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Resumo: Investigou-se a influência da utilização de inóculos sobre a digestão anaeróbia de resíduos de aves de postura, frangos de corte e suínos em biodigestores modelo batelada com volume útil de 60 L operados à temperatura ambiente, por meio da caracterização do potencial e distribuição da produção de biogás ao longo do tempo, o estudo da redução de sólidos, a análise das características dos efluentes quanto à concentração de ácidos graxos voláteis e por meio da determinação do número mais provável (NMP) de coliformes fecais e totais nos afluentes e efluentes. Avaliou-se também a atividade metanogênica nos biodigestores com 10 % de inóculo. Foram testadas três concentrações de inóculo: 0, 10 e 15 %. Os resultados mostraram que os resíduos de aves de postura, frangos de corte e suínos são bons substratos para o processo de digestão anaeróbia, apresentando potenciais médios que variaram de 0,3828 a 0,4403 m3, de 0,3495 a 0, 3915 m3, e de 0,1949 a 0,4466 m3 de biogás por kg de ST adicionados, respectivamente para resíduos de aves de postura, frangos de corte e suínos. Com base em todos os parâmetros estudados, as concentrações de inóculo que promoveram melhores resultados foram 10 % para resíduos de aves de postura e frangos de corte, e 15 % para resíduos de suínos. O tratamento anaeróbio revelou-se eficiente na remoção de coliformes totais e fecais independente da concentração de inóculo, alcançando porcentagens médias de redução de NMP que variaram de 99,71 % de 1,09 x 102 a 100 %. A atividade metanogênica específica foi mais elevada nas amostras provenientes dos biodigestores operados com resíduos de aves de postura (0,0340 mmol CH4 g-1 SV h-1), seguida pelos resíduos de frangos de corte (0,0188 mmol CH4 g-1 SV h-1) e suínos (0,0029 mmol CH4 g-1 SV h-1). Estes resultados parecem estar mais associados aos teores...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study was carried out in 60 L volume batch digesters at ambient temperature and investigated the inoculums concentration effects on anaerobic digestion of laying hens, poultry and piggery wastes through evaluation of potential and distribution of biogas production along the time, solids removal, analyze of volatile fatty acids efluent concentration and by monitoring the most probable number (MNP) of total and faecal coliforms in the inffluents and effluents. Specific methanogenic activity (SMA) into the 10 % inoculum digesters was also measured. Three inoculum concentrations (0, 10 and 15 %) were tested. Results showed that laying hens, poultry litter and piggery wastes are good substrats to anaerobic digestion. The potential biogas production varied from 0.03828 to 0.4403 m3, 0.3495 to 0.3915 m3 and 0.1949 to 0.4466 m3 of biogas kg-1 of total solids added, respectively for laying hens, poultry and piggery wastes. The best results for inoculum concentration were 10 % for laying hens and poultry wastes, and 15 % for piggery wastes. Anaerobic digestion was efficient for reduction of the most probable mean number of total and faecal coliforms. Reduction of MNP mean varied from 99.71 of 1,09 x 102 to 100 %. SMA test showed the best activity was from laying hens wastes (0,03400 mmol CH4 g-1 SV h-1), followed by poultry wastes (0,01877 mmol CH4 g-1 SV h- 1) and by piggery wastes (0,00293 mmol CH4 g-1 SV h-1). Results of SMA test appear to be most affected by volatile solids content of the samples than the best ability of the microrganisms to convert substrate. The best organic load rate for activity test were 0,25 g DQO g-1 SV. / Orientador: Jorge de Lucas Junior / Coorientador: Roberto Alves de Oliveira / Banca: Rosana Filomena Vazoller / Banca: Edson Aparecido Abdul Nour / Mestre

Ever since 1976, livestock farmers in Fiji have been intrigued about biogas digesters as an animal waste management measure, but the concept has never evolved into one that is sustainable. Renewed interest came in 1997 after a better Chinese Modified Dome (CMD) design was established, with this came government funding, however by 2002, some failure was also observed. This study set out to investigate the reasons why biogas digesters have never been established as a sustainable concept, its effectiveness as an animal waste management tool and what changes if any, can be made to try and influence the further development of the concept in Fiji. In order to achieve the objectives, which were simply obtaining the answers to the questions presented above, several different approaches had to be followed. This study was the first on biogas digesters in Fiji and it was unique in the sense that the major component dealt with the social aspects of farmers in relation to their biogas digesters. Basically the study was carried out in two parts - desktop studies and field studies. Desktop studies were done to better understand the situation while the field studies included semi-structured interviews with the farmers as well as the collection of biophysical data. Twelve outcomes are presented in chapter 7 of this paper. Two in particular are the improvement of construction and maintenance, which can only come about through training. The research questions are also answered in chapter 7, with recommendations put forward on possible directions to take in terms of trying to influence the development of the concept in Fiji / Master of Science (Hons)

