Dairy farms can apply anaerobic digestion (AD) as a manure management system, while producing renewable energy. Ultimately, this can reduce greenhouse gas (GHG) emissions. There is much research work that has quantified the changes in emissions due to AD. However, important methodologies such as the Intergovernmental Panel on Climate Change (IPCC) Guidelines, rely only on a small sample of the accumulated scientific findings in the field. This thesis improves the robustness of these methodologies by applying data-driven techniques to estimate values of the energy output of AD systems and their consequent effect in GHG emissions. For this purpose, meta-analyses techniques are applied to mathematically combine metrics from 155 non-standardised research publications (i.e. with different boundaries, scopes and functional units). As a first step, a novel database is created by systematically searching for relevant articles and assessing them against defined criteria. The database is divided in two parts. Given that the offset of GHGs is highly dependent on the energy output of AD system, empirical methane yields (i.e. key metric of AD performance) are collected in Part I of the database. GHG released from different farm activities are input to Part II of the database. To quantify the change in emissions from these activities, standard baseline and AD scenarios are defined. The second step of the meta-analysis consists of applying uni- and multi-variate tests to the database. For Part I, methane yields are analysed in terms of type of digesters. From the batch digesters, new maximum methane yields are proposed based on the combined results of 42 peer reviewed articles. These results offer better estimates than default values of methane yields from the 2007 Guidelines of the IPCC, which only consider two studies. For continuously stirred tank digesters and semi-continuous digesters lower methane yields are revealed. Multi-variate analysis of methane yields together with operating conditions and manure composition, enable the identification of clusters. These groups of variables can be useful to build potential AD scenarios in dairy farms. For Part II of the database, relative changes in emissions between the activities in the standardised baseline and AD scenarios, are examined. It is found, through meta-analysis, that replacing raw manure by anaerobically-treated manure (i.e. digestate) in storage tanks and for field- application, mitigates baseline emissions by 38.7% and 6.9%, respectively. These relative changes can be used to estimate emissions from digestate, being more specific and evidence-based than the current methodology from the IPCC. In addition, relative changes found for offset of fossil fuels by biogas generated in the AD scenarios indicate a reduction of baseline emissions by 9.0%. Only methane leaks from digesters significantly increase the baseline emissions (by 7.4%). Finally, results found by meta-analyses of methane yields and changes in emissions are applied to four dairy farm case studies. The work presented in the case studies demonstrates the benefits of enhancing the robustness of methods to estimate the effect of AD on GHG emissions from dairy farms.

Made available in DSpace on 2014-06-11T19:27:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-11-30Bitstream added on 2014-06-13T20:35:47Z : No. of bitstreams: 1 abreuneto_ms_me_jabo.pdf: 1673746 bytes, checksum: f710855d25440c302ba5cd9d3ff6e36a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho avaliou-se o desempenho de processo anaeróbio em dois estágios composto por reator compartimentado (ABR) e reator de fluxo ascendente com manta de lodo (UASB), instalados em série, em escala-piloto (volumes de 530 e 120 L, respectivamente), tratando águas residuárias de suinocultura com concentrações de sólidos suspensos totais de 4.591 a 13.001 mg L-1, submetidos a tempos de detenção hidráulica (TDH) de 60 a 24 h no primeiro reator e de 13,6 a 5,4 h no segundo reator. As eficiências médias de remoção de DQOtotal variaram de 69 a 88% no reator ABR e de 34 a 58% no reator UASB, resultando em valores médios de 87 a 95% para o sistema de tratamento anaeróbio em dois