Made available in DSpace on 2017-05-12T14:48:45Z (GMT). No. of bitstreams: 1 Tese Osvaldo.pdf: 5754399 bytes, checksum: 701637b7657c10259c85108bc616425b (MD5) Previous issue date: 2012-05-15 / The cassava starch industries generate daily a large volume of wastewater effluent that, stabilized in ponds, waste its biogas energy and pollute the atmosphere. To contribute with the reversion of this reality, this manipueira treatment research in one phase anaerobic horizontal pilot reactor with continuous feeding was developed. The reactor was implanted at a starch factory, Toledo, PR, which processes 160 ton cassava day-1 and originates 800 m3 of cassava wastewater. The biomass agitation was obtained by biogas recirculation, pumped by radial compressor, being the support medium set up with 15 x 4 cm bamboo pieces. The cassava wastewater, in natura, flowed by a sand and clay separating chamber, feeding the reactor with volume measured by an hydrometer. The experimental design was a completely randomized design, with the responses submitted to multivariate analysis and to statistical quality control through R 13.0 and Minitab 15.1.0.0 softwares, respectively. The average organic loadings in chemical oxygen demand (COD) were 0.556; 0.670; 0.678; 0.770 and 0.902 g L-1; and in volatile solids (VS) 0.659; 0.608; 0.570; 0.761 and 0.816 g L-1 at the hydraulic retention times (HRT) of 13.0; 11.5; 10.0; 7.0 and 7.0 days. The average reductions for COD, at the same order that the HRTs, were 88; 80; 88; 67 and 70% and for VS 76; 77; 65; 61 and 53%. The biogas productions relatively to COD consumed were 0.368; 0.795; 0.891; 0.907 and 0.626 Lg-1, relatively to VS consumed were 0.524; 0.930; 1.757; 0.952 and 0.981 Lg-1 and volumetrically 0.131; 0.330; 0.430; 0.374 and 0.377 L L-1 d-1, with an average methane content of 56%. The 10.0 days HRT was evaluated with an average temperature of 27.7 °C and the others with temperatures ranging from 21.2 to 23.5 °C. The agitation efficiency was proven as it increased the reactor s performance, in spite of a 2.3 °C average reduction at the temperature. The stability indicators pH and volatile acidity/total alkalinity (VA/TA) relation remained between 6.51 to 7.45 and 0.11 to 0.82, respectively. Although the relation VA/TA has presented risk values, the reactor remained stable, possibly due to the support medium presence / As fecularias produzem diariamente um grande volume de manipueira, que, estabilizada em lagoas, desperdiça a energia do biogás e polui a atmosfera. Para contribuir com a reversão dessa realidade, desenvolveu-se esta pesquisa de tratamento de manipueira em reator anaeróbio horizontal piloto com alimentação contínua. O reator foi implantado numa fecularia, em Toledo PR, que processa 160 t de mandioca dia-1 e gera 800 m3 de manipueira. A agitação da biomassa foi realizada por recirculação de biogás bombeado por compressor radial e o meio suporte foi montado com peças de bambu de 15 x 4 cm. A manipueira, in natura, fluiu por uma caixa separadora de areia e argila e alimentou o reator com volume medido por hidrômetro. O delineamento experimental foi inteiramente casualizado, com respostas submetidas à análise multivariada que permitiram avaliar as correlações entre as variaveis e ao controle estatístico da qualidade através dos programas R 13.0 e Minitab 15.0, respectivamente. As cargas orgânicas médias em demanda química de oxigênio (DQO) aplicadas foram de 0,556; 0,670; 0,678; 0,770 e 0,902 g L-1 e em sólidos voláteis (SV) de 0,659; 0,608; 0,570; 0,761 e 0,816 g L-1 nos tempos de retenção hidráulica (TRH) de 13,0; 11,5; 10,0; 7,0 e 7,0 dias, respectivamente, sendo o último TRH com agitação. As reduções médias de DQO, na ordem de apresentação dos TRHs, foram de 88; 80; 88; 67 e 70% e de SV 76; 77; 65; 61 e 53%. As produções de biogás por DQOc foram de 0,368; 0,795; 0,891; 0,907 e 0,626 Lg-1, por SVc de 0,524; 0,930; 1,757; 0,952 e 0,981 Lg-1 e volumétrica de 0,131; 0,330; 0,430; 0,374 e 0,377 L L-1 d-1, com média de metano em 56%. O TRH de 10,0 dias foi avaliado com temperatura média mais elevada, de 27,7 °C, e os demais com temperatura variando entre 21,2 a 23,5 °C. A eficiência do agitador foi comprovada ao melhorar o desempenho do reator, apesar da redução média de 2,3 °C na temperatura. Os indicadores de estabilidade, pH e relação acidez volátil/alcalinidade total (AV/AT), mantiveram médias entre 6,51 a 7,45 e 0,11 a 0,82, respectivamente. Apesar da relação AV/AT ter apresentado valores de risco, o reator permaneceu estável, o que pode ser devido à presença do meio suporte

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.