Banco do Nordeste do Brasil / A presente dissertaÃÃo propÃe a implementaÃÃo de um sistema de aquisiÃÃo de dados, controle e monitoramento de uma planta de geraÃÃo de energia elÃtrica acionada por biogÃs. Foi realizado o estudo experimental das estratÃgias de modelagem, identificaÃÃo e controle aplicado ao controle de vazÃo da planta de biogÃs do LaboratÃrio de Energias Alternativas - LEA da Universidade Federal do Cearà - UFC. Foi utilizado e testado para o controle de vazÃo de biogÃs o controlador PI paralelo, alÃm de realizar a comparaÃÃo com o controle existente (controle centrÃfugo) do conjunto motor/gerador. Para vericar a resposta do gerador movido a biogÃs, foi inserido uma carga correspondente a 60% da potÃncia nominal. O sistema proposto reduziu a intervenÃÃo humana no ajuste de vazÃo da vÃlvula de expansÃo. Os resultados demonstraram que o tempo de resposta para estabilidade apÃs a introduÃÃo do contolador PI ao controlador original permitiu a reduÃÃo do tempo de resposta para estabilidade em no mÃnimo 20% mostrando uma resposta satisfatÃria e boa estabilidade para a transiÃÃo da gasolina para o biogÃs, com amplitude de 10 Hz e 8 segundos para estabilizaÃÃo do sistema sem carga. A aÃÃo foi considerada viÃvel para automatizar o processo de partida do conjunto motor/gerador. / The present dissertation proposes the implementation of a data acquisition system, control and monitoring of a electricity generation plant powered by biogas. The experimental study of the modelling strategies, identication and control was done applied to ow control of the biogas plant of the Renewable Energy Laboratory - LEA at the Federal University of Cearà - UFC. To control the biogas ow a parallel PI controller was used and tested, and the controller was used to perform the comparison with the existing control (centrifugal control) of the gen-set. To check the response of the gen-set powered by biogas, a load corresponding of 60% of the nominal power was used. The proposed system reduced the human intervention in ow setting of the expansion valve. The results showed that the stability response time after the introduction of the PI controller to the original controller allowed the reduction of the response time for at least 20% showing a satisfactory response and a stability for the transition from gasoline to biogas, with 10 Hz amplitude and 8 seconds for the system stabilization with load. This action was considered feasible to automate the process of starting up of the gen-set.

This thesis has investigated the effects of running the two full scale biogas digesters at Slottshagen wastewater treatment plant at 34 °C compared to 37 °C, in terms of process stability, biogas production and energy savings with the aim of saving energy and money by not heating the digesters as much. The main objective was to investigate whether it is at all possible to operate the biogas process at 34 °C or if the process becomes inhibited or otherwise unstable. If the process could be operated at 34 °C it might mean savings of both energy and money, provided that there is still a sufficient production of biogas.The experiment lasted for three months and investigated the short-term effects of the reduction of temperature. The process was monitored closely, and samples from the reactors were collected and analysed twice a week to ensure the stability of the biogas process. Several parameters were monitored online, the biogas production and methane content amongst others. Other parameters were calculated, such as the degree of degradation and specific methane production. This was done to ensure process stability and a sufficient production of biogas. The energy balance was calculated to evaluate if energy was saved by lowering the temperature in the digesters.The results show that the biogas process does remain stable at 34 °C while still producing a satisfactory amount of biogas during the short time of the experiment. Calculations show that both energy and money has been saved during the experiment. However, the system is largely dependent on seasonal variations, therefore further studies over a longer time period would be desirable. During the course of the thesis it has also become evident that the biogas process at Slottshagen is irregular in several aspects, and that it would be beneficial to even the process out, especially with regards to the hydraulic retention time. Making the process more even would enable further improvements to be made and simplify interpretations and comparisons of processstability data.

