O resíduo da primeira destilação do vinho, a vinhaça, destaca-se dentre os demais gerados na produção de etanol de cana-de-açúcar pelo seu grande volume e alta concentração de substâncias orgânicas. O tratamento anaeróbio desse efluente pode melhorar suas características físico-química (e.g. pH e DQO) além de produzir um combustível alternativo ao gás natural, o biogás. No entanto, apesar dos possíveis ganhos energéticos e ambientais, essa tecnologia apresenta dificuldades em se tornar viável no setor sucroenergético. Tendo em vista esse cenário, este trabalho propõe uma nova análise termodinâmica, baseada no método exergético, do potencial da vinhaça e do biogás provindo de seu tratamento. Para isso, modelou-se a digestão anaeróbia da vinhaça por meio do ADM1 (Anaerobic Digestion Model Nº1) e atualizou-se o cálculo da exergia química deste efluente. Assim, os resultados obtidos indicam que o tratamento anaeróbio pode recuperar uma significativa parcela da exergia descartada com a vinhaça (44-52% de 189-1529 kJ/l), dependendo da degradabilidade e concentração do material orgânico, bem como o regime de operação do reator anaeróbio. Nota-se também, que apesar de a digestão anaeróbia ser mais eficiente com maiores tempos de retenção hidráulica, é preferível maximizar o volume de vinhaça tratada em detrimento da qualidade de conversão. Além disso, o desempenho anual da geração de biogás também é afetado pelo seu processo de partida e pela sazonalidade da produção de etanol. Por outro lado, a planta de biogás promove maiores reduções de exergia destruída em comparação com a fertirrigação e a concentração de vinhaça. Possíveis integrações térmicas entre a planta de biogás e a unidade de concentração de vinhaça foram propostas e analisadas, atingindo melhores eficiências exergéticas e reduzidas demandas térmicas. De forma geral, esse estudo demonstra a aplicação do método exergético na valorização de resíduos orgânicos por meio da produção de biogás. / The residue of the first distillation of wine, vinasse, stands outs in the sugarcane ethanol production due to its huge volume and high concentration of organic substances. The anaerobic treatment of this effluent can enhance its physical-chemical characteristics (e. g. pH and COD) in addition to produce an alternative fuel to natural gas, the biogas. However, although there are possible gains in the energy and environmental aspects, this technology presents difficulties to become viable in Brazilian market. Therefore, this work proposes a new thermodynamic analysis, based on the exergy method, of the potential of vinasse and biogas produced in its anaerobic treatment. In order to accomplish this, the anaerobic digestion of vinasse was modeled with ADM1 (Anaerobic Digestion Model Nº1) and the chemical exergy calculation of this effluent was updated. Thus, the results obtained indicate that the anaerobic treatment can recover a significant part of vinasse exergy (44-52% of 189- 1529 kJ/l), depending on the digestible material concentration, as well as the anaerobic reactor operation. It also can be notice that, although anaerobic digestion be more efficient at higher retention times, it is desirable to maximize treated vinasse volume to the detriment of conversion quality. Furthermore, the biogas production yearly performance is also affected by the reactor start-up process and the ethanol production seasonality. On the other hand, the biogas plant promotes higher reductions of exergy destruction in comparison with fertirrigation and vinasse concentration. Possible thermal integrations between the biogas plant and the vinasse concentration plant were proposed and analyzed, reaching better exergy efficiencies and reduced thermal demand. In general, this study demonstrates the exergy method application in organic residues upgrade by biogas production.