Swine production represents approximately 40% of the world's meat production, and swine wastes contain high concentrations of organic matter, nitrogen (N) and phosphorus (P). Swine production is intensifying as meat demand increases and concentrated animal feeding operations (CAFOs) are becoming increasingly common, making it difficult to treat the waste generated. A system for holistic treatment of swine waste produced in CAFOs was investigated in this study that sustainably generates energy and recovers N and P as saleable fertilizers. The system uses anaerobic digestion (AD) for methane production and solids stabilization, followed by precipitation of struvite (MgNH4PO4*6H2O) and recovery of N by ion exchange onto natural zeolites. This process is expected to mitigate both eutrophication of receiving waters and greenhouse-gas emissions while generating products that meet agronomic nutrient demands; however, the economic and environmental sustainability remains unknown. The objectives of this study were to: (1) evaluate water quality and the fate of nutrients and ions in each step in the proposed system through pilot and bench scale experiments, (2) evaluate content/quality of struvite precipitates formed in wastewater treatment processes, (3) assess basic composition of zeolite materials that are being considered for use as IX materials, (4) quantify the environmental impact of the proposed system, and (5) estimate the economic benefits and costs of the proposed system. The results of a bench scale evaluation of the system show that although water quality greatly improves throughout the treatment process, the effluent water quality has high concentrations of COD (2,803 mg O2/L) and E. coli (106.3 CFU/100ml). This limits reuse options for the reclaimed water, however a variety of on-farm applications may be suitable. During struvite precipitation, the recovery efficiency of SRP was 87% (60 mg/L recovered); however, although measurements that take into account P in suspended solids show a lower recovery efficiency, they also show higher mass recovery (77% efficiency, 66 mg/L recovered). N recovery during struvite precipitation showed a similar trend, with 49% of TN and 7% of NH4-N being recovered. Struvite recovery can only occur from NH4-N and soluble reactive P. The additional recovery observed is likely due to adsorption of the nutrients onto the precipitate. Therefore, to accurately measure and report recovery, measurements of N and P that take into account suspended solids should be used. In most wastes, magnesium is the limiting constituent for struvite formation, but for swine AD effluents, P is the limiting constituent. Therefore, a higher soluble P concentration would increase recovery potential. The majority of the remaining N and P as well as a significant amount of potassium (K) were recovered during IX. Six struvites from commercial processes as well as our bench-scale experiments were assessed and compared by X-ray diffraction, SEM imaging, and SEM-EDX scans. All samples were confirmed as struvite by XRD, however they varied widely in crystal size and shape. The elemental composition of the samples was similar; however, struvite formed from phosphate mining waste had higher amounts Mg and P, indicating more pure struvite formation. The presence of impurities in some samples was likely due to the reactor design and solids separation methods. XRD was also used to confirm the identity of zeolites. Three clinoptilolites had similar crystal size and elemental composition except for Zeosand [reg] which showed a surface roughness, which likely contributes to higher cation exchange capacity. Chabazite has smaller crystal size and larger pores than clinoptilolite, which also likely contributes to its higher capacity. Life cycle assessment (LCA) was used to evaluate the environmental sustainability of the system and the results suggested that environmental benefits were provided across almost all impact categories. Two alternatives for raising the pH in struvite precipitation (NaOH addition vs. aeration) and two alternatives for zeolite IX materials (chabazite vs. clinoptilolite) were assessed, but there were negligible differences between alternatives. The system was also assessed at a medium and large scale, and the large scale was more environmentally friendly across all categories. Operational impacts were significantly greater than construction impacts; therefore, the environmental impact of the system can be accurately assessed by only including operation. A life cycle cost assessment (LCCA) was also performed on the system and showed a payback period of 39 years for a medium sized system and 15 years for a large size. This, however, is when compared to a "business-as-usual" scenario and does not consider renewable energy credits or government grants. Furthermore, although a larger system is more economically beneficial, this must be balanced with quality of animal care. From a cost standpoint, IX recovery using chabazite is not recommended and struvite precipitation using aeration is more economically beneficial than NaOH addition.

