made it possible to classify the EOM according to a simple process based on the ranking of criteria and a self-penalization scoring system. This approach can be used in the absence of accurate, reliable data, which are often difficult to obtain. The help of NIR prediction was useful for better orientate the EOM valorization between soil fertilization and energy production. Further concern will be focused on socio-economical approach in order to complete the final destination of EOM re-use

O modo de vida da humanidade demanda novas alternativas às fontes energéticas fósseis, precisa garantir a produção de alimentos e energia para uma população que já ultrapassa 7 bilhões, além de ter de gerir seus Resíduos Sólidos &#40;RS&#41; e efluentes &#40;esgoto&#41;, em que grande parte dos primeiros, são enterrados em aterros sanitários e&#47;ou lixões, gerando problemas sanitários e ambientais e desperdício de nutrientes para a agricultura. Parte dessa tripla solução energética&#47;alimentar&#47;sanitária pode vir dos recursos contidos nos Resíduos Biodegradáveis &#40;RB&#41;, ou como dito na Lei Brasileira N&#186; 12.305 - &#34;Resíduos Orgânicos&#34; &#40;RO&#41;, que podem ser biometanizados para gerar gás combustível, metano, CH4 e/ou gás hidrogênio, H2 e posterior uso do sólido e líquido resultante na forma de substrato para a agricultura, ou processos fotossintéticos aquáticos mediados por microalgas e macrófitas. Paralelamente ao tratamento anaeróbio, se os RO forem tratados aerobicamente, via compostagem e/ou vermicompostagem, não se gera nenhum gás combustível que possa ser usado em outro momento e local, apenas calor. Diante desse quadro, se propõe uma alternativa para o tratamento de resíduos biodegradáveis e efluentes domésticos em zonas rurais e periurbanas, por meio da proposta de uma pequena central de tratamento de resíduos orgânicos composta por uma lagoa facultativa com geração e coleta de biogás, associada com um sistema de hidrolisação de resíduos sólidos orgânicos e de tratamento de biogás, havendo a separação do CO2 em fase aquosa para alimentação de carbono e alcalinidade ao sistema de bacia de fotossíntese de microalgas e macrófitas do gênero lemna. Foram realizados balanços de água, nutrientes, eletricidade e monetário para aferir a consistência teórica para futura aplicação dos projetos e suprir as três demandas&#47;soluções citadas. Foi possível aferir que o custo do metro cúbico de gás metano gerado ficou em torno de 0,5- 4 R&#36;.m-3 de gás metano. Foi possível propor um projeto para se caminhar no sentido de poder dar base a trabalhos futuros, que desenvolvam métodos inovadores de gestão de resíduos para serem aplicados no Brasil, com o fim de descentralizadamente adequar os municípios ao PNRS, ao mesmo tempo em que se cria na nação o conceito de biorrefinaria, integrando-a ao saneamento básico e ambiente, em prol da soberania individual energética&#47;alimentar&#47;hidrológica dos brasileiros.<br>People&#39;s way of living demands alternatives to fossil energy, needs to produce food for a population that has already reached more than seven billion and has to deal with waste generation, namely solid wastes and sewage, while most of the first are buried in landfills or even dumped, generating sanitary and environmental problems while wasting nutrients for agriculture. Part of that triple energy&#47;food&#47;sanitation solution can come from biodegradable wastes, or like the way is said on Brazilian Law N&#186;12.305 - &#34Organic Wastes&#34;, that can be converted into biogas, methane or hydrogen gas, and subsequent use of solid and liquid digestate for agriculture, or aquatic photosynthetic processes mediated by microalgae and macrophytes. Paralel to anaerobic treatment, if organic wastes are aerobically treated, by compoting and&#47;or wormcomposting, not any renewable gas will be generated for later use, it just generates heat. By this cenario, this master thesis propose and evaluate, technological alternatives for biodegradable waste and wastewaters in cities vicinities and&#47;or rural areas nearby urban areas by proposing a small biodegradable waste treatment plant composed of a facultative lagoon with biogas generation on its bottom, associated with a system of solid waste hydrolysis built inside a shed which realizes biogas treatment as well, with carbon dioxide gas liquid separation for carbon and alkalinity feeding the multispecies photosynthesis bowl, half consisted of dispersed microalgae and the other half composed of macrophyte of lemna genera. Water, nutrients, electricity and money balances were done in order assess the theoretical consistency for future development of those projects and quench the three cited demands/solutions. It was possible to affirm that the cost of a cubic meter of methane gás is around 0,5 &#8211; 4 R&#36;.m-3. Projects were proposed, that can develop innovative methods for biodegradable waste management to be done in Brazil, with the ultimate goal of adequating towns to the National Solid Waste Policy &#40;Política Nacional de Resíduos Sólidos &#8211; PNRS in portuguese&#41; in a decentralized manner, meanwhile it helps to create alog the nation the biorefinery concept, integrating itself into waterworks, sanitation and the environment, feeding individuals energy, food and hydrological sovereignity of brazilians.

