Today's society is facing major challenges. In order to reduce the climate impact fossil fuels should be replaced with fuels that do not contribute to the greenhouse effect. The growing population generates organic waste originating from industry and households so called organic fraction of municipal solid waste (OFMSW). Through anaerobic digestion, waste can be utilized to produce energy-rich methane gas. In this way, waste can be a resource instead of a burden on society. The purpose of this project is to investigate the methane yield of source-sorted organic fraction of municipal solid waste (SS-OFMSW) pretreated with screw crush technology and methane yield at the co-digestion of food waste and biosludge from paper mills. SS-OFMSW which is either pre-treated in a screw crusher or a Food Waste Mill and a mixture of SS-OFMSW and biosludge from paper mills digested in a semi - continuous wet process under mesophilic conditions with a retention time of 20 days. Screw crush technique gave a slurry with a methane yield of about 440-490 mL / g VS, which was slightly higher than the yield of 300-350 mL / g VS from the slurry pretreated with Food Waste Mill. The methane concentration was slightly higher for slurry pretreated with Food Waste Mill, 74% in average compared with 68% for slurry pretreated with screw crush. Biosludge from paper mills is an organic waste that can be digested in order to produce biogas. The sludge is poor in nutrients and methane yield at individual anaerobic digestion of paper mill sludge is relatively low. In this study, biosludge was co-digested with SS-OFMSW. The mixture with the proportions 1:1 by g VS gave a methane yield of about 420-480 mL / g VS which is higher than the constituent substrates digested separately. Co-digestion gave a methane concentration at 80% which is also higher than at the individual anaerobic digestion of substrates.

Anaerobic digestion is a sustainable and economically feasible waste management technology, which lowers the emission of greenhouse gases (GHGs), decreases the soil and water pollution, and reduces the dependence on fossil fuels. The present thesis investigates the anaerobic digestion of waste from food-processing industries, including citrus wastes (CWs) from juice processing and chicken feather from poultry slaughterhouses. Juice processing industries generate 15–25 million tons of citrus wastes every year. Utilization of CWs is not yet resolved, since drying or incineration processes are costly, due to the high moisture content; and biological processes are hindered by its peel oil content, primarily the D-limonene. Anaerobic digestion of untreated CWs consequently results in process failure because of the inhibiting effect of the produced and accumulated VFAs. The current thesis involves the development of a steam explosion pretreatment step. The methane yield increased by 426 % to 0.537 Nm3/kg VS by employing the steam explosion treatment at 150 °C for 20 min, which opened up the compact structure of the CWs and removed 94 % of the D-limonene. The developed process enables a production of 104 m3 methane and 8.4 L limonene from one ton of fresh CWs. Poultry slaughterhouses generate a significant amount of feather every year. Feathers are basically composed of keratin, an extremely strong and resistible structural protein. Methane yield from feather is low, around 0.18 Nm3/kg VS, which corresponds to only one third of the theoretical yield. In the present study, chemical, enzymatic and biological pretreatment methods were investigated to improve the biogas yield of feather waste. Chemical pretreatment with Ca(OH)2 under relatively mild conditions (0.1 g Ca(OH)2/g TSfeather, 100 °C, 30 min) improved the methane yield to 0.40 Nm3/kg VS, corresponding to 80 % of the theoretical yield. However, prior to digestion, the calcium needs to be removed. Enzymatic pretreatment with an alkaline endopeptidase, Savinase®, also increased the methane yield up to 0.40 Nm3/kg VS. Direct enzyme addition to the digester was tested and proved successful, making this process economically more feasible, since no additional pretreatment step is needed. For biological pretreatment, a recombinant Bacillus megaterium strain holding a high keratinase activity was developed. The new strain was able to degrade the feather keratin which resulted in an increase in the methane yield by 122 % during the following anaerobic digestion. / <p>Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 1 juni 2012, klockan 10.00 i KA-salen, Kemigården 4, Göteborg.</p>