Organics recycling is increasing in New England as multiple states have enacted laws to divert organic materials, including food scraps and food processing residuals, away from landfills. Anaerobic digesters on dairy farms represent an attractive approach to food waste recycling because existing infrastructure is in place and co-digestion of dairy manure with food waste can increase renewable biogas production. In addition, anaerobic digestion results in effluents that can be separated into solid and liquid residual materials, or 'digestates'. Screw-press separated solids consist of lignocellulosic biomass resistant to microbial degradation during anaerobic digestion. These separated solids are typically recycled on farms as animal bedding before returning to the digester, whereas remaining liquid digestates are typically spread as fertilizer for nearby feed crops or pasture fields. Within this model, anaerobic digestion is not a nutrient management solution and repeated land application of digestate nutrients can create eutrophication risk over time. Alternative models are needed where digestate materials are converted into valuable products to be sold off-farm, enabling the removal of nutrients to help meet nutrient management goals. In this thesis, I address two research questions related to the pursuit of such alternative models. First, how do physicochemical characteristics of digestate materials vary across full-scale systems in the region, including systems with and without food waste as a substantial proportion of feedstock, and how do these variations affect the potential for conversion of digestates into valuable products (e.g., soil amendments)? Second, can separated digestate solids be used for commercial cultivation of gourmet oyster mushrooms (Pleurotus ostreatus) to produce food for human consumption, providing synchronous nutrient recovery and food production? Results from my first research chapter indicate that increasing food waste inputs (and thus diversification of feedstock recipes) will likely increase the variability of some solid and liquid digestate characteristics and can result in greater contamination with synthetic particles, with implications for nutrient recovery efforts and associated products. My second research chapter shows that screw-press separated digestate solids can offset non-local substrate ingredients to a degree while achieving oyster mushroom yields comparable to commercial recipes. Furthermore, this strategy could divert nutrients away from land adjacent to digesters and directly into safe, nutritious, protein-rich food for humans, while also producing a useful spent mushroom substrate product.

<p>This paper reports on environmental impacts and health hazards as a result from inadequate management of organic household waste in developing countries. It gives details of water and soil contamination, air pollution and spread of diseases through expanding breeding grounds for pathogens, vectors and rodents. To manage this waste flow sustainably, decentralised composting and anaerobic digestions technologies have been studied to give an overall picture of existing appropriate technologies, including: windrow, box/bin/barrel, THM, aerated static pile, in-vessel, vermi, ARTI compact biogas digester and BARC’S NISARG-RUNA. Comparing different technologies showed that it is crucial to consider local conditions and markets when choosing which method to implement. However, the manual composting methods: windrow/box/bin/barrel, THM and vermi, are more likely to be appropriate in regard to current conditions in developing countries. A comparison between the environmental impacts of anaerobic digestion and composting did not result in a clear indication of which technology is most favourable. However, in the literature studied, biogas production showed an overall better energy balance, and composting a better result regarding nutrient recycling and xenobiotic compounds. In terms of the mitigation effect on global warming, the results varied essentially depending on the technology used and its loss of methane during the biogas production process. Finally, this paper investigates common constraints for implementation of the above-mentioned technologies, as well as recommendations for future projects. The study of general constraints revealed the need for directing attention to education, key consequences and benefits, co-operation, exchange of knowledge and bottom-up driving forces, for sustainable and successful implementation of organic household waste management practices in developing countries.</p>

