There is an emerging market of radical eco-innovations that require high involvement from the U.S. consumer for successful routinization. Yet, there exists a gap in knowledge that guides the dissemination of such innovations for related stakeholders. Among these innovations is the household digester (HD), which is marketed as an innovation capable of generating biogas and fertilizer through processing organic waste at its point-of-source (POS). The HD may surpass other high-involvement eco-innovations in respect to levels of involvement necessary for consumer routinization and sustained operation. However, previously unexplored factors within the contemporary U.S. landscape have spurred recent growth in HD adoption. This dissertation took a three-manuscript approach in the investigation of factors that influence the adoption and diffusion of HD in the U.S. The first of three studies tested a literature-based conceptual model framed within the multi-level perspective (MLP) to identify barriers and drivers of HD adoption. Qualitative data from expert interviews and social media posts inform the production of a taxonomy of complexities that depict the current state of HD in the U.S. Findings indicate that HD marketing during the Covid pandemic brought forth new adopter populations seeking resilience due to infrastructure distrust. The second study investigated motivations for HD adoption through operationalizing constructs from psychology literature and diffusion of innovation theory (DOI). Through in-depth interviews with adopters, the factors of relative advantage, compatibility, and cost were found to outweigh pro-environmental behavior (PEB) in adoption decisions. Furthermore, high-involvement was not found to influence adoption decisions. The final study employed a collective case study approach that explored paths to HD routinization among ten adopters. Results highlight the ability of adopters to overcome technical challenges through reinventions necessary for contextual adaptations. This dissertation contributes insights into the adoption and diffusion of radical high-involvement eco-innovations, offering implications for policy, practice, and future research in emerging innovations interacting within socio-technical transitions. / Doctor of Philosophy / A variety of emerging products are entering the U.S. consumer market that promote household sustainability, many of which require high levels of involvement from consumers for successful adoption. These high-involvement eco-innovations have been studied within the context of electric cars, organic foods, and other products that require extensive consumer research before purchase. However, this research focuses on a new product entering the U.S. market where involvement not only requires extensive pre-purchase research but also radical levels of interaction during operation and maintenance for successful product use. The household anaerobic digester is an apparatus that turns organic waste into cooking fuel and fertilizer. This innovation has been widely adopted in the developing world with some success, but technical issues during operation have been shown to result in discontinued use. This dissertation focuses on the adoption of household digesters in the U.S. Radical high-involvement eco-innovations need further scientific analysis to understand what factors might affect adoption, as well as explore the viability of such products entering a market where convenience is a social norm. This research aims to provide an analysis of this phenomenon through three studies. Chapter Two explores this new product and factors that may hinder or accelerate adoption in the U.S. Experts in the field of household digesters are interviewed for data collection, as well as analysis of social media posts where new adopters share information. This study aims to determine the social and technical complexities of Americans adopting household digesters. The Third Chapter assesses the purchase motivations of current adopters of household digesters in the U.S. This assessment takes place through interviews, where consumers provide information about their traits, values, and the degree to which they use the product to replace an existing technology. Chapter Four takes a further look at adopters to gain an understanding of paths to adoption and commonly shared practices that are employed to be successful in the adoption of household digesters. This study first presents the stories of each adopter and then provides a cross-case analysis that reveals commonalities of adopters regarding how paths to adoption often lead to shared practices for successful HD operation. The work is summarized in Chapter Five with conclusions, lessons learned, and recommendations for future research. This includes drawing connections between the three studies' findings and how the studies' chronology brought forth validation in the instruments used for data collection.

Anaerobic digestion is one of the most promising management options for dairy manure treatment. Manure wastewater from dairy farms has been used for methane production for decades. However, performance failure due to inadequate mixing is routine. In general, the mixng of anaerobic digester is achived throguh mechnical stirring, liquid circulation, and gas circulation, among which the gas circulation proves to be the most effcient way. In this work, we studied the liquid flow pattern of two differetn type of gas-circualtion based anaerobic digesters, with the aim to understand the effects of hydrodynamic behavior of the digesting liquid on the anaerobic digestion performance, so a better mixing strategy can be provided. We used two 20-L gas circulation based anaerobic digesters with confined (gas-lift) and unconfined (bubble column) design. The anaerobic digestion performance and mixing behaviors were studied at different gas recirculation rate. It was found that the biogas production from the bubble column was constantly higher than that from gas-lift digester. However, the overall flow of the two digesters, which is indicated by residence time distribution (RTD), showed a similar pattern. Furhter investigation of local liquid flow behavior using Computational Fluid Dynamic (CFD) indicate that the bubble column accumulated higher portion of sludge in the bottom of the digester, which has a higher TS and VS, COD, and biomethane production potential than those from the gas-lift digester. This is the reason that the biogas production from the bubble column is higher than the gas-lift digester. Through this study, a thorough characterization of the flow behavior of the anaerobic digester were developed, and provided a deep insight of its influence on the anaerobic digestion performance. / Master of Science