This thesis explores the details and profitability of two distinct operational strategies utilized by dairy operations as alternatives to expanding milk production. It features farms that have either transitioned to organic production or installed a farm-scale anaerobic digester, motivated in part by the opportunity for market specialization or income diversification to increase the viability of their dairy farm businesses. The first analysis examines the demographics and production characteristics impacting the profitability of organic dairy farmers in Vermont and Maine. This provides policymakers, educators, lenders, and suppliers with a profile of this sector that accounts for 23% of dairy farms in Vermont and 20% of dairy farms in Maine, annually shipping, on average, 787,600 lbs. milk per farm. The study was conducted through a longitudinal survey of 83 organic farmers in Vermont and Maine from 2004 to 2012. A multiple linear regression analysis of the sample demonstrated six significant variables that affect farm profitability measured by return on assets (ROA). Having at least 80% Holstein herd composition, increasing the daily pounds of grain fed to cows during the winter months, a primary farm operator having grown-up on dairy farm, and the use of feed mixing machinery all positively impacted ROA. Farm profitability was negatively affected on farms with a high rate of annual cow morbidity and also tended to decrease over the course of the survey as organic prices leveled. While the model developed here has some explanatory power (R2 = 0.387), variability in farm profitability is affected by complex economic pressures. The second analysis reports the predicted and actual annual maintenance figures collected from anaerobic digester systems in Vermont. Within Vermont, 16 farms operate methane-generating ADS. All of these farms have received some form of public funds and/or a voluntary consumer premium. The analysis compares costs by creating a ratio of actual maintenance, repair, oil, and labor costs over these same predicted costs. This ratio is used to assess whether the suggested industry operating cost estimator tends to over or under predict annual maintenance costs. The ratio was evaluated with a one-way Student's t-test (p = 0.046) finding that maintenance costs tend to be under-predicted compared to the actual costs. One-way ANOVA was used to determine a statistically significant effect of herd size (F = 6.453, p = 0.052), showing that the maintenance ratio varies significantly between groups, This analysis indicates that predicting annual maintenance, repairs, and labor costs as a function of 3.5% of total kWh production is an acceptable method for digesters on farms with more than 500 cows, but under predicts maintenance costs for smaller farms. For smaller farms, the actual costs were on average 2.5 times higher.

Resumo: Avaliaram-se dietas formuladas com milho ou sorgo para suínos nas fases inicial, crescimento e terminação sobre o desempenho dos animais, digestibilidade dos nutrientes, produção e características de fezes e urina e biodigestão anaeróbia dos dejetos. No ensaio de desempenho não foram verificadas diferenças quanto ao consumo médio diário de ração, ganho médio diário de peso e conversão alimentar. Foi realizado um ensaio de digestibilidade em cada fase de crescimento dos animais utilizando o método de coleta total de fezes, não se observando diferenças para coeficientes de digestibilidade da matéria seca e da energia bruta, coeficiente de metabolizabilidade, energia digestível e metabolizável. Os maiores coeficientes de digestibilidade da proteína bruta e proteína digestível foram verificados nos animais alimentados com dietas à base de milho na fase terminação. Para animais alimentados com dietas formuladas com sorgo foram verificados maiores valores de matéria seca digestível nas fases crescimento e terminação. Verificou-se maior produção média de fezes para animais alimentados com dietas formuladas com sorgo, gerando maiores coeficientes de resíduo. Os maiores teores de sólidos totais e voláteis foram verificados nas fezes de animais alimentados com dieta à base de milho, em todas as fases de crescimento. As concentrações médias dos nutrientes nas fezes e na urina variaram entre os tratamentos e fases. O abastecimento de 20 biodigestores indicou maiores reduções nos teores de sólidos voláteis e maiores produções de biogás quando se utilizaram fezes de suínos alimentados com dietas formuladas à base de milho. As concentrações médias dos nutrientes no afluente e efluente dos biodigestores variaram entre os tratamentos e fases. / Abstract: There were evaluated diets formulated with corn or sorghum for pigs in the initial stages, growing and finishing on the growth performance of animals, digestibility of nutrients, production and characteristics of feces and urine and anaerobic digestion of pigs manure. In the test of growth performance were not found differences in the average daily consumption of feed, average daily weight gain and feed conversion. There was performed a test of digestibility at each stage of growth of animals using the total collection of feces, no difference was observed for digestibility coefficients of dry matter and gross energy, coefficient to metabolize, digestible and metabolizable energy. The highest rates of digestibility of crude protein and digestible protein were observed in animals fed with diets based on corn in the finishing stage. For animals fed diets formulated with sorghum there were observed higher values of digestible dry matter in growing and finishing phases. There was a greater average production of feces by animals fed with diets based on sorghum, generating higher coefficient of waste. The highest levels of total and volatile solids were found in the feces of animals fed with diets containing corn, in all the stages of growth. The average concentrations of minerals in feces and urine varied among treatments and stages. The supply of 20 anaerobic digesters indicated greater reductions in the volatile solids levels and greater production of biogas when using waste from pigs fed with diets based with corn. The average concentrations of minerals in the affluent and effluent in the anaerobic digesters varied among treatments and stages. / Orientador: Jorge de Lucas Junior / Coorientadora: Maria Cristina Thomaz / Banca: Mônica Sarolli Silva de Mendonça Costa / Banca: Roberto Alves de Oliveira / Banca: Antônio Carlos de Larentiz / Banca: Maria Benincasa Vidotti / Doutor