This paper reports on environmental impacts and health hazards as a result from inadequate management of organic household waste in developing countries. It gives details of water and soil contamination, air pollution and spread of diseases through expanding breeding grounds for pathogens, vectors and rodents. To manage this waste flow sustainably, decentralised composting and anaerobic digestions technologies have been studied to give an overall picture of existing appropriate technologies, including: windrow, box/bin/barrel, THM, aerated static pile, in-vessel, vermi, ARTI compact biogas digester and BARC’S NISARG-RUNA. Comparing different technologies showed that it is crucial to consider local conditions and markets when choosing which method to implement. However, the manual composting methods: windrow/box/bin/barrel, THM and vermi, are more likely to be appropriate in regard to current conditions in developing countries. A comparison between the environmental impacts of anaerobic digestion and composting did not result in a clear indication of which technology is most favourable. However, in the literature studied, biogas production showed an overall better energy balance, and composting a better result regarding nutrient recycling and xenobiotic compounds. In terms of the mitigation effect on global warming, the results varied essentially depending on the technology used and its loss of methane during the biogas production process. Finally, this paper investigates common constraints for implementation of the above-mentioned technologies, as well as recommendations for future projects. The study of general constraints revealed the need for directing attention to education, key consequences and benefits, co-operation, exchange of knowledge and bottom-up driving forces, for sustainable and successful implementation of organic household waste management practices in developing countries.

The finite amount of energy carriers affects all of us. It is important to utilize all available sources and to find new sources of energy. The confectionery industry generates both solid and liquid waste during the production of confectioneries, which could be utilized as a substrate for biogas production. However, problems might arise during the biogas process since these kinds of waste are very rich in carbohydrates. The initial breakdown of the substrate would probably cause an accumulation of fermentation products such as volatile fatty acids (VFA) and a low pH. A solution to this might be to use a two-stage process. The first stage would be a pre-fermentation that should be optimized for production of fermentation products such as ethanol and VFA. The aim of this master thesis is to evaluate the biogas potential of confectionery waste products. The confectionery waste products are evaluated using a continuous two-stage process, batch experiments and theoretical calculations of the methane potential. The potential from process wastewater was examined. Depending on COD reduction for a reactor and COD content of process wastewater, an annual amount of 75 000 m3 or of 857 000 m3 of process wastewater is necessary to produce enough biogas for a gas engine to continuously convert the biogas to electricity. A batch experiment evaluating the methane production potential of nine different confectionery waste products from a large confectionery industry gave a range of 430 - 690 NmL/g VS, which is relatively high. A continuous experiment in two lab-scale reactors with a HRT of two days worked satisfactory. The gas production was stable periodically with a carbon dioxide content above 60%. The pH was low (3.4 - 3.6) throughout the experiment for one of the reactors. However, addition of digester sludge from a methane-producing reactor towards the end of the experiment resulted in a higher pH and more VFA available for utilization in the second stage. The main fermentation products were: acetic acid, lactic acid, ethanol and carbon dioxide. A second batch experiment showed that the methane potential was not affected by pre-fermentation. A carbon balance calculation of the process indicates that 57% of the ingoing organic matter is fermented within only two days and ends up in the known fermentation products. The study shows that confectionery waste products are well suited for two-stage anaerobic digestion. / Den ändliga mängden av energibärare påverkar oss alla. Det är därför viktigt att utnyttja alla tillgängliga men även att finna nya energibärare. Konfektyrindustrin generar restprodukter (avfall) både i fast och flytande form, vilka båda kan utnyttjas för produktion av biogas. Det kan dock uppstå problem i biogasprocessen eftersom dessa innehåller en stor mängd kolhydrater. Den initiala nedbrytningen kan ge upphov till en ackumulering av VFA och ett lågt pH. En lösning på detta problem kan vara att använda en två-stegs process. Första steget är en för-fermentering, som ska optimeras för att producera fermentationsprodukter så som etanol och VFA. Syftet med detta arbete är att