I Sverige förekommer strikta krav på fosforrening av avloppsvatten och detta har bidragit till att kemisk fällning har kommit att dominera som reningsmetod för fosfor vid svenska avloppsreningsverk. Fällningskemikalier är dyrt för reningsverken att köpa in och ger negativ påverkan på miljön vid tillverkning och transport. Strängare reningskrav har ökat behovet av nya reningsmetoder som på ett effektivt och miljövänligt sätt kan rena avloppsvatten från näringsämnen utan att kostnaderna för reningen blir för stora. Biologisk fosforavskiljning (bio-P) utnyttjar mikroorganismer som naturligt kan ackumulera fosfor i sina celler. En kritisk faktor för en väl fungerande biologisk fosforavskiljning är tillgången till kolkälla i form av flyktiga fettsyror (VFA). Kommunalt avloppsvatten innehåller vanligen för lite VFA för att tillgodose bio-P-processens behov. Den totala tillgången på organiskt material i avloppsvattnet är dock ofta stor och möjligheten finns därmed att genom biologisk slamhydrolys internt producera VFA. Vid biologisk hydrolys av slam utnyttjas mikroorganismers naturliga förmåga att under anaeroba förhållanden bryta ned organiskt material till mer lättomsättliga föreningar. Duvbackens avloppsreningsverk i Gävle tillämpar biologisk fosforavskiljning och producerar VFA till bio-P-processen genom primärslamshydrolys och sidoströmshydrolys av returslam. I detta examensarbete har hydrolysprocesserna vid reningsverket utvärderats med avseende på processernas förmåga att producera VFA till det biologiska reningssteget. Utvärderingen gjordes genom att mäta förändringen i halten organiskt material över hydrolysbassängerna samt genom att bedöma effektiviteten i bio-P-processen i fullskala och vid labskaleförsök. Möjligheten att stänga av primärslamshydrolysen vid verket undersöktes. Ett försök till att optimera driften av sidoströmshydrolysen gjordes genom att utföra hydrolysförsök i laboratorieskala. Resultaten indikerade att produktionen av VFA i primärslamshydrolysen var begränsad och att processen därmed bör kunna stängas av. Innan detta görs bör dock kompletterande mätningar av halten löst COD över primärslamshydrolysen utföras. Vid samtliga mättillfällen uppmättes en betydande ökning i halten organiskt material över sidoströmshydrolysen. Baserat på detta och den i examensarbetet konstaterade effektiviteten i bio-P-processen drogs slutsatsen att sidoströmshydrolysprocessen vid Duvbackens reningsverk var välfungerande. Hydrolysförsöken pekade på att ett större utbyte av VFA skulle erhållas om en kortare uppehållstid än den nuvarande användes i sidoströmshydrolysen. Detta bör vidare undersökas genom fullskaleförsök vid verket. / The strong regulations concerning phosphorus removal from wastewater in Sweden has resulted in chemical precipitation being the most common treatment method for phosphorus at Swedish wastewater treatment plants (WWTP). Precipitation chemicals are expensive and have a negative environmental impact when produced and transported. More stringent wastewater treatment requirements have increased the need of new, eco-friendly treatment methods that effectively can remove nutrients from wastewater without being too expensive. Enhanced biological phosphorus removal (EBPR) utilizes microorganisms that have the natural capability of accumulating phosphorus in their cells. A critical factor for a well-functioning EBPR-process is the availability of carbon source in form of volatile fatty acids (VFA). Municipal wastewater normally contains too small amounts of VFA to satisfy the need of the EBPR-process. The total amount of organic matter in the wastewater is on the other hand large and the possibility consequently exists to internally produce VFA through sludge hydrolysis. Biological sludge hydrolysis takes advantage of the natural capability of microorganisms to degrade complex organic compounds into easily degradable organics. Duvbacken WWTP in Gävle uses EBRP for phosphorus removal and produces carbon source through hydrolysis of primary sludge and sidestream hydrolysis of return sludge. In this master thesis the hydrolysis processes at the WWTP was evaluated with regard to the capacity of the processes to produce VFA to the biological treatment step. The evaluation was performed by measuring the change in organic material content over the hydrolysis basins and by estimating the effectiveness of the EBPR-process in full scale and by laboratory experiments. The possibility to turn off the primary sludge hydrolysis process was examined. An attempt to optimize the operation of the sidestream hydrolysis process was made by conducting hydrolysis experiments in laboratory scale. The results indicated that the production of VFA by primary sludge hydrolysis was limited and that it thus would be possible to turn off the process. Before this is done complementary measurements of COD levels over the primary hydrolysis basin should be performed. At all times considerable increments in COD content was measured over the sidestream hydrolysis basin. Based on this and the in the thesis confirmed effectiveness of the EBRP-process the conclusion was drawn that the sidestream hydrolysis of return sludge at Duvbacken WWTP was well functioning. The hydrolysis experiments indicated that a larger VFA yield would be obtained if a shorter retention time than the present was used in the sidestream hydrolysis process. This should further be investigated by experiments in full scale at the WWTP.