estágios (ABR+UASB) com carga orgânica volumétrica (COV) de 11,51 a 21,12 g DQOtotal (L d)-1 no reator ABR, e de 4,21 a 13,29 g DQOtotal (L d)-1 no reator UASB. As eficiências de remoção de SST e SSV variaram de 86 a 96% e 88 a 97% no sistema de tratamento (ABR+UASB). A produção volumétrica de metano máxima de 0,455 m3 CH4 (m3 reator d)-1 ocorreu no reator ABR, com COV de 13,42 g DQOtotal (L d)-1 e TDH de 48 h. Obtiveram-se eficiências médias de remoção de 62 a 95% para Cu, Fe, Mn e Zn e de 30 a 71% para NTK e P-total. Houve remoção de coliformes totais e fecais de 91,935 a 99,667% porém, foram observados nos efluentes número de coliformes fecais acima de 1,5 x 105 NMP/100 mL, o que restringe sua aplicação para a irrigação de plantas... / In this work it was evaluated the performance of two stage anaerobic process constituted of anaerobic baffled reactor (ABR) and an upflow sludge blanket reactor (UASB) installed in series, in pilot scale testing (volumes of 530 and 120 L, respectively) treating swine wastewater with total suspended solid (TSS) concentration of 4591 a 13001 mg L-1 on and with hydraulic detention times (HDT) of 60 to 24 h in the first reactor and 13,6 to 5,4 h in the second reactor. The mean CODtotal removal efficiency varied from 69 to 88% in ABR and from 34 to 58% in UASB reactor, resulting in average values ranging from 87 to 95% for the two stage anaerobic treatment system (ABR+UASB) under organic volumetric load (OVL) of 11.51 to 21.12 g CODtotal (L d)-1 in ABR and 4.21 to 13.29 g CODtotal (L d)-1 in UASB reactor. The TSS and VSS removal efficiency varied from 86 to 96% and 88 to 97% in anaerobic treatment system (ABR+UASB). The maximum volumetric methane production of 0.455 m3 CH4 (m3 reactor d)-1 occurred in ABR reactor with OVL of 13.42 g CODtotal (L d)-1 and HDT of 48 h. The average mean removal efficiencies of 62 to 95% for Cu, Fe, Mn and Zn and of 30 to 71% for NTK and P-total. There was removal efficiency of total and fecal coliforms of 91,935 to 99,667% however, a number of fecal coliforms above 1,5 x 105 NMP/100 mL was observed on the effluents, which restricts its use for crop irrigation ...(Complete abstract, click electronic access below)

Made available in DSpace on 2014-06-11T19:22:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-03-28Bitstream added on 2014-06-13T19:28:24Z : No. of bitstreams: 1 eleno_tg_me_rcla.pdf: 195961 bytes, checksum: 300673910af83cc4b49149d1b3f5f5a0 (MD5) / Conhecimentos sobre a participação dos metabolismos aeróbio e anaeróbio em exercício são importantes para compreender e prever os efeitos dos diferentes tipos de treinamentos. Muitos modelos têm sido propostos para a predição da participação dessas duas vias energéticas no exercício. Um deles, proposto em 1965, sugere a existência de uma intensidade de esforço, denominada potência crítica (PC), abaixo da qual o suprimento energético é dependente exclusivamente do metabolismo aeróbio. Até a intensidade da PC, o exercício pode ser realizado por longo tempo, sem exaustão. Acima dessa intensidade, as reservas anaeróbias de energia de dimensão finita denominada capacidade de trabalho anaeróbio (CTA), são requeridas e sua total depleção está associada com a exaustão. A aplicabilidade deste modelo vem sendo estudada e comprovada em exercícios contínuos, constituindo uma forma simples e não invasiva de se determinar as capacidades aeróbia e anaeróbia. O propósito deste estudo foi explorar o exercício intermitente através do modelo da potência crítica, principalmente quanto aos efeitos da duração da pausa na reposição da CTA. Indivíduos ativos foram submetidos a exercícios contínuos e intermitentes realizados em cicloergômetro, até a exaustão. Para os testes intermitentes, os regimes de esforço-pausa foram 15 s de exercício por 15 s, 30 s, 45 s e 60 s de pausa passiva. A PC e CTA foram determinadas a partir dos testes contínuos, através de regressão linear simples, segundo a equação P = CTA x 1/tlim + PC. A comparação entre as variáveis foi realizada através da análise de variância (ANOVA) para medidas repetidas, com nível de significância de 5% (p<0,05). Os principais resultados indicam que: da quantidade total de trabalho