<p>In Lembang, a farming community on western Java, family-sized, plug-flow, polyethylene biogas systems fed with cow dung, are being used as an integrated solution to issues related to energy, agriculture and waste management. Through simple, on-farm research and observation, a number of key problems have been addressed and improvements made to the design. Due to the large supply of cow dung in the area, and the potential to spread the benefits of the technology beyond the homes of dairy farmers, the feasibility of developing a communal, polyethylene biogas system for several households, has been investigated. Experiments on small model-digesters were combined with observations of full-scale biogas systems in use. Measurement equipment and techniques were constructed and developed, in order to measure biogas production and other relevant process parameters. Results indicate that a communal system can be an appropriate choice, but only under a certain set of circumstances.</p>

In Lembang, a farming community on western Java, family-sized, plug-flow, polyethylene biogas systems fed with cow dung, are being used as an integrated solution to issues related to energy, agriculture and waste management. Through simple, on-farm research and observation, a number of key problems have been addressed and improvements made to the design. Due to the large supply of cow dung in the area, and the potential to spread the benefits of the technology beyond the homes of dairy farmers, the feasibility of developing a communal, polyethylene biogas system for several households, has been investigated. Experiments on small model-digesters were combined with observations of full-scale biogas systems in use. Measurement equipment and techniques were constructed and developed, in order to measure biogas production and other relevant process parameters. Results indicate that a communal system can be an appropriate choice, but only under a certain set of circumstances.

In Vietnam, the research and application of biogas technology were given a considerable attention in past 30 years. There is several biogas plant models apply in the suburban and rural areas where most people’s life is based on animal husbandry. Each biogas plant model own strong points or weakness that adapt to detail circumstances. The biogas plants play a key role within the VACB farming system especially in the Mekong Delta where produce more than 50% of yearly national agriculture production. This paper gives a comprehensive overview on the popular biogas models in the Mekong Delta through its development history. Knowing on the presented biogas technology in the Mekong Delta will lead the biogas-related organizations or private on biogas development at this region. / Ở Việt Nam việc nghiên cứu và ứng dụng công nghệ khí sinh học đã được chú ý trong 30 năm gần đây. Một số mô hình khí sinh học đã và đang được lắp đặt tại các vùng ngoại ô và nông thôn là những nơi tập trung nhiều hộ dân chăn nuôi heo. Có nhiều mô hình khí sinh học đã được triển khai, trong đó mỗi mô hình đều có những điểm mạnh và điểm yếu đáp ứng theo từng yêu cầu cụ thể. Ở ĐBSCL nơi sản xuất trên 50% sản lượng nông nghiệp của cả nước, hầm ủ khí sinh học đóng một vai trò quan trọng trong mô hình canh tác VACB. Bài báo này trình bày chi tiết các kiểu hầm ủ khí sinh học phổ biến tại ĐBSCL tương ứng với từng thời điểm phát triển của công nghệ này. Sự hiểu biết về các kiểu hầm ủ khí sinh học hiện tại ở ĐBSCL sẽ giúp các tổ chức hoặc cá nhân có liên quan trong việc định hướng phát triển công nghệ khí sinh học cho toàn vùng.