utvärdera biogaspotentialen från konfektyrrestprodukter genom att använda en kontinuerlig två-stegs process, batchförsök och teoretiska beräkningar av metanpotentialen. Potentialen undersöktes från processvatten. Beroende på COD reduktion i en reaktor och COD innehåll i processvatten, är en årlig mängd av 75 000 m3 eller av 857 000 m3 processvatten nödvändig för att producera en tillräcklig mängd biogas så att en gasmotor kontinuerligt kan omvandla biogasen till elektricitet. Ett batchförsök med nio olika restprodukter från en storskalig konfektyrproducent visade en relativt hög metanpotential (430 - 690 NmL/g VS). Ett kontinuerligt reaktorexperiment genomfördes i laboratorieskala med två reaktorer, där uppehållstiden var två dagar. De två för-fermenteringsreaktorerna presterade tillfredsställande. Gasproduktionen var periodvis stabil med en koldioxidhalt över 60%. pH var lågt (3,4 och 3,6) genom hela experimentet för en av reaktorerna. För den andra reaktorn gjordes tillsatser av reaktormaterial från en metanproducerande reaktor i slutet av experimentet. Dessa tillsatser ökade pH och totalmängden av VFA, som kan utnyttjas i det andra steget. Huvudfermentationsprodukterna är acetat, laktat, etanol och koldioxid. Ytterligare batchförsök visade att för-fermentation inte verkar påverka metanpotentialen för konfektyrrestprodukter. En kolbalans av processen indikerar att 57% av ingående kol återfinns i de kända fermentationsprodukterna inom två dagar. Studiens resultat visar att avfallsprodukter från konfektyrindustrin lämpar sig väl för två-stegs anaerob rötning.

Med ett växande energibehov i världen, sinande energikällor i form av fossila bränslen och en miljö som vi under en längre tid har förorenat behövs det nya energiformer som är mer långsiktiga och framförallt miljövänliga. En sådan energiform är biogas. Biogasprocessen är dock inte helt optimerad. Flera av de substrat som används idag tar lång tid att röta och bryts bara ner till viss del i processen eller innehåller onödigt mycket vatten, vilket ger höga transportkostnader. Med syfte att göra biogasprocessen mer ekonomisk lönsam utvärderas i denna rapport på uppdrag från E.ON några olika förbehandlingstekniker: Ångexplosion, extrusion, avvattning och kalkbehandling. Förhoppningen är att dessa ska kunna öka lönsamheten för storskalig biogasproduktion och kanske möjliggöra biogasproduktion från tidigare obrukbara substrat som fjädrar och halm.  För att jämföra och utvärdera förbehandlingsteknikerna utfördes batchrötningsförsök i 330 ml flaskor med obehandlade och förbehandlade substrat. De flesta förbehandle substraten gav snabbare nedbrytning och några gav även högre metanutbyte än de obehandlade. Fjädrar och halm, som från början hade ett lågt utbyte, påverkades mest av förbehandlingen. Ångexploderade fjädrar gav efter 44 dagars rötning 141% högre metanutbyte och extruderad halm gav 22% högre metanutbyte än obehandlad.  För ekonomiska beräkningarna användes en referensanläggning med en förutbestämd substratmix: 12500 ton majs och 11500 ton hästgödsel. Att tillgå för referensanläggningen finns dessutom fjädrar. Cambis THP-anläggning för ångexplosion visade sig vara alldeles för dyr för referensanläggningen. En THP-anläggning kräver en större biogasanläggning där en större mängd svårnedbrytbara substrat rötas för att bli lönsam. En extruder skulle kunna vara lönsam för för refernsanläggningen om hästgödseln som de har tillgång till innehåller halm som strömaterial. En investering i en extruder bara för att förbehandla majsensilage visade sig inte lönsam.  Avvattning av gödsel gav signifikant lägre utbyte av biogas per torrvikt men signifikant högre utbyte per våtvikt. Avvattningsutrustningen från Splitvision, som testades, var för dyr för att bli lönsam. Först när gården låg 4 mil från biogasanläggningen blev det billigare att avvattna gödsel och transportera den jämfört med att transportera den obehandlad. Andra avvattningsutrustningar i studien var billigare i drift så det finns möjligheter att tekniken kan bli lönsam med någon av dessa. / The world needs new energy sources that are durable for long time and which not affect the environment negatively. Biogas fulfills those demands. The biogas process is however not completely optimized. Several of the substrates used today for biogas production are slowly degraded and only partly digested in the process. Other substrates consist of unnecessarily much water which makes transportation costly. To optimize the process and make the biogas process more profitable, several pretreatment techniques are evaluated by direction of E.ON in this report: steam explosion, extrusion, lime treatment and dewatering. The hope is that one of those could increase the profitability and hopefully also enable substrates that not are working today like feathers and