There is growing interest in the use of high performance anaerobic digestion (AD) processes for the production of biogas at wastewater treatment facilities to offset the energy demands associated with wastewater treatment. Recuperative thickening (RT) is a promising technique which involves recycling a portion of the digested solids back to the incoming feed. In general there exists a significant number of knowledge gaps in the field of RT because the studies that have been conducted to date have almost exclusively occurred in pilot or full scale trials; this approach greatly limits the amount of process optimization that can be done in a given trial. In this work, a detailed and comprehensive study of RT processes was conducted at the lab scale; a demonstration of the optimization of polymer assisted dewatering is given and biogas production and quality monitored. Two custom designed digesters (capacity = 1.5 L) were operated in parallel with one acting as a ‘control’ digester and the other operating under a semi-batch RT mode; both digesters were also operated in parallel under RT with alternative polymer flocculants. There were no significant changes in the overall biogas methane composition; however the RT digester had an average biogas productivity over two times higher than the control one. It was found that the recycling of the polymer flocculant back into the RT digester resulted in a significant improvement in dewatering performance. At the highest polymer concentration tested, all polymer flocculants demonstrated equivalent dewatering performance achieving over 6 times lower CST’s than the control; at lower polymer concentrations the 4516 polymer flocculant had superior dewatering performance. Thus, there exists an opportunity to decrease the overall consumption of polymer flocculants through judicious selection of the flocculant and the dose that is used both for the thickening and end-stage dewatering processes in RT digesters. / Thesis / Master of Applied Science (MASc) / In wastewater treatment (WWT), solid wastes are treated using a technique called anaerobic digestion (AD) which involves the conversion of solids in biogas by anaerobic bacteria. Biogas is a mixture of mostly methane and carbon dioxide and can be used as a fuel source for energy production. There’s growing interest in the use of high performance AD processes for the production of biogas at WWT facilities to offset the energy demands associated with WWT. Recuperative thickening (RT) is a promising technique which involves recycling a portion of the digested solids back to the digester. In this work, a detailed and comprehensive study of RT processes was conducted at the lab scale; a demonstration of the optimization of polymer assisted dewatering is given and biogas production and quality monitored. Two 1.5 L custom designed digesters were operated in parallel one as a ‘control’ and the other operating under a semi-batch RT.

Im Ergebnis der in den Jahren 2006 und 2007 an der TU Freiberg durchgeführten Gärversuche stand die Forderung nach weiteren Untersuchungen der in der Praxis vorherrschenden Mischsubstrate auf ihre grundsätzliche Vergärbarkeit, Gasproduktion und Gaszusammensetzung. So wurden Ganzpflanzensilage (GPS) Triticale, Kleegras-, Luzernegrassilage, Maissilage, Zuckerrübe, Gehaltsrübe, kaltgepresster Rapskuchen oder fusarienbelasteter Triticaleschrot als Cofermente zu Rindergülle oder Hühnerkot eingesetzt. GPS Triticale und Zuckerrüben lieferten als Monosubstrate keine stabile Vergärung und damit keine auswertbaren Ergebnisse. Spitzenwerte in der Methangasproduktion erzielten Rindergülle in Kombination mit GPS Triticale oder Zuckerrüben. Ebenfalls hohe Methangasausbeuten erzielte die Kombination von Maissilage und Hühnertrockenkot mit Rindergülle. Bei der Cofermentation von mykotoxinbelastetem Getreide ergab sich kein negativer Einfluss auf die Prozessstabilität. Die Zugabe von Enzymen als Betriebshilfsstoff bewirkte eine geringfügige Steigerung der Methangasproduktion. Für die Prozessoptimierung und damit optimale Auslastung der Biogasanlage sollten sprunghafte Veränderungen der Inputzusammensetzung vermieden werden.