This study was carried out to evaluate the potential of high-rate anaerobic digestion of high-solids organic fraction of municipal solid waste (OFMSW) for the production of organic acids and alcohols in leaching bed reactors (LBRs). For this purpose, two different experimental set-ups, namely Set-1 and Set-2, were operated. In the Set-1, only OFMSW without paper was studied in two identical LBRs, whereas, four identical LBRs, fed with OFMSW with paper and cow manure in different proportions, were operated in the Set-2. In this study, 50-60% of hydrolysis efficiency was achieved in the LBRs of Set-1, whereas this value was decreased to 20-25% in the LBRs of Set-2 / which was resulted from OFMSW containing cellulose and less volume of water addition in the Set-2. The mass of total volatile fatty acids (tVFA) production was found as 7000-9000 mg at the end of 80 days in the LBRs of Set-1, fed with OFMSW without paper, whereas it was 3000 mg at the end of 40 days in the LBR of Set-2, containing only OFMSW with paper. It was also observed that cow manure addition increased the amount of tVFA production in the LBR of Set-2. In conclusion, LBRs were found as alternative reactors for the degradation of OFMSW compared to completely stirred tank reactors (CSTRs) in terms of rapid hydrolysis and acidification, which can result in high hydrolysis yield and tVFA production.

A análise de alimentos para ruminantes consite na caracterização da sua composição química, que varia em função da edafoclimatologia e manejo agrotécnico ao longo do tempo. O manejo de desfolhação (28 e 42 dias), o genótipo e estações constituem fonte de variação da degradabilidade in vitro da matéria seca (DIVMS), acúmulo de gases no rúmen (PG), metano (CH4) e do perfil dos ácidos graxos de cadeia curta (AGCC), com reflexos na eficiência da produção animal. A introdução dessas práticas no cultivo dos gêneros Brachiarias e Cynodon pode disponibilizar forragem de boa qualidade nutricional, com baixos teores de fibra. As dietas baseadas nas gramíneas tropicais são ricas e fibra e trazem controvérsias nos sistemas de produção de ruminantes, pela emissão de dióxido de carbono (CO2) e de CH4 entéricos, com efeito de estufa (GEE) na atmosfera, proposto para reduzir pela comunidade internacional. Contudo, a mitigação dos GEE exige a quantificação da sua produção por área, animal e por ano. Econmicamente, o CH4 enterico é uma perda de 2-12% de energia que poderia ser convertida em produto animal. O objetivo do estudo foi descrever e explicar os efeitos da frequência de desfolhação (28 e 42 dias), genótipo e estações do ano na composição química, DIVMS, PG, CH4, no perfil dos AGCC e no fator de partição (FP) da Brachiaria brizantha cv. Marandu, Brachiaria híbrida cv. Mulato II (Convert HD 364®) e do Tifton 85 (Cynodon spp.), cultivados em 2012/2013. A matéria seca (MS%) da forragem cortada a cada 42 dias aumentou nos dois anos de experimento e diminuiu para o Marandu e o Mulato II. A matéria mineral (MM) na forragem aumentou em corte de 42 dias e no 2º ano. A matéria orgânica (MO) foi maior para o Marandu e Mulato II nas duas frequências de corte, comparada com a do Tifton 85. As médias mais baixas de fibra em detergente neutro (FDN), ácido (FDA) e extrato etéreo (EE) foram observadas no corte de 28 dias segundo a ordem: FDN, MM, FDA Tifton 85 >Marandu > Mulato e para DIVMS foi Marandu > Mulato II > Tifton 85 no outono-inverno. A PG foi superior para todos os genótipos na primavera-verão em relação ao outono-inverno. Contrariamente, o CH4 teve aumentos de 11,7% (Marandu), 29,2% (Mulato) e 41,4% (Tifton 85), no outono-inverno. O volume de CH4 das espécies foi diferente nas colheitas de 28 d de rebrotação. O FP variou pouco entre frequências, mas sim com a as estações do ano. A relação estequiométrica do acetato, propionato, e butirato foi 6,2:3,0:1,0 (estação) a 7,5:3,2:1,0 (ano). As relações acetato: propionato e TAGCC: MSD tiveram padrão de variação constante ao longo dos tratamentos. Conclui-se que a DIVMS e o perfil de AGCC são menos afetados pelas estações do ano do que pelas frequências de corte e estas praticas tendem a melhorar a qualidade da forragem colhida na frequência de rebrotação mais longa. Os teores de PB, CC, MO, EE foram altos nas duas frequências de corte e no inverno. / Ruminant feed analysis characterizes nutritional quality as described by its chemical composition (CC). The CC of forage grasses, however, varies with edaphoclimate, agronomic management (soil fertility, irrigation and harvesting frequency), which can change dry matter degradability (DMD), rumen gas production (GP), CH4, and volatile fatty acids (VTA) profile in the rumen, impacting animal production efficiency. The introduction of such practices in Brachiaria and Cynodon spp. Production system may enhance the production of green, high quality and nutritional forage. Hydrolyzed forage results in VFA, the energy that generate milk and meat. However, tropical grasses diets, rich in fiber, contribute for green house gas (GHG) and bring controversies in the system associated to the atmosphere global warming.The international community calls for GHG reduction quantifying the amount produced in the system. Economically, the emission of CH4 by the animal represents 2-12% energy loss that could be converted into animal products. The objective of the study is to describe and explain the effects of clipping frequency (28 and 42 days interval), season and year on CC, GP, CH4, in vitro DMD and PF of Brachiaria brizantha cv. Marandu, Brachiaria Hybrid cv. Mulato II (Convert HD 364®) and Tifton 85 [Cynodon dactylon (L.)], under intensive management, form 2011 to 2013. Forage desfoliated at 42 days (d) intervals increased dry matter (DM) and ash (MM) content of Tifton 85 and Brachiaria sp., respectively. Organic matter (MO) of Marandu and Mulato II is high on both cutting frequencies compared to that of Tifton 85.The lowest NDF, ADF and EE were recorded at 28d forage regrowth. The ranking of NDF, MM, FDA for forage was Tifton 85> Marandu> Mulato) and IVDMD (Marandu> Mulato II> Tifton 85) in autumn-winter. Gas production was high for all species in summer-spring than autumn-winter, while CH4 increased 11.7% (Marandu), 29.2% (Mulato II) and 41.4% (Tifton 85), in autumn-winter. Harvesting at 28 d interval changed CH4 yield for the species. The FP varied sitghtly between frequencies, but with the seasons. The averages of acetic, propionic, butyric acids followed stachiometric relationship of 6.2: 3.0: 1.0 to 7.5: 3.2: 1.0 for season and year. The acetate to propionate and AGCC to MSD ratio had constant pattern but changed over treatments. We conclude that fertilized and irrigated grasses\'s IVDMD and VFA are less affected by the seasons than the harvesting frequencies and these practices improve the quality of harvested forage in both regrowth frequencies. Forage PB, CC, MO and EE are higher in both summer and winter as well as in the long cutting interval.