This dissertation determines theoretical targets for producing biogas. Calculations were based on the relationship between the mass of substrate used (assumed to be glucose) versus the amount and composition of gas produced. Methane, hydrogen and carbon dioxide were considered as gases produced by biogas processes. The calculations undertaken to determine the production rates and environmental targets of the biogas production system were based on mass and energy balances as well as the second law of thermodynamics. These were applied to determine the limits of performance of the process. These limits are important due to the fact that they cannot be exceeded even if we genetically engineer organisms or change the equipment design or operation. Combining the results enabled us to plot an attainable region that showed the achievable composition of the gas as well as the minimum work and energy requirements for biogas production. It shows that the process is hydrogen and enthalpy (heat) limited. Furthermore the results show that a maximum of 3 moles of methane per mole of glucose are produced sustainably which in turn produces a large heat load of 142 kJ/mol of glucose. / Physics / M. Sc. (Physics)

Master of Agribusiness / Department of Agricultural Economics / Christine Wilson / Methane digesters are a potential investment for a dairy farm. A digester can lower greenhouse gas emissions, manage manure waste, generate energy, provide fertilizer and recycle bedding. The AgSTAR project of the Environment Protection Agency describes anaerobic digesters as a solution to a problem dairy farmers have always had to solve but that has become more acute with the innovation of larger scale, confined animal feeding operations developed in response to the growing food demands of the world’s larger and more prosperous middle class population – what to do with cow manure. Digesters take cow manure and convert it into energy while also eliminating manure odor. Energy is the primary economic benefit of a digester. A dairy farmer can use the electricity or gas generated from the digester to fuel the energy needs of the farm. Selling gas or electricity on the market is a revenue source that largely determines the level of profit from investing in a digester. This thesis will explore the four economic factors required to make anaerobic digesters a viable economic investment for a 1,500 head cow herd in the United States. It is imperative that farmers are able to obtain a return on the investment as soon as possible as many do not have the capital to invest in a nearly $1 million project. Congress may need to provide additional incentives for farmers and utility companies to take waste and process to energy. The future for methane digesters looks profitable when energy and carbon markets are available and allowed to trade competitively. The federal government may consider focusing on incentives for the utility companies’ infrastructure to make purchases of renewable energy from a digester more economically attractive and efficient. Today, an obstacle for increasing the number of digesters in the United States is the cost associated with moving the energy from the digester and into the national natural gas to grid. Natural gas companies may need to be compensated for that expense plus the potential difficulties of dealing with multiple suppliers or digester owners. Electricity companies have a grid in place to power rural and urban communities. They have spent billions of dollars and decades to establish efficient routing of power to residents and businesses. Manure digesters are mostly located in rural areas that would also require an investment in infrastructure to move the energy from the digester to the power grid. Mandating net-metering would require energy companies to purchase renewable energy, but consumers may see an increase in their cost. Therefore, the answer to increasing the number of manure digesters in the United States may be to direct the incentives to utility companies to invest in expanding infrastructure rather than increasing digester owner subsidies. Although, the REAP grants are helpful for assisting farmers with startup installation costs, there may not be a need to increase that subsidy in the next farm bill if an energy bill includes incentives for energy companies to purchase renewable energy from digesters.