Biogas production from organic materials can be used as a renewable vehicle fuel, provide heat and generate electricity and can thereby reduce the greenhouse gas emissions. This thesis focuses on the biogas production based on lignocelluloses. There is an abundant availability of lignocelluloses, constituting 50% of the total biomass worldwide. However, the biomass recalcitrance limits the microbial degradation as well as the biogas production from these types of materials. In the present work different pretreatment methods have been performed in order to decrease the biomass recalcitrance and improve the biogas production. Steam explosion pretreatment, together with the addition of sodium hydroxide and hydrogen peroxide, has been performed on lignocellulosic-rich paper tube residuals. The pretreatment has resulted in methane yields of up to 493 NmL/gVS, which is an increase by 107% compared with untreated material. Furthermore, the use of an organic solvent, N-methylmorpholine-N-oxide (NMMO), was evaluated as a pretreatment method for spruce (both chips and milled), rice straw, and triticale straw. The NMMO pretreatment resulted in 202, 395, 328, and 362 NmL CH4/g carbohydrates produced of these substrates, respectively, corresponding to an increase of between 400-1,200% compared with the untreated version of the same material. Moreover, the paper tube residuals have been co-digested with an unstable nitrogen-rich substrate mixture, mainly based on municipal solid waste. The addition of the lignocellulosic-rich paper tubes in a co-digestion process showed stabilizing effects and prevented the accumulation of volatile fatty acids with a subsequent reactor failure. Additionally, synergistic effects have been found leading to between 15-33% higher methane yields when paper tubes were added to the co-digestion process compared with the yields calculated from the methane potentials of the two substrates. Substrate characterization analysis can be used to study the changes on the lignocellulosic components after the pretreatment, relating the changes to the performance in the anaerobic digestion. Increased accessible surface area, measured by the Simons’ stain and the enzymatic adsorption methods, as well as decreased crystallinity, determined by using the Fourier Transform Infrared Spectroscopy, can all be linked to improved biogas production after pretreatment. Finally, the NMMO pretreatment on forest residues has been financially evaluated for an industrial scale process design. The base case that was evaluated simulated a case where pretreated forest residues were co-digested with the organic fraction of municipal solid waste to obtain optimal nutritional balance for the anaerobic digestion. This process has been found to be economically feasible with an internal rate of return of 20.7%. / <p>Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 24 maj 2013, klockan 10.00 i KA,Kemigården 4, Göteborg</p>

Este trabalho apresenta uma avaliação da produção de metano em um reator anaeróbio operado em batelada sequencial com biomassa imobilizada em suporte inerte (AnSBBR) pela codigestão de vinhaça de cana-de-açúcar e soro de queijo em condições mesofílicas. A avaliação é realizada com base na influência da variação dos aspectos operacionais de estratégia de alimentação (batelada ou batelada alimentada), interação entre tempo de ciclo (8, 6 ou 4 h) e concentração afluente (5000, 3750 ou 2500 mgDQO.L-1), carga orgânica volumétrica aplicada (5, 7,5, 10 ou 15 gDQO.L-1.d-1) e temperatura (25, 30 e 35&#186;C) sobre a estabilidade e desempenho do sistema. O AnSBBR com recirculação da fase líquida e volume reacional de 3,0 L foi operado por 186 dias, sendo o afluente para todos os ensaios composto por 75 % vinhaça e 25 % soro (massa/volume) e suplementado com bicarbonato de sódio. Nas condições operadas, o sistema demonstrou flexibilidade quanto à estratégia de alimentação, porém a redução do tempo de ciclo e da concentração afluente, para a mesma carga, resultou em menores produções de metano. Por outro lado, o aumento da carga orgânica, até o valor de 15 gDQO.L-1.d-1, favoreceu o processo, aumentando o rendimento de metano por DQO removida e a produtividade. A redução da temperatura de 30 para 25 &#186;C resultou na queda do desempenho, porém às temperaturas de 30 e 35 &#186;C foram obtidos resultados similares. O melhor desempenho foi alcançado a uma carga aplicada de 15,27 gDQO.L-1.d-1, tempo de ciclo de 8 horas, operação em batelada alimentada e temperatura de 30 &#186;C. Nessas condições, o sistema atingiu remoção de DQO solúvel de 88,8 %, produtividade de metano de 208,5 molCH4.m-3.d-1 (equivalente a 4672 CNTP-mLCH4.L-1.d-1), rendimento de metano por DQO removida de 15,76 mmolCH4.gDQO-1 e composição de metano de 72% no biogás. O ajuste do modelo cinético demonstrou preferência pela rota hidrogenotrófica na metanogênese em todos os ensaios. Na aproximação em escala plena para o cenário de usina de etanol de cana-de-açúcar com produção de etanol de 150.896 m3.ano-1 foi estimada uma geração de energia de 25.544 MWh.mês-1. / This paper presents an assessment of the methane production in an anaerobic sequencing batch biofilm reactor (AnSBBR) by co-digestion of sugarcane vinasse and cheese whey at mesophilic conditions. The assessment is based on the influence of modifying the operational aspects of feed strategy (batch or fed-batch), interaction between cycle time (8, 6 or 4 h) and influent concentration (5000, 3750 or 2500 mgCOD.L-1), applied volumetric organic load (5, 7.5, 10 or 15 gCOD.L-1.d-1) and temperature (25, 30 and 35 &#186;C) over the system stability and performance. The AnSBBR with recirculation of the liquid phase and 3.0 L of liquid medium was operated for 186 days, with influent composition for all assays of 75 % vinasse and 25 % whey (mass/volume), also supplemented with sodium bicarbonate. At the operated conditions, the system showed flexibility with regards to the feed strategy, but the reduction of cycle time and influent concentration, for the same organic load, resulted in lower methane productions. On the other hand, increasing organic load, to the value of 15 gCOD.L-1.d-1, favored the process, increasing methane yield and productivity. Temperature reduction from 30 to 25 &#186;C resulted in performance loss, although at 30 and 35&#186;C it was achieved similar results. The best performance was achieved at an applied organic load of 15.27 gCOD.L-1.d-1, cycle time of 8 hours, fed batch operation and temperature of 30 &#186;C. The system achieved soluble COD removal efficiency of 88.8 %, methane productivity of 208.5 gCOD.L-1.d-1 (equal to 4672 STP-mLCH4.L-1.d-1), methane yield per removed organic matter of 15.76 mmolCH4.gCOD-1 and methane composition of 72% of the biogas. The kinetic model fit showed preference for the hydrogenotrophic route in the methanogenesis. At the full scale approximation considering a scenario with a sugarcane ethanol plant with ethanol production of 150,896 m3.year-1 it was estimated an energy production of 25,544 MWh.month-1.