intermitente realizado, aproximadamente 58%, 85%, 88% e 90% correspondeu ao... / The knowledge of the contribution of aerobic and anaerobic metabolism during exercises plays a key role to anticipate the effects of different types of training. Many models have been proposed to predict the contribution of these two energetic pathways on the exercise work output. Among them, a model, proposed by Monod and Scherrer in 1965, suggests the existence of an exercise's intensity, named critical power (CP), below which the energetic supply is dependent, exclusively, on the aerobic metabolism. At the intensity corresponding to or below the critical power, the exercise can be done for a long time without exhaustion. Above this intensity, the finite anaerobic reserves of energy named anaerobic work capacity (AWC) are required and its total depletion is associated with exhaustion. The applicability of this model has been studied and confirmed in continuous exercises. It has been recognized as a simple and not invasive procedure to determine aerobic and anaerobic capacities. The purpose of this study was to explore the intermittent exercise through the critical power model, specifically the effects of the pause's duration on the replacement of the AWC. Active subjects were submitted to a continuous and intermittent ciclergometer exercises until exhaustion. For the intermittent tests, the exercise rest regimes were 15 s of exercise and 15 s, 30 s, 45 s and 60 s of passive recovery. The CP and AWC were determined by the results of continuous tests through a simple linear equation: P = AWC x 1/tlim + CP. The comparison among the variables was done by the analysis of variance (ANOVA) for repeated measures with a significance level of 5% (p<0,05). The main results indicated that: 1) from the total amount of intermittent work, approximately 58%, 85%, 88% and 90% was extra when compared to the continuous exercise for the same time of tests with 15 s, 30... (Complete abstract, click electronic address below)

O presente trabalho propõe-se a verificar a viabilidade de utilização do reator anaeróbio horizontal do leito fixo (RAHLF) para o tratamento da vinhaça sob condições termofílicas, com ênfase na etapa de partida do reator. O RAHLF tem sido utilizado com êxito no tratamento de diversos efluentes sob condições mesofílicas, em experimentos de bancada. Referências bibliográficas indicam que reatores do tipo UASB tratando vinhaça sob condições termofílicas, atingem remoção de DQD da ordem de 70% e composição do gás com até 60% de metano. Neste experimento, os dados obtidos de remoção de DQD foram de aproximadamente 70% para valores de DQD afluente da ordem de 10.000 miligramas por litro e porcentagem de metano no gás de 63%, dados esses que indicam a viabilidade do tratamento da vinhaça neste reator. Resulta-se a natureza de pesquisa exploratória desta etapa dos trabalhos, sendo necessária a realização de etapa complementar visando otimizar o tempo de detenção hidráulica e a carga orgânica máxima a ser utlizada. Como um estudo preliminar os resultados foram satisfatórios. / The present work proposes to verify the viability to use the Horizontal Anaerobic Immobilized Sludge (HAIS) reactor for the vinasse treatment in termophilic conditions, with emphasis in the reactor departure. The HAIS reactor has being to utilize with success on the treatment of many effluents under mesophilic conditions in workbench experiments. Bibliographic references indicate that reactors the UASB kind treat vinasse under termophilic conditions, arrive removal the COD (chernical oxygen demand) in the order the 70% and gas composition with 60% of methane. In this experiment, the data obtained the removal of COD were about 70% for values de affluent COD the order the 10.000 mg/L and percentage the methane in the gas the 63%, data these that indicate the viability the termophilic treatment of vinasse in this reactor. Stick out it the nature the exploratory research in this stage the work being necessary the realization the complementary stage aiming at optirnize the hydraulic detention time and the maxim organic load to be utilized. How a preliminary study the results were satisfactory.