Submitted by Erika Demachki (erikademachki@gmail.com) on 2015-02-06T18:53:51Z No. of bitstreams: 2 Dissertação - Glenda Máris Mesquita - 2014.pdf: 2853247 bytes, checksum: 9d2a3ce805d17ee8a52d5b6e670276af (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2015-02-06T18:54:09Z (GMT) No. of bitstreams: 2 Dissertação - Glenda Máris Mesquita - 2014.pdf: 2853247 bytes, checksum: 9d2a3ce805d17ee8a52d5b6e670276af (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-02-06T18:54:13Z (GMT). No. of bitstreams: 2 Dissertação - Glenda Máris Mesquita - 2014.pdf: 2853247 bytes, checksum: 9d2a3ce805d17ee8a52d5b6e670276af (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-01-27 / Ensuring water quantity and quality for all human beings has been a very discussed topic nowadays. The River Samambaia, watershed that supplies the city of Catalão, has been suffering with anthropogenic actions and the consequences of human intervention. To evaluate the quality of water may be used: water, particulates and sludge. The sediments can store dangerous substances and then can act as a secondary source of pollution by releasing contaminants into the aquatic environment. Within this context, the aim of this study was to evaluate the potential for contamination and the quality of the River Samambaia, located in Catalão-GO. For this, samples of water and sediment were collected at seven sampling sites along the river and the metals arsenic, cadmium, lead, chromium, manganese and nickel, which are considered toxic, were quantified. Was also performed, on the sampling sites, the analysis of physico-chemical water parameters: pH, conductivity, dissolved oxygen, temperature and salinity. For the extraction of metals fixed in the sediment samples was employed three methods of opening: ultrasound assisted extraction, digestion in digester block and microwave digestion. The quantification of metals was done by Atomic Absorption Spectrometry, by Flame or by Electrothermal Atomization in Graphite Furnace. The three methods opening samples used were effective, but the microwave digestion excelled in all cases. Among the physico-chemical parameters analyzed, pH showed values outside those permitted by law in all sampling points and dissolved oxygen showed the value below allowed only in point 7. In measurements of metals in water samples, cadmium, lead and chromium showed concentrations above the maximum allow by CONAMA. Already for the quantification of metals in the sediment samples, only chromium showed a concentration above the permitted limits. The results presented here indicate that human activities carried out in the river have contributed to adverse effects on local biota and humans. / A garantia de água com quantidade e qualidade para todos os seres humanos tem sido um assunto muito abordado na atualidade. O Ribeirão Samambaia, manancial que abastece a cidade de Catalão, vem sofrendo com as ações antrópicas e com as consequências dessa intervenção humana. Para avaliar a qualidade da água podem ser utilizados: água, materiais particulados e sedimentos. Os sedimentos podem estocar substâncias perigosas e, então, atuar como uma fonte secundária de poluição pela liberação de contaminantes no meio aquático. Dentro desse contexto, o objetivo deste trabalho foi avaliar o potencial de contaminação e a qualidade do Ribeirão Samambaia, localizado em Catalão-GO. Para isso, foram coletadas amostras de água e de sedimento em sete pontos de amostragem ao longo do ribeirão e os metais arsênio, cádmio, chumbo, cromo, manganês e níquel, os quais são considerados tóxicos, foram quantificados. Também foi realizada, nos locais de amostragem, a análise dos seguintes parâmetros físico-químicos da água: pH, condutividade, oxigênio dissolvido, temperatura e salinidade. Para a extração dos metais fixados nas amostras de sedimento foi empregado três métodos de abertura: extração assistida por ultrassom, digestão em bloco digestor e digestão em forno de microondas. A quantificação dos metais foi feita por Espectrometria de Absorção Atômica, por Chama ou por Atomização Eletrotérmica em Forno de Grafite. Os três métodos de abertura de amostras utilizados se mostraram eficientes, porém a digestão em forno de microondas se destacou em todos os casos. Dentre os parâmetros físico-químicos analisados, o pH apresentou valores fora do permitido pela legislação em todos os pontos de amostragem e o oxigênio dissolvido mostrou valor abaixo do permitido apenas no ponto 7. Nas quantificações dos metais nas amostras de água, cádmio, chumbo e cromo apresentaram concentrações acima do limite máximo permito pelo CONAMA. Já para as quantificações dos metais nas amostras de sedimento apenas o cromo apresentou concentração acima do permitido. Os resultados apresentados nesse trabalho indicam que as atividades antrópicas realizadas no ribeirão têm contribuído com efeitos negativos para biota local e aos seres humanos.