Slaughterhouse waste (SB) has high potential to be utilized in anaerobic digestion due to its high protein and lipid content. However, these are also the limiting factors of system stability. Thus, co-digestion of slaughterhouse waste with other agro-industrial residues (manure (M), various crops (VC) and municipal solid waste (MSW)) was introduced in this study to overcome this problem. The main objective of the work was to determine the operating parameters and the methane yield in semi-continuous co-digestion of slaughterhouse waste with other agro-industrial waste streams. Four continuously stirring tank reactors (CSTRs) with different substrates and mixtures (SB, SB:M, SB:VC and SB:VC:MSW) were started up operating with hydraulic retention time (HRT) of 25 days in thermophilic conditions. The highest organic loading rates which could be achieved were 0.9 g VS/L·d in digestion of SB and 1.5 g VS/L·d for the co-digestion mixtures. In these cases, average methane yields of 300, 510, 587 and 426 ml/g VS were obtained from the digestion of SB, and the co-digestion of SB:M, SB:VC and SB:VC: MSW, respectively, with methane contents in the biogas of 60-85%. The highest average methane yield of 587 ml/g VS was found in co-digestion of SB:VC, which was in accordance with the value of 592 ml/g VS detected during the batch digestion of the same mixture. Moreover, batch assays with different substrates as well as 11 different mixtures of those were also set up to investigate the methane potential and the effect of second feeding. The results showed that the co-digestion of SB:VC, SB:VC:MSW and SB:M could provide high methane potentials, where the highest methane yields of 592, 522 and 521 ml/g VS, respectively were obtained. Moreover, increasing, similar or decreasing methane yields were determined from the second feeding depending on the substrates and substrate mixtures used. / Program: MSc in Resource Recovery - Sustainable Engineering

Nitrogen Inhibition during an anaerobic co-digestion process was studied in this work.The substrate and inoculum used were obtained from a thermophilic biogas plant Sobacken,situated in Borås, Sweden. The batch experiments have been carried out in triplicate reactorswith different concentrations of ammonia ranging from 2400mg/l to 3400mg/l. The batchexperiment was working well for the all the concentrations of ammonia investigated. Theaverage methane yield was around 0.65 Nm3 CH4/kgVS for all the reactors. The laboratorywork has been further proceeded with a continuous process having two reactors working inparallel. Reactor 1 containing only substrate and the Reactor 2 contain substrate with surplusammonia added to make final concentration of 3400mg/l. The reactors were operated atorganic loading rate (OLR) of 3.3gVS/l/day and hydraulic retention time (HRT) of 20 days.Both reactors worked well for 29 days. During a period of an initial stable operation, theaverage methane production of Reactor 1 was 0.59 Nm3CH4/kgVS/day and for Reactor 2 theproduction rate was 0.56 Nm3CH4/kgVS/day. Then Reactor 1 showed a steady decrease in pHand methane production, while Reactor 2 showed stable operation for a few days longer withdecreasing pH and methane production only from day 36. The composition of substrate wasnot optimal; therefore the inhibition level of ammonium could not be determined.