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The biogas plant Kungsängens gård, owned by Uppsala Vatten och Avfall AB, produces biogas and biomanure from organic household waste, food processing waste and slaughterhouse waste. In year 2012, 4.4 million Nm3 of biogas were produced from 25 200 tons of waste. Before digestion all substrate is sanitized by pasteurization at 70°C in order to kill pathogens. Another method, integrated thermophilic sanitation (ITS), is of interest in order to decrease the energy demand. The method implies that the substrate is sanitized during ten hours in the digestion chamber, where the temperature is 52°C. The purpose of this thesis was to compare pasteurization with integrated thermophilic sanitation from an energy point of view. The pasteurization´s impact on biogas production and energy yield was examined through experiments with two laboratory digesters, of which one was fed with pasteurized substrate and the other with non-pasteurized substrate. For the present pasteurization system, electricity and heat demand was surveyed. For the integrated thermophilic sanitation, a process design was developed and dimensioned and the electricity and heat demand was calculated. Thereafter, the energy yield and energy demand for the two sanitation systems were compared. The result showed that pasteurization had no effect on biogas production. The energy yield was on average 4.79 kWh/kg VS from non-pasteurized substrate and 4.74 kWh/kg VS from pasteurized substrate. There was no statistically significant difference between the reactors. The energy audit showed that pasteurization required 0.48 kWh/kg VS, which is 85 % of the total energy consumption at the facility. The digester warming demanded 0.077 kWh/kg VS for RK1 and 0.031 kWh/kg VS for RK2. The electricity consumption was 0.041 kWh/kg VS. The process of ITS was designed with a heat exchange from bio manure to substrate, followed by heating to 52°C by steam addition. The heat requirement was 0.24 kWh/kg VS and the electricity demand was 0.034 kWh/kg VS. The warming of the digesters was the same as in the present pasteurization system. The comparison between the existing pasteurization and the ITS showed that switching systems would save 0.243 kWh/kg VS or 46 % of the present energy consumption. This corresponds to annual savings of 1.22 GWh. A sensitivity analysis showed that the results were sensitive to assumptions regarding the heat exchanger in the case of ITS. 10 % energy losses resulted in smaller savings, 34 % or 0.91 GWh per year. There are increased risks of process disruptions if ITS is combined with an increased organic loading rate. 4.2 % reduction of the total biogas production erases the energy savings which means that it is important that process stability is ensured.

Made available in DSpace on 2014-06-11T19:28:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-28Bitstream added on 2014-06-13T19:16:11Z : No. of bitstreams: 1 junqueira_jb_me_jabo.pdf: 613418 bytes, checksum: 2d96f9a3a3a9a81ba8c0d4213f5c57be (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Tendo em vista o aumento no número de confinamentos e todos os problemas ambientais gerados pela grande quantidade de dejetos depositados em uma área reduzida, o trabalho visa contribuir com informações que viabilizem a sustentabilidade na criação de bovinos de corte em sistemas intensivos, fomentando a integração de sistemas de criação animal e culturas vegetais, por meio do manejo adequado dos resíduos gerados e posterior aproveitamento na adubação de culturas. Para tanto, objetivou-se com o presente desenvolver os processos de biodigestão anaeróbia e compostagem, avaliando a produção e qualidade do biogás, biofertilizante e composto gerados. Avaliar a aplicação de adubo orgânico (biofertilizante e composto) e adubo mineral em pasto cultivado com a planta forrageira Panicum maximum Jacq. cv. Tanzânia. Foram utilizados os dejetos gerados por bovinos de corte confinados. O material foi destinado à formação de leiras de compostagem e ao abastecimento de biodigestores anaeróbios. O biofertilizante e o composto gerados foram utilizados na adubação da planta forrageira. O uso de adubo mineral promoveu as maiores quantidades de massa de forragem em relação aos demais. As plantas adubadas com biofertilizante obteve a melhor relação lâmina foliar:colmo (1,88). Os teores de proteína na lâmina foliar variaram de 15,62% a 9,2%. A composição bromatológica da forragem da área adubada com adubo orgânico (biofertilizante e composto) foi superior aos da forragem da área adubada com adubo mineral. A adoção da adubação orgânica foi viável, não somente como proposta de modelo de produção sustentável, mas também como forma de incrementar o lucro gerado na atividade / Given the