O presente trabalho avaliou a geração de biogás em um reator de duas fases, operado em bateladas sequencias, com resíduos coletados no CEAGESP de São Paulo-SP. O reator com volume efetivo de 10,7 L, era composto por um biofiltro anaeróbio em sua parte inferior, seguido por um separador de gases e posteriormente por um depósito de resíduos a digerir na parte superior. O inóculo era proveniente do fundo de uma lagoa de lixiviados do aterro de São Carlos-SP. O experimento foi conduzido em temperatura controlada em 30 ± 2 ºC nas Etapas 1, 2 e 3. A Etapa 1 consistiu na ativação e adaptação da biomassa, utilizando-se etanol e posteriormente resíduo orgânico do CEAGESP. A Etapa 2 consistiu na operação anaeróbia do sistema com resíduo do CEAGESP com lodo já adaptado. Na Etapa 3, verificou-se o efeito da aeração no compartimento de resíduos. Na Etapa 4, avaliou-se a influência da temperatura na digestão anaeróbia e com isto foi possível a obtenção do coeficiente de Arrhenius. Na Etapa 5, comparou-se o sistema de duas fases com um segundo reator anaeróbio, com configuração parecida com a convencional. Os resultados obtidos de todas as etapas na geração de biogás no reator de duas fases foram de 0,44; 0,44; 0,47 m3 /Kg SV e as eficiências de remoção de Sólidos Voláteis foram de 82,1%; 84,5% e 84,8% nas Etapa 1, 2 e 3, respetivamente, com um tempo de ração de 14 d nas três etapas. As concentrações de metano foram de 68,4; 67,1 e 66,6%, respectivamente. Na Etapa 4, os resultados da geração de biogás foram de 0,36; 0,38; 0,41; 0,41 m3 biogás/Kg SV nas temperaturas 25,6 ºC; 28,9 ºC; 34,0 ºC e 38,1 ºC, respetivamente. Denotando que a temperatura é um fator importante na geração de biogás em digestão anaeróbia. No reator convencional, a geração de biogás foi de 0,32 m3 biogás/Kg SV. / The present work evaluated the biogas generation in a two-phase reactor, operated in batch sequences, with residues collected at CEAGESP in São Paulo-SP. The reactor with an effective volume of 10.7 L was composed of an anaerobic biofilter in its lower part, followed by a gas separator and later by a deposit of waste to digest in the upper part. The inoculum was from the bottom of a leachate pond in the São Carlos-SP landfill. The experiment was conducted at a temperature of 30 ± 2 º C in Steps 1, 2 and 3. Step 1, consisted of the activation and adaptation of the biomass using ethanol and then organic waste from CEAGESP. Step 2, consisted of the anaerobic operation of the system with residue of the CEAGESP with already adapted sludge. In Step 3, the effect of aeration on the waste compartment was verified. In Step 4, the influence of temperature on the anaerobic digestion was evaluated and with this it was possible to obtain the Arrhenius coefficient. In Step 5, the two-phase system was compared with a second anaerobic reactor, with the same configuration as conventional. The results of all stages in the biogas generation in the two-phase reactor were 0.44; 0.44; 0.47 m3 / Kg SV and the removal efficiencies of Volatile Solids were 82.1%; 84.5% and 84.8% in Step 1, 2 and 3 respectively; and a feed time were of 14 d in the three steps. Consequently, the percentage of methane was 68.4; 67.1 and 66.6%. In stage 4 the results in the biogas generation were 0.36; 0.38; 0.41; 0.41 m3 biogas / Kg SV at temperatures 25.6 ° C; 28.9 ° C; 34.0 ° C and 38.1 ° C respectively. In the conventional reactor the biogas generation was 0.32 m3 biogas / Kg SV.

Remotely located and sparsely populated areas often do not have access to an efficient grid connection for electricity supply. However, plenty of biomass is normally available in such areas. Instead of employing island solutions such as small diesel generators or large battery stacks for power provision, a flexibly operating microscale biomass power plant using locally available and renewable feedstock is not only an efficient way of providing those areas with competitive and reliable electricity, but also a step towards energy self sufficiency for a large share of areas worldwide, and towards mitigating the looming high costs of grid infrastructure upgrading and extension. A novel power plant design combining thermo chemical and biochemical biomass treatment was developed in this research. This system consists of a small scale gasifier and an anaerobic digester unit, both coupled to a gas storage system and a micro turbine as the generation unit. This design is suitable to continuously provide reliable electricity and accommodate fluctuating residential power demand, and it can be scaled to a level of around 100kWe, which is a fitting size for a group of residential customers, such as in a remote village. The project covers a review of available technology; the choice of suitable technology for such a plant and the design of the system; the set up of a detailed plant model in chemical engineering software; extensive simulation studies on the basis of load profiles to evaluate and optimise operation; and feedstock sourcing, efficiency and economic analyses. It will be shown that such a system is a feasible and economic solution for remote power supply, and that it can overcome many of the current obstacles of electrifying rural regions.