Made available in DSpace on 2017-07-10T15:14:38Z (GMT). No. of bitstreams: 1 Claudinei.pdf: 2960967 bytes, checksum: 9d19185b777a99f89f11718066e20baa (MD5) Previous issue date: 2016-04-04 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The use of alternative energy sources is driven by the aim of minimizing environmental degradation in order to avoid that natural resources are depleted and slow the advance of global warming caused by emissions of greenhouse gases. Much has been researched about new energy sources, among which may be cited as the main: solar energy, wind energy, hydropower and biomass. The biogas from the biological treatment is distinguished by its increasing use to be a source of clean energy with a great social, financial and environmental return to humanity. To enhance this production of biogas, area researchers see performing various combinations, to evaluate or how best to combine any type of waste and succeed in increasing biogas production, consequently use in the energy sector. Thus, this work presents the objective analysis of the Total Solids removal rate, using the APHA methodology, 2012; Analysis of Higher Calorific Value using calorimeter; Analyze Biogas composition, by a Gas Chromatograph and analysis of biogas production using swine manure, silage medium grain corn, sorghum and pasture ground ruziziensis following a Factorial Planning 23, resulting in higher cumulative production to combination of swine wastewater 90% + Brachiária ruziziensis 10%, with 37.2 liters of biogas in seven weeks. Analyzing - the potential production per kilogram of matter, the highest result was the combination of ARS (80%) + Silage corn (10%) + Brachiária (10%), with 22 L.kg-1. Upon analyzing the result of production per kilogram of total solids, the result of the combination is greater production ARS (90%) + Brachiaria (10%), with approximately 561 L.Kg ST-1. / A utilização de fontes alternativas de energia é impulsionada pelo intuito de minimizar a degradação ambiental de forma a evitar que os recursos naturais se esgotem e diminuir o avanço do aquecimento global causado pelas emissões dos gases de efeito estufa. Muito se tem pesquisado a respeito de novas fontes energéticas, dentre elas podem ser citadas como principais: energia solar, energia eólica, energia hídrica e biomassa. O biogás, proveniente do tratamento biológico, se destaca pelo seu uso crescente por ser uma fonte de energia limpa com um grande retorno social, financeiro e ambiental para humanidade. Para potencializar essa produção de biogás, pesquisadores da área veem realizando diversas combinações, para avaliar qual ou quais as melhores formas de combinar algum tipo de resíduo e obter sucesso no aumento da produção de biogás, consequentemente utilização no setor energético. Desta forma, este trabalho apresenta por objetivo analise da taxa de remoção de Sólidos Totais, utilizando a metodologia de APHA, 2012; Análise de Poder Calorífico Superior, utilizando Calorímetro; Analise de Composição do Biogás, por meio de um Cromatógrafo Gasoso e analise da produção de biogás utilizando dejeto suíno, silagem de milho de meio grão, sorgo sacarino e braquiária Ruziziensis triturados, seguindo um Planejamento Fatorial 23, tendo como resultado de maior produção acumulada à combinação de Água Residuária de Suinocultura 90% + Braquiária Ruziziensis 10%, com 37,2 litros de biogás em sete semanas. Analisando se o potencial de produção por quilo de matéria, o maior resultado foi à combinação de ARS (80%) + Silagem Milho (10%) + Braquiária (10%), com 22 L.kg-1. Ao ser analisado o resultado de produção por quilo de Sólidos Totais, o resultado de maior produção é na combinação ARS (90%) + Braquiária (10%), com aproximadamente 561 L.Kg-1 ST.