Made available in DSpace on 2017-07-10T18:08:18Z (GMT). No. of bitstreams: 1 Citieli Giongo.pdf: 582976 bytes, checksum: f111bc4e475aed239fba2b45a360406b (MD5) Previous issue date: 2011-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The cultivation of cassava extends throughout Brazil because of its excellent adaptation to different soils and climatic conditions. Our country occupies the second position at the worldwide ranking in cultivating this plant (15% of the world production). The industrial processing of cassava generates a liquid waste, the so called manipueira, considered as a pollutant due to the high organic load and it contains a cyanogenic glycoside, which can be hydrolyzed to cyanide. One way to minimize environmental impacts and to aggregate value to the effluent is its use in the production of volatile fatty acids (VFA) via anaerobic fermentation, which was the main goal of this study, performed using manipueira as a substrate and inoculum of swine dejection. The fermentation process during the production of VFA is characterized as a result of the activity of acidogenic bacteria, by the pH decrease and increased hydrolysis and acidification of the organic matter. Inoculum of swine and of bovine dejections were tested in synthetic medium at 30°C and initial pH of 7.0, to define the most appropriate inoculum for the production of volatile fatty acids, swine dejection presented the best results and was used in posterior fermentations. Besides the parameter of VFA production, the behavior of pH, alkalinity and acidity were as well monitored in all experiments. In the fermentation performed with manipueira as a substrate, glucose was used as the main carbon source and different concentrations were tested (1, 2, 5 and 9 g/L) and it was observed that the concentration of 2 g/L of glucose produced about 2.5 g/L of VFA, expressed as acetic acid, after 36h and at pH 5.0, this concentration of glucose was used in further experiments. The alkalinity and temperature levels were tested by experimental design, in which at 30°C with 3 g/L of sodium bicarbonate better conditions were observed, resulting in the production of 3.4 g/L of VFA in 45h. On the basis of these conditions, the model for the production of VFAs was validated by performing fermentations in triplicate and evaluating the reproducibility of the process. There were minor variations between replicates, as assessed by the low relative standard deviation (RSD) from the mean value of the results. The highest production of volatile fatty acids in this experiment was obtained at 45h with an average of VFAs production of 3.4 g/L, with RSD of 1.4% and pH 5.6. The chemical oxygen demand (COD) and the amount of cyanide in manipueira were analyzed being 8865 mg/L of O2 and 1.9 mg/L, respectively, among other physical and chemical characteristics that were determined. After the anaerobic fermentation process, a reduction of 21.6% of COD amount and 12.9% of cyanide amount were obtained, indicating that the production of VFAs not only aggregates value to the manipueira but also contributes to the reduction of important contaminants. / O cultivo da mandioca se estende por todo o Brasil, dada à fácil adaptação aos diferentes tipos de solos e condições climáticas. Nosso país ocupa o segundo lugar no cultivo dessa planta (15% da produção mundial). O processamento industrial da mandioca gera a manipueira como resíduo líquido, considerado poluente devido à alta carga orgânica e por conter um glicosídeo cianogênico que é hidrolisável a cianeto. Uma das maneiras de minimizar os impactos ambientais e agregar valor ao efluente é a sua utilização na produção de ácidos graxos voláteis (AGVs) via fermentação anaeróbia, objetivo principal deste trabalho, o qual foi realizado utilizando a manipueira como substrato e inóculo de dejeto suíno. O processo fermentativo na produção dos AGVs caracteriza-se, como resultado da atividade das bactérias acidogênicas, pela diminuição do pH e aumento da hidrólise e acidificação da matéria orgânica. Foram testados em meio sintético, à temperatura de 30 ºC e pH inicial de 7,0, inóculos de dejetos de suínos e bovinos para definir o melhor inóculo na produção dos ácidos graxos voláteis, sendo o dejeto de suíno o que apresentou os melhores resultados e por isso foi utilizado nas fermentações posteriores. Além do parâmetro de produção de AGVs também foram monitorados o comportamento do pH, acidez e alcalinidade em todos os experimentos. Em fermentações realizadas com a manipueira como substrato, testaram-se diferentes concentrações de glicose como principal fonte de carbono (1, 2, 5 e 9 g/L) e observou-se que a concentração de 2 g/L de glicose produziu cerca de 2,5 g/L de AGVs, expressos como ácido acético, em 36h e com pH 5,0, sendo esta a concentração de glicose utilizada nos experimentos posteriores. Diferentes níveis de alcalinidade e temperatura foram testados através de planejamentos experimentais em que a melhor condição observada foi em 30ºC com 3 g/L de bicarbonato de sódio, obtendo-se 3,4 g/L de AGVs em 45h. A partir dessas condições validou-se o modelo para produção de AGVs realizando fermentações em triplicata e avaliando quanto à repetibilidade do processo. Verificaram-se variações mínimas entre as réplicas, avaliadas pelo baixo desvio padrão relativo (DPR) obtido pela média dos resultados. A maior produção de ácidos graxos voláteis neste experimento foi obtida em 45h com média de 3,4 g/L de AGVs, DPR de 1,4% e pH em 5,6. A demanda química de oxigênio (DQO) e a quantidade de cianeto analisadas na manipueira eram de 8865 mg/L de O2 e 1,9 mg/L, respectivamente, entre outras características físico-químicas determinadas. Após o processo de fermentação anaeróbia obteve-se redução de 21,6% da quantidade de DQO e 12,9% da quantidade de cianeto, indicando que a produção de AGVs, além de agregar valor a manipueira, contribui na redução de contaminantes importantes.