O presente trabalho avaliou a geração de biogás em um reator de duas fases, operado em bateladas sequencias, com resíduos coletados no CEAGESP de São Paulo-SP. O reator com volume efetivo de 10,7 L, era composto por um biofiltro anaeróbio em sua parte inferior, seguido por um separador de gases e posteriormente por um depósito de resíduos a digerir na parte superior. O inóculo era proveniente do fundo de uma lagoa de lixiviados do aterro de São Carlos-SP. O experimento foi conduzido em temperatura controlada em 30 ± 2 ºC nas Etapas 1, 2 e 3. A Etapa 1 consistiu na ativação e adaptação da biomassa, utilizando-se etanol e posteriormente resíduo orgânico do CEAGESP. A Etapa 2 consistiu na operação anaeróbia do sistema com resíduo do CEAGESP com lodo já adaptado. Na Etapa 3, verificou-se o efeito da aeração no compartimento de resíduos. Na Etapa 4, avaliou-se a influência da temperatura na digestão anaeróbia e com isto foi possível a obtenção do coeficiente de Arrhenius. Na Etapa 5, comparou-se o sistema de duas fases com um segundo reator anaeróbio, com configuração parecida com a convencional. Os resultados obtidos de todas as etapas na geração de biogás no reator de duas fases foram de 0,44; 0,44; 0,47 m3 /Kg SV e as eficiências de remoção de Sólidos Voláteis foram de 82,1%; 84,5% e 84,8% nas Etapa 1, 2 e 3, respetivamente, com um tempo de ração de 14 d nas três etapas. As concentrações de metano foram de 68,4; 67,1 e 66,6%, respectivamente. Na Etapa 4, os resultados da geração de biogás foram de 0,36; 0,38; 0,41; 0,41 m3 biogás/Kg SV nas temperaturas 25,6 ºC; 28,9 ºC; 34,0 ºC e 38,1 ºC, respetivamente. Denotando que a temperatura é um fator importante na geração de biogás em digestão anaeróbia. No reator convencional, a geração de biogás foi de 0,32 m3 biogás/Kg SV. / The present work evaluated the biogas generation in a two-phase reactor, operated in batch sequences, with residues collected at CEAGESP in São Paulo-SP. The reactor with an effective volume of 10.7 L was composed of an anaerobic biofilter in its lower part, followed by a gas separator and later by a deposit of waste to digest in the upper part. The inoculum was from the bottom of a leachate pond in the São Carlos-SP landfill. The experiment was conducted at a temperature of 30 ± 2 º C in Steps 1, 2 and 3. Step 1, consisted of the activation and adaptation of the biomass using ethanol and then organic waste from CEAGESP. Step 2, consisted of the anaerobic operation of the system with residue of the CEAGESP with already adapted sludge. In Step 3, the effect of aeration on the waste compartment was verified. In Step 4, the influence of temperature on the anaerobic digestion was evaluated and with this it was possible to obtain the Arrhenius coefficient. In Step 5, the two-phase system was compared with a second anaerobic reactor, with the same configuration as conventional. The results of all stages in the biogas generation in the two-phase reactor were 0.44; 0.44; 0.47 m3 / Kg SV and the removal efficiencies of Volatile Solids were 82.1%; 84.5% and 84.8% in Step 1, 2 and 3 respectively; and a feed time were of 14 d in the three steps. Consequently, the percentage of methane was 68.4; 67.1 and 66.6%. In stage 4 the results in the biogas generation were 0.36; 0.38; 0.41; 0.41 m3 biogas / Kg SV at temperatures 25.6 ° C; 28.9 ° C; 34.0 ° C and 38.1 ° C respectively. In the conventional reactor the biogas generation was 0.32 m3 biogas / Kg SV.