increase in number of confinements and all the environmental problems caused by the large amount of waste deposited in a small area, the work aims to contribute information that will enable sustainability in the farming of beef cattle in intensive systems, fostering systems integration, animal husbandry and crops, through the proper management of waste generated and further use in the fertilization of cultures. To do so, with the objective to develop the processes of this anaerobic digestion and composting, evaluating the yield and quality of gas, fertilizer and compost generated. To evaluate the application of organic manure (compost tea and compost) and mineral fertilizer in the pasture cultivated with forage grass Panicum maximum Jacq. cv. Tanzania. We used the manure generated by beef cattle. The material was used for the formation of windrows for composting and anaerobic digesters to supply. The biofertilizer and compost generated were used in the fertilization of forage. The use of mineral fertilizer produced the greatest amounts of dry matter in relation to others. Plants fertilized with biofertilizer had the best leaf blade: stem ratio (1.88). The protein contents in leaf blade ranged from 15.62% to 9.2%. The chemical composition of the forage area fertilized with organic fertilizer (compost tea and compost) was greater than the area of forage fertilized with mineral fertilizer. The adoption of organic manure was feasible, not only as a proposed model of sustainable production, but also as a way of increasing the profit generated in the activity

För att nå de klimatpolitiska målen arbetar såväl Sverige som EU aktivt mot en cirkulär ekonomi där varje resurs nyttjas så effektivt som möjligt. En del i det arbetet handlar om att lyfta fram hållbara energikällor för att succesivt fasa ut fossila bränslen. Ett etablerat förnybart energislag, som fått mer uppmärksamhet på senare tid, är biogas. Produktionen av biogas sker via rötning av biologiskt material och kan generera el och värme, men även uppgraderas till fordonsgas. Ett av alla substrat som kan användas för rötning är gödsel. Den här studien har till syfte att undersöka omfattningen av den outnyttjade energipotentialen i gödsel från mjölkproducerande lantbruk i Sverige. Därtill ger den en bild av hur mycket koldioxid från fossila energikällor som skulle kunna minska i och med tillvaratagandet av energin i gödsel. En gårdsbaserad biogasanläggning vid Fredrikslunds lantbruk i Kalmar kommun är utgångspunkten och beräkningar görs tillsammans med data från bland annat Jordbruksverket och Energigas Sverige. För beräkning av möjligheten till minskat koldioxidutsläpp från fossil källa görs jämförelse med eldningsolja som används vid de svenska kraftverken. Resultatet visar att det finns en betydande energipotential i gödsel från svenska mjölk- producerande lantbruk där majoriteten av den ännu inte nyttjas för biogas- produktion. Nya styrmedel har tillkommit med syfte att gynna en ökad biogasproduktion, vilket kan öka chanserna för att ta vara på energipotentialen. Att genom ökad biogasproduktion minska mängden utsläpp av koldioxid till atmosfären från fossila källor ses också som möjlig. Sammanfattningsvis är studien ett exempel på hur en befintlig resurs kan effektiviseras ytterligare, ett arbete som troligen kommer bli än viktigare framöver. / To reach the climate goals, Sweden and the European Union are working towards a circular economy where the resources are used as efficiently as possible. Part of that work is about highlighting sustainable energy sources to gradually replace fossil fuels. An established, renewable type of energy, which has received more attention recently, is biogas. Biogas is produced through anaerobic digestion of biological material. The produced gas can generate electricity and heat, but it can also be upgraded to compressed biogas and used as automotive fuel. One of the substrates that can be used for digestion is manure. The aim of this study is to investigate the extent of the energy potential in manure from dairy farms in Sweden. In addition, it gives an idea of how much carbon dioxide from fossil energy sources that could be reduced if the energy potential in manure were used. Data is received from a farm- based biogas plant at Fredrikslund's farm in Kalmar as well as Swedish statistics of agriculture and energy. To estimate the possibility of reduced carbon dioxide emissions from fossil sources, a comparison is made with fuel oil. The results show that there is a considerable energy potential in manure from Swedish dairy farms where the majority is not yet used for biogas production. Reducing the amount of carbon dioxide emissions into the atmosphere from fossil sources through increased biogas production is also seen as possible.