A matéria orgânica presente nas águas residuárias representa uma matéria prima barata para integrar o processo de digestão anaeróbia e gerar fontes de energia alternativas, como o hidrogênio. O hidrogênio pode substituir os combustíveis fósseis não renováveis e diminuir as emissões de gases do efeito estufa responsável por grande parte da mudança climática global. A combustão do hidrogênio com o oxigênio produz somente vapor d\'água e representa 2,75 vezes mais conteúdo de energia que qualquer hidrocarboneto. Além disso, os ácidos orgânicos gerados no processo podem ser utilizados como fonte de carbono para a produção de metano, hidrogênio por organismos fototróficos e biopolímeros e, para a remoção de nutrientes biológicos. A produção de hidrogênio tem sido estudada em reatores de crescimento suspenso e de crescimento imobilizado como o reator anaeróbio de manta de lodo (UASB), reator anaeróbio de leito fixo e reator anaeróbio de leito fluidificado. O objetivo desse estudo foi avaliar a produção de hidrogênio e ácidos orgânicos em um reator anaeróbio de leito fluidificado contendo argila expandida como material suporte. O reator tinha 190 cm de altura, 5 cm de diâmetro interno e um volume de 4192 \'CM POT.3\'. O reator foi inoculado com lodo pré-tratado termicamente a 90°C por 10 minutos para o enriquecimento do inóculo acidogênico. O sistema foi operado com tempo de detenção hidráulica (TDH) de 8, 6, 4, 2 e 1 h e foi alimentado com água residuária sintética contendo 2000 mg/L de glicose. A operação contínua teve duração de 178 dias, e em cada TDH o reator foi operado durante, aproximadamente, 30 dias. A 30°C e pH de 3,8, cerca de 92 a 98% da glicose foi removida. A diminuição do TDH de 8 para 1 h conduziu a um aumento na velocidade média de produção de hidrogênio volumétrico de 0,28 para 1,15 L/h.L, respectivamente. A máxima velocidade de produção de hidrogênio, de 1,15 L/h.L, foi obtida em TDH de 1 h. Em geral, o rendimento de produção de hidrogênio aumentou com a diminuição do TDH, de 1,84 mols \'H IND.2\'/mol glicose em TDH de 8 h para 2,29 mols \'H IND.2\'/mol glicose em TDH de 2 h. O biogás não continha metano e o conteúdo máximo de hidrogênio foi de 37% em TDH de 2 h. Foi observada uma correlação linear entre a velocidade de produção de hidrogênio e a taxa de carregamento orgânico (TCO). Ainda, a TCO máxima de 104 kg/\'M POT.3\'.d não inibiu a produção de hidrogênio. Os maiores metabólitos solúveis foram o ácido butírico (44,64-52,52%) e o ácido acético (41,17-47,48%) com insignificante concentração de etanol (menor do que 10%). A produção de hidrogênio estável e a porcentagem de ácido butírico sobre o ácido acético indicam que o tratamento térmico do lodo foi efetivo e uma típica fermentação do tipo ácido butírico pode ser assegurada por Clostridium. Além disso, foram alcançados bons desempenhos de produção de hidrogênio sob condições de pH em torno de 4,0. / Organic materials in the wastewater can be an inexpensive raw material for integrating fermentation process and suppling renewable energy source such as hydrogen. Nevertheless hydrogen can replace fossil fuels and reduce greenhouse gases responsible for global climate change. The hydrogen combustion with oxygen produces only water vapor and hydrogen gas has 2.75 times the energy content of any hydrocarbons. Furthermore, the volatile fatty acids production can be used as carbon source for methane, photosynthetic hydrogen, bioplastics production and biological nutrients removal. The hydrogen production was carried out in suspend cell system, anaerobic sludge blanket reactor, fixed bed reactors and fluidized bed reactors. The objective of this study was to evaluate the hydrogen and volatile fatty acids production in an anaerobic fluidized bed reactor containing expanded clay like a material to immobilize acclimated anaerobic sludge. The reactor has presented 190 cm high, 5 cm in internal diameter and volume of 4192 \'CM POT.3\'. The reactor was seeded with a heat treated sludge at 90°C for 10 minutes for enriching \'H IND.2\' producing inoculum and supressing methanogens. The system was operated at hydraulic retention time (HRT) of 8, 6, 4, 2 and 1 h and was fed with syntetic wastewater containing 2.000 mg glucose/L. The continuous operation lasted 