Submitted by Maicon Juliano Schmidt (maicons) on 2015-04-27T17:27:26Z No. of bitstreams: 1 Neuri Rempel.pdf: 1414299 bytes, checksum: e09f1fc8267c07d066f0e701aca28d19 (MD5) / Made available in DSpace on 2015-04-27T17:27:26Z (GMT). No. of bitstreams: 1 Neuri Rempel.pdf: 1414299 bytes, checksum: e09f1fc8267c07d066f0e701aca28d19 (MD5) Previous issue date: 2014-01-30 / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / FINEP - Financiadora de Estudos e Projetos / Ministério da Ciência, Tecnologia e Inovação / O aproveitamento energético da fração biodegradável dos Resíduos Sólidos Urbanos (RSU) na forma de biogás, é uma das alternativas para minimizar os impactos sociais e ambientais causados pela disposição destes resíduos. A digestão anaeróbia sob condições controladas, objetivando o máximo de rendimento de biogás é uma alternativa promissora, principalmente quando for conduzida com o acréscimo de outros resíduos orgânicos de elevado potencial para geração de biogás, como a glicerina. A glicerina é um subproduto da produção de biodiesel e possui percentual de carbono acima de 90%, tornando-se um excelente cosubstrato para digestão anaeróbia. Esta pesquisa avaliou a geração de biogás em escala piloto, utilizando a fração orgânica do RSU pós-esteira de triagem da cidade de São Leopoldo/RS, com incremento de glicerina em relação à massa de resíduo adicionada no digestor. Utilizou-se um reator de 50L com agitação intermitente e temperatura controlada (~35ºC). O incremento de glicerina possibilitou aumento de até 30% no volume de biogás gerado, além de antecipar em até 10 dias a produção máxima de biogás, quando comparado com o processo somente com os RSU. O decréscimo gradativo do pH, a elevada relação C:N no materialdigerido e adição de NaOHpara o controle do pH, indicam que o percentual de glicerina adicionado, nas condições desse estudo pode ter sido elevado, necessitando maiores investigações para chegar no volume adequado.Os resultados observados indicam a necessidade de se determinar o percentual ótimo de glicerina a ser utilizado, o que não foi possível nesse estudo. Agitação intermitente, manutenção do pH próximo de 7,5 e Tempo Retenção de Sólidos máximo de 25 dias, foram os principais parâmetros observados para a otimização na geração do biogás, nas condições desse estudo. O volume médio de biogás produzidofoi de 44m3/ton. de RSU, com valores mínimos e máximos de 30 m3/ton.e 60 m3/ton. de RSU, respectivamente. / The energetic use of the biodegradable fraction of Municipal Solid Waste (MSW) in the form of biogas is one of the alternatives to minimize the social and environmental impacts caused by the disposal of this waste. Anaerobic digestion under controlled conditions, aiming the maximum yield of biogas, is promising alternative, especially when conducted with the addition of others organic wastes with high potential for biogas generation, such as glycerin. Glycerin is a subproduct of biodiesel production and carbon percentage above 90%, making it an excellent co-substrate for anaerobic digestion. This research evaluated the generation of biogas in pilot scale, using the organic fraction of the MSW post-treadmill screening of São Leopoldo/RS, with the increase of glycerin on the mass of residue added to the digester. A 50L reactor with intermittent agitation and controlled temperature (~35°C) has been used. The increase of glycerin made possible the raise up to 30% in the volume of generated biogas, besides anticipate within 10 days maximum biogas production compared to the process only with MSW. The gradual decrease in pH, the high C:N ratio in digested material and the addition of NaOH to control the pH, indicate that the percentage of glycerin added, under the conditions of this study may have been high, requiring further investigation to reach proper volume. The results indicate the necessity to determine the optimal percentage of glycerin to be used, which was not possible in this study. Intermittent agitation, maintaining the pH close to 7.5 and Maximum Solids Retention Time of 25 days, were the main parameters observed to optimize the generation of biogas, in the conditions of this study. The mean volume of biogas produced was 44m3/ton of MSW with minimum and maximum values of 30 m3/ton and 60 m3/ton MSW, respectively.