This study aimed at seeking for the solution to recover the energy from agriculture waste in the Mekong Delta, Vietnam. The spent mushroom compost - a residue from the mushroom growing - was chosen for co-digestion with pig manure in anaerobic batch and semi-continuous experiments. The results showed that in case of spent mushroom compost made up 75% of the mixed substrate, the gained biogas volume was not significantly different compared to the treatment fed solely with 100% pig manure. The average produced biogas was 4.1 L×day-1 in the experimental conditions. The semi-continuous experiments remained in good operation up to the 90th day of the fermentation without any special agitating method application. The methane contents in both experiments were around 60%, which was significantly suitable for energy purposes. These results confirm that spent mushroom compost is possibly an acceptable material for energy recovery in the anaerobic fermentation process. / Nghiên cứu này nhằm tìm kiếm giải pháp thu hồi năng lượng từ chất thải nông nghiệp tại ĐBSCL, Việt Nam. Rơm sau ủ nấm - phế phẩm sau khi trồng nấm rơm - được chọn để ủ kết hợp với phân heo trong các bộ ủ yếm khí theo mẻ và bán liên tục. Kết quả cho thấy nếu phối trộn đến 75% rơm sau ủ nấm trong nguyên liệu ủ, tổng lượng khí thu được không khác biệt đáng kể so với thí nghiệm ủ 100% phân heo. Trong điều kiện thí nghiệm, lượng khí thu được trung bình là 4.1 L.ngày-1. Thí nghiệm ủ bán liên tục vẫn vận hành tốt ở ngày thứ 90 mặc dù mẻ ủ không được khuấy đảo. Hàm lượng khí mê-tan đo được chiếm khoảng 60% hoàn toàn có thể sử dụng cho các nhu cầu về năng lượng. Những kết quả thí nghiệm khẳng định có thể sử dụng rơm sau ủ nấm để thu hồi năng lượng thông qua quá trình ủ yếm khí kết hợp.

The main objective of this thesis was to study the anaerobic digestion (AD) of wastewater from a chicken processing facility and of crude glycerol from local biodiesel operations. The AD of these substrates was conducted in bench-scale reactors operated in the batch mode at 35°C. The secondary objective was to evaluate two sources of glycerol as co-substrates for AD to determine if different processing methods for the glycerol had an effect on CH₄ production. The biogas yields were higher for co-digestion than for digestion of wastewater alone, with average yields at 1 atmosphere and 0°C of 0.555 and 0.540 L (g VS added)⁻¹, respectively. Another set of results showed that the glycerol from an on-farm biodiesel operation had a CH₄ yield of 0.702 L (g VS added)⁻¹, and the glycerol from an industrial/commercial biodiesel operation had a CH₄ yield of 0.375 L (g VS added)⁻¹. Therefore, the farm glycerol likely had more carbon content than industrial glycerol. It was believed that the farm glycerol had more impurities, such as free fatty acids, biodiesel and methanol. In conclusion, anaerobic co-digestion of chicken processing wastewater and crude glycerol was successfully applied to produce biogas rich in CH₄.

Fat, oil, and grease residues, food particles, solids and some kitchen wastewaters are collected in grease traps which are separate from the municipal wastewater stream. Grease traps are emptied periodically and grease trap waste (GTW) is hauled for treatment. This dissertation focuses on anaerobic co-digestion of un-dewatered (raw) GTW with municipal wastewater treatment sludge (MWS) at wastewater treatment plants. In particular, this research focuses on the biochemical methane potential of un-dewatered GTW as well as the stability and performance of anaerobic co-digestion of MWS and un-dewatered GTW. A set of modified biochemical methane potential tests was performed to determine the methane potential of un-dewatered GTW under mesophilic conditions (35 °C). Methane potential of un-dewatered GTW in this study was 606 mL CH₄/g VS [subscript added] which is less than previously reported methane potentials of 845 - 1050 mL CH₄/g VS [subscript added] for concentrated/dewatered GTW. However, the methane potential of un-dewatered GTW (606 mL CH₄/g VS [subscript added]) was more than two times greater than the 223 mL CH₄/g VS [subscript added] reported for MWS digestion alone. A comprehensive study was performed to determine the stability and performance of anaerobic co-digestion of MWS with un-dewatered GTW as a function of increasing GTW feed ratios. The performance of two semi-continuously fed anaerobic digesters at 35 °C was evaluated as a function of increasing GTW feed ratios. Anaerobic co-digestion of MWS with un-dewatered GTW at a 46% GTW feed ratio (on a volatile solids basis) resulted in a 67% increase in methane production and a 26% increase in volatile solids reduction compared to anaerobic digestion of MWS alone. On the other hand, anaerobic co-digestion of un-dewatered GTW resulted in a higher inhibition threshold (46% on VS basis) than that of dewatered GTW. These results indicate that using un-dewatered GTW instead of dewatered GTW can reduce the inhibition risk of anaerobic co-digestion of MWS and GTW. Recovery of the anaerobic digesters following upset conditions was also evaluated and semi-continuous feed of digester effluent into upset digesters yielded of the biogas production level of the undisrupted digestion. Finally, a mathematical model was used to describe the relationship between methane potential and GTW feed ratio on a VS basis. The results of this research can be used to predict methane production and identify suitable GTW feeding ratios for successful co-digestion of un-dewatered GTW and MWS. / text