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

An investigation of the biodegradation of complex hydrocarbon wastes, with emphasis on chlorinated aromatic compounds, in an anaerobic/aerobic bioprocess environment was made. A reactor configuration was developed consisting of linked anaerobic and aerobic reactors which served as the model for a proposed bioremediation strategy targeting subterranean soil/sediment/aquifer chlorinated phenol-contaminated environments. Here oxygen is frequently limited and sulphate is readily available, as occurs especially in marine sediment and intertidal habitats. In the anaerobic system the successful transformation and mobilization of the model contaminant, 2,4,6-trichlorophenol, was shown to rely on reductive dechlorination by a sulphate-reducing dependent dechlororespiring co-culture. This was followed in the aerobic system by degradation of the pollutant and its metabolites, 2,4-dichlorophenol, 4-chlorophenol and phenol, by immobilized white-rot fungi.The strategy was initially investigated separately in laboratory bench- and intermediate scale reactors whereafter reactors were linked to simulate the integrated biodegradation strategy. The application of the fungal reactor to treat an actual waste stream by degrading complex mixtures of hydrocarbons in a waste oil recycling effluent was also investigated. The mineralization of phenol and 2,4,6-TCP by immobilized fungal cultures was studied in pinewood chip and foam glass bead-packed trickling reactors. The reactors were operated in sequencing batch format. Removal efficiency increased over time and elevated influent phenol and TCP (800 and 85 mg.L⁻¹) concentrations were degraded by > 98 % in 24 – 30 h batch cycles. Comparable performance between the packing materials was shown. Uptake by the packing was negligible and stripping of compounds induced by aeration had a minimal effect on biodegradation efficiency. Reactor performances are discussed in relation to sequencing batch operation and nutrient requirements necessary to sustain fungal activity in inert vs. organic material packed systems. It was shown that a co-culture consisting of sulphate-reducing and dechlororespiring bacteria established in fed-batch and soil flasks, as well as pine chip-packed fluidized bed reactors. Results showed reductive dechlorination of 2,4,6-TCP to be in strict dependence on the activity of the sulphate-reducing population, sulphate and lactate concentrations. Transformation to 2,4-DCP, 4-CP and phenol was enhanced in sulphate deficient conditions. Dechlororespiring activity was found to be dependent on the fermentative activity of sulphate-reducing bacteria, and the culture was also shown to mobilize and dechlorinate TCP in soils contaminated with the pollutant. Linking the systems achieved degradation of the compound by > 99 % through fungal mineralization of metabolites produced in the dechlororespiring stage of the system. pH correction to the anaerobic reactor was found to be necessary since acidic effluent from the fungal reactor inhibited sulphate reduction and dechlorination. The fungal reactor system was evaluated at intermediate-scale using a complex waste oil recycling effluent. Substantial COD reduction (> 96 % in 48 h batch cycles) and removal of specific effluent hydrocarbon components was shown in diluted, undiluted (COD > 37 g.L⁻¹) and 2,4,6-TCP-spiked effluents. Industrial application of the fungal reactor was evaluated in a 14 m³ pilot plant operated on-site at a waste oil processing plant.