Nutrients present in digested animal waste can be utilized for algae cultivation under suitable conditions. Algal growth, however, depends on the chemical forms and speciation of these nutrients. In this study a chemical equilibrium model was first used to describe nutrient speciation and predict conditions that enhance the solubility of nutrients in anaerobic digester effluent. Dilution with water and separation of large particulates greatly improved nutrient availability and light penetration - conditions favorable for algal cultivation. Algae growth was tested using three strains - Scenedesmus dimorphous (UTEX # 417), Chlorella vulgaris (UTEX# 265), and an algal isolate (designated as LLAI and later identified to be closely related to Chlorella vulgaris) from the wastewater treatment lagoons in Logan, UT. All tested strains could be adapted to the effluent to enhance the utilization of native nutrients present in both organic and inorganic forms. There was a marked improvement in growth rates (up to 4.8-fold) and biomass production (up to 8.7-fold) of algal cultures after they adapted to the effluent. Also, effluent-adapted strains were able to switch from phototrophy to heterotrophy to prolong the growth when light availability became limited. However, an increase in irradiance levels in light-limited cultures led to resumption of phototrophic growth. It was found that this approach of light supplementation prolonged growth and increased biomass production (up to 2.7-fold) in algal cultures. Of all the strains tested, the isolate from the wastewater treating lagoons grew to highest culture densities and produced the highest concentration of intracellular triacylglycerides (TAG). This culture also grew best in non-sterile, native effluent and could reach biomass concentration of up to 4.5g/L with TAG content of approximately 10% (w/w). Culture densities were lower when this organism was grown in sterilized effluent or in sterile artificial media, suggesting that this organism symbiotically associated with other microbes in digested animal waste. Findings of this research study suggest that microalgae can be grown efficiently on inexpensive natural substrates in non-sterile growth conditions. When commercially implemented, biodiesel production from such systems could be more cost effective and sustainable.

<p>In the pulp industry, digesters are used to disolve lignin in wood chips. The concentration of lignin is measured and is called the Kappa number. In this thesis, the question of whether an online Kappa sensor, taking samples from the mid-phase of the digester, is useful or not is analyzed. For the samples to be useful, there has to be a relationship between the measured Kappa at the mid- phase and the measured Kappa in the blowpipe at the bottom of the digester. An ARX model of the lower part of the digester has been estimated. Despite a lot of noise, it seems that it might be possible to use the mid-phase samples and for this model predict the blowpipe flow Kappa signal. It is concluded that the mid-phase samples should be further improved to be more useful. The mid-phase samples have also been used in another ARX model, this time to LP-filter these values without time loss. </p><p>Another important issue has been to examine if the existing controller is good or not. In order to be able to compare it with other controllers, a simulator has been created in MATLAB - Simulink. Test results from this simulator show that the existing controller's use of the mid-phase Kappa samples improves its performance. For a simplified digester model, the existing controller has also been compared with an MPC controller. This test shows that the MPC controller is significantly better. Hence, the conclusion in this thesis is that it might be interesting to study MPC further using a more advanced model.</p>

In the pulp industry, digesters are used to disolve lignin in wood chips. The concentration of lignin is measured and is called the Kappa number. In this thesis, the question of whether an online Kappa sensor, taking samples from the mid-phase of the digester, is useful or not is analyzed. For the samples to be useful, there has to be a relationship between the measured Kappa at the mid- phase and the measured Kappa in the blowpipe at the bottom of the digester. An ARX model of the lower part of the digester has been estimated. Despite a lot of noise, it seems that it might be possible to use the mid-phase samples and for this model predict the blowpipe flow Kappa signal. It is concluded that the mid-phase samples should be further improved to be more useful. The mid-phase samples have also been used in another ARX model, this time to LP-filter these values without time loss. Another important issue has been to examine if the existing controller is good or not. In order to be able to compare it with other controllers, a simulator has been created in MATLAB - Simulink. Test results from this simulator show that the existing controller's use of the mid-phase Kappa samples improves its performance. For a simplified digester model, the existing controller has also been compared with an MPC controller. This test shows that the MPC controller is significantly better. Hence, the conclusion in this thesis is that it might be interesting to study MPC further using a more advanced model.

Women living in rural Kenya rely on wood for cooking and are exposed to elevated amounts of wood smoke. The objective of this thesis was to assess the health and quality of life benefits of installing biogas digesters on rural Kenyan dairy farms. Thirty-one farms with biogas digesters and 31 farms without digesters (referent group) were assessed for wood utilization practices, basic respiratory and self-reported health, and exposure to volatile organic compounds (VOCs). Women with biogas digesters spent less time and money acquiring wood, and less time exposed to wood smoke (p<0.01). Multivariable linear regression showed associations between daily wood consumption and having a biogas digester, family size, and number of cows. Individual VOCs were lower in cookhouses on biogas farms (p<0.001) and women with biogas digesters reported fewer respiratory symptoms. Biogas digesters are one technology that can reduce reliance on wood fuel and reduce exposures to harmful wood smoke.