straw. To compare and evaluate the different pretreatment batch digester, experiments were carried out during 31-44 days for untreated and pretreated substrates. Most pretreated substrates were faster degraded than untreated and some also gave a higher methane yield. Chicken waste feathers and wheat straw, which had low methane yields untreated, were affected most by pretreatment. Steam exploded feathers gave after 44 days of digestion 141% higher methane yield and extruded straw gave 22% higher methane yield than untreated samples of the same substrate. A reference plant with a substrate mixture of 12500 tonnes of maize silage and 11500 tons of horsemanure annually was used to make economical calculations. Additionally, chicken waste feathers waste could be included. Obtainable for the reference plant were also chicken waste feathers. Steam explosion appeared to be too expensive for a plant in the size of the reference plant. Its large capacity could probably make it profitable for a much larger biogas plant running on a lot of hard digestible substrates. An extruder could be a profitable investment for the reference plant if the plant gets horse manure with straw as bedding material. To just use the extruder to pretreat maize silage could not make the investment profitable. Dewatering of manure gave significantly lower methane yield per dry weight but significantly higher methane yield per wet weight. The increase in methane yield per wet weight makes the substrate better for transportation. The dewatering equipment from Splitvision tried in this study had too high operational costs and was too expensive to make dewatering particularly profitable. Only when the farm was situated farther away than 40km from the biogas plant it was cheaper to dewater the manure before transport than to transport the manure without any pretreatment. Other dewatering equipments evaluated in this study had much lower operational costs and among those an equipment that makes dewatering profitable might therefore be found. The world needs new energy sources that are durable for long time and which not affect the environment negatively. Biogas fulfills those demands. The biogas process is however not completely optimized. Several of the substrates used today for biogas production are slowly degraded and only partly digested in the process. Other substrates consist of unnecessarily much water which makes transportation costly. To optimize the process and make the biogas process more profitable, several pretreatment techniques are evaluated by direction of E.ON in this report: steam explosion, extrusion, lime treatment and dewatering. The hope is that one of those could increase the profitability and hopefully also enable substrates that not are working today like feathers and straw. To compare and evaluate the different pretreatment batch digester, experiments were carried out during 31-44 days for untreated and pretreated substrates. Most pretreated substrates were faster degraded than untreated and some also gave a higher methane yield. Chicken waste feathers and wheat straw, which had low methane yields untreated, were affected most by pretreatment. Steam exploded feathers gave after 44 days of digestion 141% higher methane yield and extruded straw gave 22% higher methane yield than untreated samples of the same substrate. A reference plant with a substrate mixture of 12500 tonnes of maize silage and 11500 tons of horsemanure annually was used to make economical calculations. Additionally, chicken waste feathers waste could be included. Obtainable for the reference plant were also chicken waste feathers. Steam explosion appeared to be too expensive for a plant in the size of the reference plant. Its large capacity could probably make it profitable for a much larger biogas plant running on a lot of hard digestible substrates. An extruder could be a profitable investment for the reference plant if the plant gets horse manure with straw as bedding material. To just use the extruder to pretreat maize silage could not make the investment profitable. Dewatering of manure gave significantly lower methane yield per dry weight but significantly higher methane yield per wet weight. The increase in methane yield per wet weight makes the substrate better for transportation. The dewatering equipment from Splitvision tried in this study had too high operational costs and was too expensive to make dewatering particularly profitable. Only when the farm was situated farther away than 40km from the biogas plant it was cheaper to dewater the manure before transport than to transport the manure without any pretreatment. Other dewatering equipments evaluated in this study had much lower operational costs and among those an equipment that makes dewatering profitable might therefore be found.