Orientador: Roberto Alves de Oliveira / Banca: Edson Aparecido Abdul Nour / Banca: Maria Bernadete Amâncio Varesche / Resumo: Neste trabalho avaliou-se o desempenho de processo anaeróbio em dois estágios composto por reator compartimentado (ABR) e reator de fluxo ascendente com manta de lodo (UASB), instalados em série, em escala-piloto (volumes de 530 e 120 L, respectivamente), tratando águas residuárias de suinocultura com concentrações de sólidos suspensos totais de 4.591 a 13.001 mg L-1, submetidos a tempos de detenção hidráulica (TDH) de 60 a 24 h no primeiro reator e de 13,6 a 5,4 h no segundo reator. As eficiências médias de remoção de DQOtotal variaram de 69 a 88% no reator ABR e de 34 a 58% no reator UASB, resultando em valores médios de 87 a 95% para o sistema de tratamento anaeróbio em dois estágios (ABR+UASB) com carga orgânica volumétrica (COV) de 11,51 a 21,12 g DQOtotal (L d)-1 no reator ABR, e de 4,21 a 13,29 g DQOtotal (L d)-1 no reator UASB. As eficiências de remoção de SST e SSV variaram de 86 a 96% e 88 a 97% no sistema de tratamento (ABR+UASB). A produção volumétrica de metano máxima de 0,455 m3 CH4 (m3 reator d)-1 ocorreu no reator ABR, com COV de 13,42 g DQOtotal (L d)-1 e TDH de 48 h. Obtiveram-se eficiências médias de remoção de 62 a 95% para Cu, Fe, Mn e Zn e de 30 a 71% para NTK e P-total. Houve remoção de coliformes totais e fecais de 91,935 a 99,667% porém, foram observados nos efluentes número de coliformes fecais acima de 1,5 x 105 NMP/100 mL, o que restringe sua aplicação para a irrigação de plantas ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work it was evaluated the performance of two stage anaerobic process constituted of anaerobic baffled reactor (ABR) and an upflow sludge blanket reactor (UASB) installed in series, in pilot scale testing (volumes of 530 and 120 L, respectively) treating swine wastewater with total suspended solid (TSS) concentration of 4591 a 13001 mg L-1 on and with hydraulic detention times (HDT) of 60 to 24 h in the first reactor and 13,6 to 5,4 h in the second reactor. The mean CODtotal removal efficiency varied from 69 to 88% in ABR and from 34 to 58% in UASB reactor, resulting in average values ranging from 87 to 95% for the two stage anaerobic treatment system (ABR+UASB) under organic volumetric load (OVL) of 11.51 to 21.12 g CODtotal (L d)-1 in ABR and 4.21 to 13.29 g CODtotal (L d)-1 in UASB reactor. The TSS and VSS removal efficiency varied from 86 to 96% and 88 to 97% in anaerobic treatment system (ABR+UASB). The maximum volumetric methane production of 0.455 m3 CH4 (m3 reactor d)-1 occurred in ABR reactor with OVL of 13.42 g CODtotal (L d)-1 and HDT of 48 h. The average mean removal efficiencies of 62 to 95% for Cu, Fe, Mn and Zn and of 30 to 71% for NTK and P-total. There was removal efficiency of total and fecal coliforms of 91,935 to 99,667% however, a number of fecal coliforms above 1,5 x 105 NMP/100 mL was observed on the effluents, which restricts its use for crop irrigation ...(Complete abstract, click electronic access below) / Mestre

This study was conducted to address the controlling factors of biosolids stability as they relate to mesophilic anaerobic digestion, dewatering processes and digestion enhancement by wet sludge disintegration technologies. The working hypothesis of this study is that digestion performance; nuisance odor generation and the degree of digestion enhancement by wet sludge disintegration are directly related to anaerobic floc structure and its interaction with shearing forces. Mesophilic digestion was studied in two modes of operation, convention high rate and internal recycle mode to enhanced digestion using a wet sludge disintegration device. The internal recycle system operated on the premise that stabilized sludge would be removed from the digester disintegrated, either by mechanical shear or ultrasonic disintegration for this study, and returned it for to the digester further for further stabilization. Both benchscale and full-scale demonstrations found this mode of digestion enhancement to be effective for mechanical shear and ultrasonic disintegration. It was also determined that volatile solids destruction in both conventional and enhanced mesophilic anaerobic digesters can be reasonably predicted by the concentration of cations in the sludge being treated. It was found that depending on the disintegration device used to enhance digestion performance was influenced by different cation associated fractions of the sludge floc. Along with the improvement of digester performance, overall biosolids stability was investigated through of volatile organic sulfur emissions from dewatered biosolids. In doing so, a method to mimic high solids centrifugation in the laboratory was developed. The centrifugation method identified three major factors that contribute to the generation of odors from biosolids: shear, polymer dose, and cake dryness. The inclusion of shearings suggest that one means of reducing odors from biosolids generated by centrifugation is to use a shear enhanced digestion technology to degrade odor precursors, such as amino acids, within the digester prior to dewatering. Furthermore, the mechanical shearing within a digester is thought to be similar to that of mechanical shear enhanced digestion; therefore, the floc properties that control the digestion process would control observed odor generation. / Ph. D.