178 days, and in each TDH the reactor was operated for approximately 30 days. At 30°C and pH 3.8, about 92-98% of glucose was removed. The decrease of HRT from 8.0 to 1.0 led to a marked increase in the mean volumetric hydrogen production rate from 0.28 to 1.15 L/h.L, respectively. The maximum volumetric hydrogen production rate, 1.15 L/h.L, was obtained at HRT of 1.0 h. In general, the hydrogen yield increase from 1.84 mol \'H IND.2\'/mol glucose at HRT of 8.0 h to 2.29 mol \'H IND.2\'/mol glucose at HRT of 2.0 h. The biogas was free methane and the hydrogen content accounted for 37% at HRT of 2.0 h. There was a linear correlation between the hydrogen production rate and the organic loading rate (OLR) and the maximum OLR, 104 Kg/\'M POT.3\'.d, is not expected to inhibit hydrogen production. The major soluble products were butyric acid (44.64- 52.52%) and acetic acid (41.17-47.48%) further ethanol was relatively insignificant (less than 10%). The stable hydrogen production and the percentagen of butyric acid over acetic acid indicated the heat treated sludge was effective and a typical butyrate type fermentation was achieved by Clostridium. In addition, hydrogen production could be performed under pH conditions near 4.0.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Lipid additives used in the nutrition of dairy cows may affect both milk fat composition, as modifying the individual fatty acid profile, reducing methane emissions, becoming a sustainable practice for dairy cattle. To verify the effect of an additive based on medium chain fatty acids (MCFA) containing caproic acid, caprylic, capric, lauric and myristic, four treatments were tested: CTL (control without addition of MCFA), AGCM20 (5g MCFA), AGCM40 (10g MCFA) and AGCM80 (20g MCFA) on in vitro production gas (Experiment 1) and in the diet of lactating cows (Experiment 2). The bottles were distributed in a completely randomized design with repeated measurements over time and animals in triple latin square with four animals, four periods, four treatment, respectively. In Experiment 1 evaluated the production of gas, short chain fatty acids (SCFA) and methane (CH4); in Experiment 2 the productive parameters of milk and individual profile of fatty acids of milk fat. There was a significant decrease in gas production and methane (P<0.05), changing the profile of SCFA production in vitro treatment gas in AGCM40 and 80 compared with the control. No effects on productive parameters (P>0.05), however, were observed linear increase of C17:0 and C18: 3n6 (P<0.05) in the treatments AGCM20 and 80 respectively. It has been found that the use of MCFA 10 and 20g reduce the production of methane, without altering milk production and fatty acids of milk. / Aditivos lipídicos utilizados na nutrição de vacas leiteiras podem afetar tanto a composição da gordura do leite, quanto modificar o perfil de ácidos graxos individuais, reduzindo as emissões de metano, tornando-se uma prática sustentável para pecuária leiteira. Para verificar o efeito de um aditivo a base de ácidos graxos de cadeia média (AGCM), contendo ácido capróico, caprílico, cáprico, láurico e mirístico, foram testados quatro tratamentos: CTL (controle, sem suplementação), AGCM20 (5g AGCM), AGCM40 (10g AGCM) e AGCM80 (20g AGCM) na produção in vitro gás (Experimento 1) e na dieta de vacas em lactação (Experimento 2). Os frascos foram distribuídos em um delineamento inteiramente casualizado com medidas repetidas no tempo e os animais em um triplo quadrado latino, com quatro animais, quatro períodos, quatro tratamentos, respectivamente. No experimento 1 foram avaliados a produção de gás, ácidos graxos de cadeia curta (AGCC) e metano (CH4); no Experimento 2 os parâmetros produtivos de leite e perfil individual dos ácidos graxos da gordura do leite. Houve redução significativa na produção de gás e metano (P<0,05), alterando o perfil de AGCC na produção in vitro gás nos tratamento AGCM40 e 80 em comparação com o controle. Não foram observados efeitos nos parâmetros produtivos (P>0,05), entretanto, foram observados aumentos lineares de C17:0 e C18:3n6 (P<0,05), nos tratamentos AGCM20 e 80 respectivamente. Foi constatado que o uso de 10 e 20g de AGCM reduz a produção de metano, não alterando a produção de leite.