The overall goal of the thesis was to develop and optimize the moving bed biofilm reactor technology under anaerobic conditions. The thesis work was divided into two different series of experiments. Hence, at first, the reactor start-up on synthetic substrate was evaluated and it was proven that the anaerobic moving bed biofilm reactor technology could successfully treat concentrated wastewater. Subsequently, a study on Fort Garry Brewery wastewater was conducted to optimize the process for a typical North American industrial wastewater. The aim was successfully achieved and a potential design to treat Fort Garry Brewery wastewater was developed. The anaerobic moving bed biofilm reactor was found to be capable in treating brewery wastewater with potential savings to the industry paying surcharges for discharging wastewater over the city sewer bylaw limits. / October 2016

Reduction is the best way of handling the issue of food waste, however, considering the difficulties of achieving reduction, a collection of waste for a potential decrease was established. The thesis consist of an examination between two subjects, the issue of food waste and the waste management system of collecting food waste to produce biogas, where the main focus is upon the municipality of Stockholm. The purpose of the study was to analyze the issue of food waste and connect it to the process of collecting food waste to produce biogas, and examine the potential benefits and conflicts between these two topics. The aim was also to investigate the process possibilities and functionality, and how the procedure is operating in the municipality of Stockholm. Besides a litterature study, four interviews were conducted with respondents from authorities and the municipality. The results show that the process of collecting food waste to produce biogas is a great procedure. It is a good alternative for the environment and generates to a substitute towards fossil fuel. However, whether the process is a benefit for the issue of food waste seems to be rejected. There are also difficulties of apprehending the connection between the two subjects, since they are seen as topics that lie collaterally to each other. In the municipality of Stockholm, the process function within the section of restaurants, however, it is not that fortunate within households. The factors of simplicity, profitability and trust are the main features threatening the success of the process of collecting food waste to produce biogas. One may presume that the goal/requirement firsthand is to focus upon reduction of food waste. However, there seems to be a shift from consuming less (reduce the waste) to consuming differently (reuse the waste) nowadays, hence the process of collecting food waste to produce biogas is central.

This master’s thesis has been performed in Bangkok, Thailand at the company Eco Design Consultant Co., Ltd. The aim is to investigate the possibilities to generate absorption cooling from municipal solid waste in the Bangkok area. The investigation includes a comparison between waste incineration and biogas production with combustion to see which alternative is preferable. During the investigation, a Swedish perspective has been used. The research for the report mainly consisted of published scientific articles from acknowledged sources as well as information from different Thai authorities. Also, experts within different areas were contacted and interviewed. In order to determine which of the two techniques (waste incineration or biogas production with combustion) that is best suited to generate absorption cooling, a model was designed. This model involved several parameters regarding e.g. plant efficiency, amount of treated waste and internal heat usage. As for the results of the model, three parameters were calculated: the generated cooling, the net electricity generation and the reduced greenhouse emissions. The overall Thai municipal solid waste generation in Thailand is estimated to approximately 15 million tons per year and the majority of the waste ends up at open dumps or landfills. There are only two to three waste incinerators in the country and a few projects with biogas generation from municipal solid waste. The main electricity is today generated from natural gas which makes the majority of the Thai electricity production fossil fuel based. As for absorption cooling, two applications of this technique has been found in Thailand during the research; one at the Naresuan University and one at the Suvarnabhumi airport in Bangkok. The model resulted in that the best alternative to power absorption cooling technique is waste incineration. This alternative has potential to generate 3200 GWh cooling per year and 1100 GWh electricity per year. Also, this alternative resulted in the largest decrease of greenhouse gas emissions, ‐500 000 tons per year. The model also showed that the same amounts of generated cooling and electricity can never be achieved from biogas production with combustion compared to waste incineration. Regardless, waste incineration has an important drawback: the citizens of Thailand seem to oppose further development of waste incineration in the country. The biogas technique seems more approved in Thailand, which benefits this alternative. Due to the high moisture and organic content in the municipal solid waste, a combination between the two waste handling alternatives is suggested. This way, the most energy can be withdrawn from the waste and the volume of disposed waste is minimized. Our overall conclusion is that the absorption cooling technique has great potential in Thailand. There is an increasing power‐ and cooling demand, absorption cooling generated from either or both of the alternatives can satisfy these demands while reducing greenhouse gas emissions. We also believes that the cost for using absorption cooling has to be lower than for the current compression cooling if the new technique is to be implemented further.