Wastewater treatment performance of three pilot-scale packed-bed anaerobic digesters with walnut shell medium was researched for treating dairy freestall barn flushwater. Reciprocation mixing was evaluated as a means to lessen channelization in the media bed and to improve biogas production and organic matter removal at ambient temperatures. Reciprocation has been used in biological nitrogen removal systems to introduce air into the system to repeatedly oxygenate nitrifying biofilm along with mixing (Behrends et al. 2003), but the anaerobic systems benefit from mixing. Two tanks were used in each system, where one was full and one was empty at any given time. Water was repeatedly pumped from one tank to the other and back again (reciprocation). A key research objective was to determine the minimum reciprocation frequency (between 0-10 per day) while still maintaining moderate methane production and treatment performance. Broken walnut shells with a specific surface area of 360 m2/m3 were used as the packed media. Digester influent, which was pretreated to remove large solids, had the following characteristics: total solids (TS) of 5.5 g/L, volatile solids (VS) of 2.8 g/L, 5-day carbonaceous biochemical oxygen demand (cBOD5) of 800 mg/L, and chemical oxygen demand (COD) of 4340 mg/L. Average digesting liquid temperatures ranged from 14.1 to 23.6 °C. At 6-day theoretical hydraulic residence times (V/Q where V is Lliquid, which is volume of liquid occupying the digester pores, and Q is total daily influent flow) and 1 reciprocation per day, methane production was 0.060 ± 0.10 LCH4/Lliquid-day and at 10 reciprocations methane production 0.058 ± 0.14 LCH4/Lliquid-day (mean ± standard deviation of measurements over time). COD percent removals were both 51% at 6-day V/Q. Since multiple reciprocations did not appear to make a difference in methane production and treatment performance, fewer reciprocations were used in subsequent experiments. Higher flow rates were also used in subsequent experiments to accelerate sludge clogging and channelization in the walnut-shell bed and thereby allow detection of any advantage provided by reciprocation compared to an upflow reactor. At 0 and 1 reciprocations per day and 0.35 and 0.50-day V/Qs, respectively, methane production was 0.24 ± 0.08 and 0.23 ± 0.08 LCH4/Lliquid-day and COD percent removal was 17 and 22%. Over the study period of 226 days, walnut shell porosities decreased due to sludge accumulation from 0.68 and 0.64 (start-up or clean-bed) to 0.31 and 0.24 in the 1 and 0 reciprocation per day reactors. Sludge accumulation and channelization did not appear to be affected by reciprocation mixing on the scale of this study.

Anaerobic Digestion (AD) is an essential component in wastewater treatment to recover energy from waste and deals with sludge management issues effectively. AD is a treatment process that converts organic matter to methane and carbon dioxide with multi-step biological reactions. Methanogenesis, the subprocess of AD that produces methane, is an important indicator of the stability of AD and is influenced by pH, temperature, ammonia, volatile fatty acids (VFAs), and solids concentrations among other factors. Ammonia is an essential nutrient for methanogenic bacteria but at certain ammonia concentrations and pH levels, ammonia is said to be a toxicant for methanogenic archaea. Substrates that are high in ammonia content can include those high in protein, such as food waste, which can be inhibitory to methanogens in the digestion process. Thickened waste activated sludge (TWAS) also contains a large amount of nitrogen with its higher solids concentration, promoting methane production. VFAs are produced during acidogenesis and they can negatively affect methanogenic archaea. High organic loading rates into AD can lead to an accumulation of VFAs and thus inhibition of methanogenic activity. Even with well-known inhibitory effects of ammonia and VFAs on methanogenesis, there are limited tools available for modelling these inhibitions, especially when evaluating diverse compositions of substrate. The objectives of this research work are to experiment for various pairings of pH, ammonia, and acetate levels using batch reactors and to quantify the inhibition on the overall methane production using an AD-based model focused on biological reactions. / Thesis / Master of Applied Science (MASc)