The gap between resource demand for the industrialized world and non-renewable feedstock like fossil fuels, essential agricultural fertilizer is getting increasingly severe, which has resulted in alarming-increasingly impacts on worldwide environmental problems. Meanwhile, wastewater treatment plants (WWTPs), as an essential facility for urbanization, is also confronting new rising challenges such as energy consumption and operation costs rather than only improving effluent wastewater quality. It is thereby important to develop new approaches for next-generation WWTPs with less energy consumption and costs in a sustainable way. The objective was to study the application of volatile fatty acids (VFAs) from waste as an external carbon source on denitrification by manometric tracking method in the lab-scale. Food waste and primary sludge were used for anaerobic fermentation to produce VFAs, which was then used as a sole external carbon source with various C/N ratio in denitrification batch test. The results were compared with traditional external carbon sources, acetate and methanol. It was found that the maximum denitrification rate with VFAs as an external carbon source was 15.73 ± 0.95 mg NOx-N/g VSS h, faster than those with acetate and methanol as external carbon sources. When C/N ratio ≥ 4.5 nitrate removal efficiency and the highest maximum denitrification rate were reached, the optimum C/N ratio for dosing VFAs as an external carbon source was thus determined as 4.5. In addition, denitrification capacity experiments with addition of VFAs produced from three different pH-controlled digestion reactors as an external carbon source were then conducted under an optimum C/N ratio of 4.5. As a result of the composition difference between VFAs produced from different pH environment, it was observed that, with VFAs from pH-10 digestion reactor denitrification rate was slightly higher than those with VFAs from pH-5 and none-pH-controlled digestion reactors. Furthermore, denitrification batch test using chemical tracking method was conducted to compare with manometric tracking method, and it was proven that the results obtained from manometric denitrification tests were reliable and valid. The overall results show that VFAs produced from anaerobic fermentation are an excellent external carbon source for denitrification, and it realizes the utilization of carbon resource recovery from WWTPs, which is crucial for next-generation wastewater treatment. / Klyftan mellan resursefterfrågan i den industrialiserade världen och icke-förnybar råvara som fossila bränslen, essentiell jordbruksgödsel, blir allt svårare, vilket har resulterat i oroväckande effekter på globala miljöproblem. Samtidigt står avloppsreningsverk (ARV), som är en viktig anläggning för urbanisering, inför nya ökande utmaningar som energiförbrukning och driftkostnader snarare än att förbättra kvaliteten på renat avloppsvatten. Det är därmed viktigt att utveckla nya strategier för nästa generations ARV med mindre energiförbrukning och kostnader på ett hållbart sätt. Målet var att studera tillämpningen av flyktiga fettsyror (VFA) från avfall som en extern kolkälla i denitrifikation med manometrisk metod i laboratorieskala. Matavfall och primärslam användes för anaerob rötning för att producera VFA, som sedan användes som en extern kolkälla med olika C/N-förhållanden i denitrifikationstest. Resultaten jämfördes med traditionella externa kolkällor, acetat och metanol. Det visade sig att maximal denitrifikationskapacitet med VFA som extern kolkälla var 15,73 ± 0,95 mg NOx-N/g VSS h, snabbare än de med acetat och metanol som extern kolkälla. När C/N-förhållandet ≥4,5 uppnåddes högsta nitratborttagningseffektivitet och maximala denitrifikationskapacitet, varför det optimala C/N-förhållandet för dosering av VFA som extern kolkälla bestäms som 4,5. Dessutom genomfördes experiment med denitrifikationskapacitets med tillsats av VFA producerat från tre olika pH-kontrollerade rötningsreaktorer som externa kolkällor under ett optimalt C/N-förhållande av 4,5. Som ett resultat av kompositionsskillnaden mellan VFA producerade från olika pH-miljöer, det observerades att med VFA från pH-10 kontrollerad reaktor denitrifikationskapacitet var något högre än med VFA från pH-5 och en icke-pH-kontrollerad reaktor. Vidare utfördes denitrifikationstest med användning av kemisk metod för jämförelse med manometrisk metod, och det visades att resultat erhållna från manometrisk denitrifikationstest var tillförlitliga och giltiga. De övergripande resultaten visar att VFA som produceras från anaerob rötning är en utmärkt extern kolkälla för denitrifikationsprocessen, vilket betyder att utnyttjandet av kolresursåtervinning från AVR är avgörande för nästa generations avloppsrening.

Polyhydroxyalkanoates (PHAs) are a group of bioplastics, which are produced through microorganisms. They are accumulated in granules inside bacteria’s cell cytoplasm and serve as an energy reserve. Moreover, PHAs are completely biodegradable and biocompatible biopolyesters, which make them to suitable materials for medical applications and replace conventional petrochemical plastics. However, it is not economically feasible to produce PHAs yet, as it is four to nine times as expensive as to produce fossil fuel-based plastics. In order to reduce the price, it is possible to use waste streams rich in carbon and mixed cultures as microorganisms, which was applied in this thesis work. In this study, PHAs were synthesized from a volatile fatty acid (VFA) mixture rich in hexanoic acid, which was produced by anaerobic digestion of waste streams. To be able to obtain the maximum PHA content, the experimental work was separated into a selection phase and a production phase respectively. During the selection step, enrichment of the mixed culture took place during 50 days altering feast/famine cycles. The production phase was then conducted in a fed-batch cultivation to accumulate as much PHAs as possible, while utilizing the enriched mixed culture.  