Vietnam is one of the countries suffering from the most serious adverse effects due to climate change and sea level rise. The main cause of climate change is the increased activities generating greenhouse gases. Organic waste is the main source of carbon dioxide emission, which has the largest concentration among different kinds of greenhouse gases in the earth’s atmosphere. The conversion of organic waste and biomass into energy contributes not only to supply cleaner energy but also to reduce emissions of greenhouse gases. Vietnam has a large potential of biomass and agricultural by-products. The technologies to turn biomass into different kinds of bio-energies were developed and applied all over the world. Biogas was called as "brown revolution" in the field of new energy. Biogas production technology now has been studied and applied widely in the world, particularly in developing countries with warm climate that is suitable for anaerobic fermentation of organic waste. The biogas digester can be built with any capacity, needs small investment and the input materials are widely available. The biogas energy is used for many purposes such as cooking, lighting, running engines, etc. It is a production technology quite consistent with the economy of developing countries and really brings to life more civilized and convenient to rural areas. / Việt Nam là một trong những quốc gia bị tác động nghiêm trọng nhất do biến đổi khí hậu và nước biển dâng cao. Nguyên nhân chính của biến đổi khí hậu là các hoạt động gia tăng tạo ra các khí gây hiệu ứng nhà kính. Chất thải hữu cơ là nguồn chính phát thải khí carbon dioxide có nồng độ lớn nhất trong số các loại khí gây hiệu ứng nhà kính khác nhau trong bầu khí quyển của trái đất. Việc chuyển đổi chất thải hữu cơ và sinh khối thành năng lượng góp phần không chỉ cung cấp năng lượng sạch hơn mà còn giảm phát thải khí gây hiệu ứng nhà kính. Việt Nam có một tiềm năng lớn về sinh khối và phụ phẩm nông nghiệp. Các công nghệ biến sinh khối thành các loại năng lượng sinh học khác nhau đã được phát triển và áp dụng rộng rãi trên thế giới. Khí sinh học được gọi là "cuộc cách mạng màu nâu" trong lĩnh vực năng lượng mới. Công nghệ sản xuất khí sinh học đã được nghiên cứu và áp dụng rộng rãi trên thế giới, đặc biệt là ở các nước đang phát triển với nhiệt độ khí hậu nhiệt đới phù hợp cho quá trình lên men kỵ khí các chất thải hữu cơ để sản xuất khí sinh học. Bình phản ứng tạo khí sinh học có thể được xây dựng với công suất bất kỳ, nhu cầu đầu tư nhỏ, các nguyên liệu đầu vào sẵn có. Năng lượng khí sinh học đã được sử dụng cho nhiều mục đích như thắp sáng, nấu ăn, chạy động cơ, v.v... Đây là hoạt động sản xuất khá phù hợp với nền kinh tế của các nước đang phát triển và thực sự đem lại cuộc sống văn minh hơn và tiện lợi đến các khu vực nông thôn.