A l'ère de la transition énergétique et en lien avec l'accord international sur la transition vers une économie climatiquement neutre à l'horizon 2050, des recherches intensives sont menées dans le monde sur les énergies renouvelables. Du fait du caractère intermittent et imprévisible de leur fonctionnement, le problème du stockage de l'énergie produite en excès devient un problème très important. On parle actuellement d'une grande capacité de stockage de grandes quantités d'électricité provenant de cellules photovoltaïques et d'éoliennes. L'électricité étant mutuellement convertie en hydrogène et inversement, son stockage dans les couches géologiques sous forme de gaz devient la solution optimale. La conversion de l'électricité renouvelable en H2 peut se faire par électrolyse. Le processus est réversible à l'aide de piles à combustible, où l'hydrogène est converti en courant électrique. On obtient la chaîne : power - to gas - to power. En conséquence, il n'y a pratiquement pas de gaz à effet de serre, ce qui peut conduire à la décarbonation du secteur des transports et des industries énergivores. Dans cette thèse, nous analysons le stockage de l'hydrogène dans des milieux poreux souterrains, qui peuvent être des aquifères, ou des réservoirs de gaz épuisés, ou des ex-stockages de gaz naturel. Le sujet de cette thèse est l'analyse hydrodynamique du transport des gaz injectés dans un stockage couplé à la dynamique bactérienne. Comme le montrent les études précédentes, l'hydrogène est consommé de manière intensive par différents types de bactéries, qui le transforment en méthane par exemple. Les effets croisés des bioréactions et du transport conduisent à la formation de structures spatiales complexes appelées modèles qui conduisent à une distribution non uniforme de l'hydrogène sur le domaine. Notre attention principale s'est concentrée sur l'impact de l'hétérogénéité moyenne sur la formation de motifs. Deux types d'hétérogénéité ont été analysés : la double porosité, selon le modèle macroscopique de Barenblatt, et l'hétérogénéité induite par les bactéries dont la croissance crée la zone de pores réduits voire totalement obstrués<br>In the era of energy transition and in connection with the international agreement on the transition to a climate-neutral economy by 2050, intensive research is being carried out around the world on renewable energy sources. Due to the intermittent and unpredictable nature of their functioning, the problem of storing excessively produced energy becomes a highly important problem. We are currently talking about a large capacity for storing large amounts of electricity coming from photovoltaic cells and windmills. Since electricity is mutually converted to hydrogen and vice versa, storing it in geological strata in the form of gas becomes the optimal solution.The conversion of electricity into H2 can be done by electrolysis. The process is reversible using fuel cells, where hydrogen is converted into electrical current. We obtain the chain: power - to gas - to power. As a result, there are virtually no greenhouse gases, which can lead to the decarbonization of the transport sector and energy-intensive industries.In this thesis, we analyze the storage of hydrogen in underground porous media, which can be aquifers, or depleted gas reservoirs, or ex-storages of natural gas.The subject of this thesis is the hydrodynamic analysis of transport of injected gases in a storage coupled with bacterial dynamics. As shown in previous studies, hydrogen is intensively consumed by various types of bacteria, which transform it into methane, for example. The cross-effects of bioreactions and transport determine the formation of complicated spatial structures called patterns that lead to a nonuniform distribution of hydrogen over the domain. Our main attention was focused on the impact of medium heterogeneity on pattern formation. Two types of heterogeneity were analyzed: the double porosity, in terms of the macroscopic Barenblatt’s model, and the heterogeneity induced by bacteria, growth of which creates the zones of reduced permeability or even completely clogged pores