The selection phase was seen as successful since the quantity of synthesized PHA increased with time. Solely polyhydroxybutyrate (PHB) was formed during this period. The specific consumption rates for the hexanoic acid and acetic acid were almost the same in this phase (0.10 g hexanoic acid/(g volatile suspended soilds (VSS),h) and 0.11 g acetic acid/(g VSS,h)), which suggests that the consumption of these majoritarian fatty acids was simultaneous. However, the determined consumption rate for butyric acid was approximately solely half of the values for hexanoic acid and acetic acid. The highest PHA yield obtained in the enrichment phase was 0.26 g PHB/g VFA.  In the production phase, the highest achieved PHA content was 31.4 % of VSS, which was obtained after five hours. Both PHB and polyhydroxyvalerate (PHV) were formed in this phase, even though the quantity of accumulated PHB dominated with its approximately 97 weight-%. / Polyhydroxialkanoater (PHA:er) är en grupp bioplaster som produceras med hjälp av mikroorganismer. De ackumuleras inuti granulater som finns i bakteriers cellcytoplasma, och används som en energireserv. PHA:er är dessutom fullständigt bionedbrytbara och biokompatibla biopolyestrar, vilket gör dem till lämpliga material att applicera inom medicinska preparat och för att ersätta konventionella petrokemiska plaster. Det är däremot inte ekonomiskt fördelaktigt att producera PHA:er än så länge, då det är fyra till nio gånger dyrare att producera än i jämförelse med att producera plaster från fossila bränslen. Ett tillvägagångssätt för att reducera priset är genom att applicera kolrikt avfall som råmaterial och en blandad kultur av mikroorganismer. Det var detta som tillämpades i detta examensarbete vid PHA produktionen. I denna studie syntetiserades PHA:er från en blandning av flyktiga fettsyror rik på hexansyra, som framställts av avfall genom anaerobisk digestion. Det experimentella arbetet delades in i två faser: en selektionsfas och en produktionsfas. Detta för att kunna erhålla högsta möjliga PHA innehåll. Den blandade kulturen av bakterier berikades under selektionsfasen genom applicering av alternerande svält/frossa cykler i 50 dagar. Produktionsfasen utfördes därefter i en så kallad ”fed-batch odling” för att ackumulera högsta möjliga kvantitet av PHA, med hjälp av den berikade kultur blandningen.  Selektionsfasen ansåg vara lyckad, då mängden ackumulerad PHA ökade med tiden. Endast polyhydroxibutyrat (PHB) producerades under berikelsefasen. De erhållna specifika konsumptionshastigheterna för hexansyra och ättiksyra var i samma storleksordning (0.10 g/(g flyktiga suspenderade ämnen, h) respektive 0.11 g/(g flyktiga suspenderade ämnen, h)), vilket tyder på att förbrukningen av dessa fettsyror skedde samtidigt. Konsumptionshastigheten för butansyra var däremot endast cirka hälften av hastigheterna för hexansyra samt ättiksyra. Det högsta PHA-utbytet beräknades till 0.26 g PHB/g flyktiga fettsyror. Det högsta PHA-innehållet som erhölls i produktionsfasen var 31.4 % av de flyktiga suspenderade ämnena, vilket uppmättes efter fem timmar. Både PHB och polyhydroxivalerat (PHV) bildades under denna fas, även om mängden ackumulerad PHB dominerade med 97 vikt-%. / <p>I och med COVID-19 presenterades examensarbetet via zoom</p> / Carbon Neutral Next Generation Wastewater Treatment Plants

Ce travail de thèse a eu pour objectif principal l'étude thermodynamique des changements métaboliques dans l'acidogénèse. L'acidogénèse est un procédé anaérobie à double intérêt qui en traitant des résidus organiques, permet de produire des composés chimiques comme l'hydrogène, l'éthanol et les acides organiques. Par conséquent, l'acidogénèse se place comme un procédé biotechnologique dans le concept de bioraffinerie. En outre, ce processus n'a pas besoin de conditions stériles d'opération et fonctionne sur une large gamme de pH. Ces changements métaboliques sont dépendants des modifications dans les conditions opératoires. Afin d'étudier ces changements métaboliques, des expériences basées sur des modifications du ciel gazeux du réacteur par introduction d'azote et sur des changements du pH, ont été menées. Un des résultats les plus intéressants a été l'augmentation du rendement de production d'hydrogène de 1 à 3,2 molH2/molglucose à pH 4,5 et débit de N2 de 58,4 L/d. Ce rendement est proche de la valeur théorique (4 molH2/molglucose). L'étude thermodynamique a permis d'expliquer les mécanismes métaboliques concernant l'hydrogène, dont la production importante, représentée par le rendement de 3,2 molH2/molglucose, est due à la réaction inverse H2/NAD+, qui est thermodynamiquement faisable à faibles pressions partielles d'hydrogène (par exemple 0,02 bar). En outre, les bas rendements en hydrogène ont été expliqués par l'action consommatrice d'hydrogène par la réaction d'homoacetogénèse. Cependant, le modèle n'a pas été capable d'expliquer les changements métaboliques de l'acétate, du butyrate et de l'éthanol lors de la fermentation acidogénique du glucose. / This thesis deals with thermodynamic based modelling of metabolic shifts during acidogenic fermentation. Acidogenic fermentation is an anaerobic process of double purpose: while treating organic residues, it produces chemical compounds, such as hydrogen, ethanol and organic acids. Therefore, acidogenic fermentation arises as an attractive biotechnology process towards the biorefinery concept. Moreover, this process does not need sterile operating conditions and works under a wide range of pH.Changes of operating conditions produce metabolic shifts, inducing variability on acidogenic product yields. In order to study these metabolic shifts, an experiment design was based on reactor headspace N2-flushing (gas phase) and pH step changes (liquid phase). A major result was the hydrogen yield increase from 1 to 3.2 (molH2/molglucose) at pH 4.5 and N2-flushing of 58.4 L/d. This yield is close to the theoretical acidogenic value (4 molH2/molglucose).The thermodynamic model, based on the assumption that acidogenic fermentation is characterised by limited energy available for biological process, allowed to explain the mechanisms that govern hydrogen metabolic shifts, showing that the synthesis of extra hydrogen, i.e. yield of 3.2 (molH2/molglucose), was due to reverse H2/NAD+ redox reaction, which is thermodynamically feasible at low hydrogen partial pressures (e.g. 0.02 bar). Moreover, low hydrogen yields were explained by the action of homoacetogenesis hydrogen consuming reaction. However, the model was not capable to explain the metabolic shifts of acetate, butyrate and ethanol on acidogenic glucose fermentation.