Ultrasonic sludge disintegration &ndash / the most commonly used mechanical pretreatment method- enables the occurrence of cavitation bubbles to extract intracellular material from the cell into aqueous phase. However, there is a lack of information on the volatile solids loading on the anaerobic digestion process performance of ultrasonically treated sludge. In this thesis work, the effect of sonication on disintegration of waste activated sludge (WAS) and an important parameter digester F/M (food to microorganism) ratio on ultrasonically treated WAS were investigated. First, preliminary studies were conducted. It was obtained that when the sonication power and time increased, soluble COD in the supernatant increased as well. Then, batch anaerobic digestion tests were conducted. Effect of F/M ratio in the digesters by using sonicated sludges at different powers was analyzed. For the sludge sonicated at high power, the methane content increased up to 55.1 % at F/M ratio of 10 compared to untreated sludge. On the other hand, methane generation rate slowed down with the increase in F/M ratio. Moreover, 10 % and 15 % increase in the destruction of MLVSS and total COD content was observed for sonicated sludges compared to the untreated sludges, respectively. In summary, both the sonication as a pretreatment method and the increase in digester F/M ratio increased the biogas production and the solids reduction during anaerobic digestion prosess. These results may have important implications for the operation of full scale systems in terms of system efficiency and operation.

Biomass-fuelled proton exchange membrane fuel cells (PEMFCs) offer asolution for replacing fossil fuel for hydrogen production. Through using thebiomass-derived hydrogen as fuel, PEMFCs may become an efficient andsustainable energy system for small and medium-sized enterprises. The aim ofthis thesis is to evaluate the performance and potential applications of biomassfuelledPEMFC systems which are designed to convert biomass to electricity andheat. Biomass-fuelled PEMFC systems are simulated by Aspen plus based ondata collected from experiments and literature.The impact of the quality of the hydrogen-rich gas, anode stoichiometry, CH4content in the biogas and CH4 conversion rate on the performance of the PEMFCis investigated. Also, pinch technology is used to optimize the heat exchangernetwork to improve the power generation and thermal efficiency.For liquid and solid biomass, anaerobic digestion (AD) and gasification (GF),respectively, are relatively viable and developed conversion technologies. ForAD-PEMFC, a steam reformer is also needed to convert biogas to hydrogen-richgas. For 100 kWe generation, the GF-PEMFC system yields a good technicalperformance with 20 % electrical efficiency and 57 % thermal efficiency,whereas the AD-PEMFC system only has 9 % electrical efficiency and 13 %thermal efficiency. This low efficiency is due to the low efficiency of theanaerobic digester (AD) and the high internal heat consumption of the AD andthe steam reformer (SR). For the environmental aspects, the GF-PEMFC systemhas a high CO2 emissions offset factor and the AD-PEMFC system has anefficient land-use.The applications of the biomass-fuelled PEMFC systems are investigated on adairy farm and an olive oil plant. For the dairy farm, manure is used as feedstockto generate biogas through anaerobic digestion. A PEMFC qualified for 40 %electrical efficiency may generate 360 MWh electricity and 680 MWh heat peryear to make a dairy farm with 300 milked cows self-sufficient in a sustainableway. A PEMFC-CHP system designed for an olive oil plant generating annual 50000 m3 solid olive mill waste (SOMW) and 9 000 m3 olive mill waste water(OMW) is simulated based on experimental data from the Biogas2PEM-FCproject1. After the optimization of the heat exchanger network, the PEMFC-CHP  system can generate 194 kW electricity which corresponds to 62 % of the totalelectricity demand of the olive oil plant.The economic performance of the PEMFC and biogas-fuelled PEMFC areassessed roughly including capital, operation &amp; maintenance (O&amp;M) costs of thebiogas plant and the PEMFC-CHP, the cost of heat and electricity, and the valueof the digestate as fertilizer. / <p>QC 20151109</p>