L’accumulation de biopolymère de réserve (PolyHydroxyAlcanoates ou PHA) par la souche Cupriavidus necator, à partir de substrats de type acides gras volatils (acide butyrique, acide propionique et acide acétique) a été étudiée. Elle est induite par une limitation phosphore. Les performances atteintes lors des cultures se situent parmi les meilleures de la littérature pour ce type de substrat : jusqu’à 66 g.L-1 de biomasse totale avec un pourcentage d’accumulation massique de 88% en PHB –PolyHydroxyButyrate- ou en PHB-co-HV -PolyHydroxyButyrate-co-HydroxyValerate- comportant jusqu’à 52% de motifs d’HV.Pour chaque source carbonée, une caractérisation cinétique et stœchiométrique de la souche a été réalisée en l’absence d’effets inhibiteurs dus aux substrats acides grâce à des cultures de type Fed-Batch avec des apports non limitants et non inhibiteurs en carbone. Il a été dégagé :- un taux de croissance maximal de la souche de 0,33 h-1 pour les trois acides étudiés- une relation entre vitesse spécifique de production de PHA et taux de croissance fixée par la disponibilité et les flux de production de NADPH2 avec un découplage inverse pour les taux de croissance supérieurs à 0,05 h-1 et un couplage partiel pour les taux de croissance inférieurs- un optimum de 0,35 Cmole.Cmole-1.h-1, associé à un taux de croissance de l’ordre de 0,05 h-1.- une amélioration de la production de PHB en termes de vitesses spécifiques mais également en termes de rendements si une faible croissance résiduelle est maintenueLa réponse de la souche à un excès de substrat acide a été caractérisée via l’étude de régimes transitoires induits par des pulses sur des cultures continues préalablement stabilisées en régime permanent. Il a été montré qu’en excès de phosphore, face à un brusque excès de substrat, la souche est incapable d’adapter rapidement son taux de croissance. L’excès est donc dirigé vers la production de PHA dont les voies sont plus rapidement mobilisables. En conditions limitantes de phosphore, le substrat excédentaire est utilisé pour la production de PHA. L’inhibition par les acides se traduit par une diminution des capacités de biosynthèse de la biomasse et des PHA entrainant une réduction de l’assimilation du carbone puis une diminution des rendements de conversion. D’autre part la sensibilité d’un système continu à un excès de substrat dépend du point de fonctionnement choisi : plus il est optimal en termes de vitesse, moins le système est robuste. L’acide propionique est très inhibiteur comparé aux autres acides étudiés (dès 3-4 mM contre 30-40 mM). Il n’agit pas simplement via une accumulation excessive dans le cytoplasme mais il exerce également une inhibition spécifique des voies métaboliques.Un antagonisme entre les substrats (acide acétique et butyrique) a été constaté et expliqué grâce à une analyse des flux métaboliques. L’acide acétique est assimilé préférentiellement pour produire la biomasse, l’énergie et les cofacteurs nécessaires à la production de PHA, alors que l’acide butyrique est utilisé pour la synthèse de PHB. La proportion maximale d’acide acétique admise dans l’alimentation en fonction des conditions fixées en régime permanent est calculée et peut être limitée à 40% du carbone.Enfin il a été déterminé que si une croissance résiduelle est assurée grâce à un apport en phosphore, le pourcentage maximal d’HV dans le polymère dépend du taux d’acide propionique dans l’alimentation et ne peux dépasser 33 ± 5% sur acide propionique pur. Par contre, si aucune croissance résiduelle n’est assurée, il est possible de convertir l’acide propionique en motifs d’HV uniquement / Reserve Biopolymer (PolyHydroxyAlkanoates or PHA) accumulation by the strain Cupriavidus necator, from Volatile Fatty Acids (VFA, like butyric acid, propionic acid and acetic acid) was investigated. This production is induced by a phosphorus limitation. For this type of substrates, performances reached during cultures are among the best listed in the literature: up to 66 g.L-1 of total biomass with 88% (w/w) of PHB –PolyHydroxyButyrate- or PHB-co-HV -PolyHydroxyButyrate-co-HydroxyValerate- with a HV content up to 52 Mole%.For each carbon source, kinetic and stoechiometric characterization has been carried out thanks to Fed-Batch cultures with non-limiting and non-inhibitory carbon feed. It has been established:- a maximal growth rate of 0,33 h-1 for the three acid investigated- a relationship between specific PHA production rate and growth rate which is set by the availability and production flux of NADPH2. For growth rate above 0,05 h-1, there is an inverse coupling. For growth rate under 0,05 h-1, there is a partial coupling.- an optimum of 0,35 Cmole.Cmole-1.h-1 is associated with a growth rate of 0,05 h-1.- if a low residual growth rate is maintained, an improvement of PHB production is recorded in terms of specific production rate and yieldsThe response of the strain to an excess of acid substrate was characterized through the investigation of transient state induced by pulsed addition of substrate during continuous cultures stabilized in steady state. It was shown that in excess of phosphorus, when there is a substrate excess, the strain is unable to quickly adapt its growth rate, so the excess is directed to PHA production whose ways seem to be more easily mobilized. Under phosphorus limitation, an excess of substrate is used for PHA production. Acid inhibition results in a decrease in biomass and PHA production capacity which leads to a decrease in carbon assimilation and conversion yields. The sensitivity of a continuous system to an excess of substrate depends on the chosen operating point: the more it is optimal in terms of specific production rate, the less the system is robust. Propionic acid is highly inhibitory compared to the other acids studied (from 3-4 mM versus 30-40 mM). It does not act only via an excessive accumulation in the cytoplasm but also exerts a specific inhibition of metabolic pathways.An antagonism between substrates (acetic and butyric acid) has been established and explained thanks to the Metabolic Flux Analysis. Acetic acid is preferentially used to produce biomass, energy and cofactors for PHA synthesis, whereas butyric acid is used to product PHB. According to the conditions set during steady state, maximal content of acetic acid admitted in the feed can be calculated. It can be limited to 40% of the carbon in the feed.Finally if a growth rate is maintained thanks to a phosphorus supply, the maximal HV content in polymer is function of propionic acid in the feed and cannot exceed 33 ± 5 Mole% on pure propionic acid. Conversely, if there is no residual growth, a total conversion of propionic acid into HV is allowed