Textile is a global product used by all people in the world. These textiles after the use are thrown into the trash for incineration or land filling. However an efficient way that can be used to produce more energy, in an environmentally friendly process is anaerobic digestion. Waste textiles which contain cellulosic fibers (e.g. Cotton and viscose) can be converted to biogas. In this study, the performance of a two-stage anaerobic digestion process for biogas production from four different materials, including untreated jeans, treated jeans, cotton, and starch was studied. Starch was used as an easy-to-digest material to compare its digestion with that of cellulosic materials.The two-stage processes were composed of a CSTR (for hydrolysis) and a UASB (for methanogenisis) which were investigated in two different configurations, namely (closed and open systems). In the closed system, the outlet of UASB was completely returned back to the CSTR, while in the open system the UASB outlet was sent to sewage. In a stepwise progress, the OLR was aimed to increase from 2 to 20 g Vs per L per day along with reduction in hydraulic retention time from 10 days to 1 day.The results showed that the closed system was more stable when compared to the open system. The pre-treatment of jeans by NMMO helped to produce methane as that of cotton. The hydraulic retention time was decreased to less than 9 days for treated jeans and less than 5 days for starch. The overall methane yield at OLR of 4 gVS per L per day for starch and treated jeans was 98.5% and 97.4% in the closed system, whereas in the open system the yield was 77.0% and 35.5%, respectively.Another experiment was conducted to compare the performance of two-stage process with that of a single stage process of anaerobic digestion of textiles containing polyester and cotton or viscose. Viscose textiles produced more gas compared to the cotton textile; it may be due to the higher crystalline of cotton which makes it hard to be degraded by the microorganisms. Furthermore, two-stage process could able to produce more methane than the single stage process.The parameters like total solids, volatile solids, pH, gas production, gas composition, concentration of nutrients, and COD were also analyzed for both of the experiments.

La valorisation des déchets par digestion anaérobie conduit à la production d’un résidu, appelé digestat, qui est composé de la matière organique non biodégradée et présente une forte teneur en azote ammoniacal et organique. De par cette richesse en azote, les digestats présentent un intérêt grandissant pour la substitution aux engrais minéraux. L’objectif de cette thèse est de comprendre les transformations de l’azote en digestion anaérobie afin de prédire la qualité azotée des digestats. Cette compréhension des processus de transformation de l’azote ouvrira la possibilité de dimensionner et piloter le procédé de digestion anaérobie pour une substitution optimisée des engrais minéraux par les digestats. Pour cela, deux approches ont été développées: (i) une approche compréhensive centrée sur la compréhension de la bioaccessibilité de l’azote organique en lien avec sa biodégradabilité, et la compréhension des transformations de l’azote en digestion anaérobie en conditions de laboratoire et pilote; et ; (ii) une approche numérique où les processus identifiés ont été intégrés à des outils de modélisation à bases statistiques et biocinétiques permettant de prédire les propriétés azotées des digestats en fonction des cocktails de substrats et du temps de séjour dans le digesteur. / Energetic recovery of waste by anaerobic digestion leads to the production of a residue called digestate, which is composed of non-biodegraded organic matter and has a high content of ammoniacal and organic nitrogen. Due to this high nitrogen content, digestates are growing interest for the substitution of mineral fertilizers. The objective of this thesis is to understand the transformations of nitrogen that occur during anaerobic digestion in order to predict the nitrogen quality of digestates. This understanding of nitrogen transformation processes will allows the design and management of anaerobic digestion plants aiming at the optimization of the substitution of mineral fertilizers by digestates. To this end, two approaches were used in this work: (i) an experiment approach focused on the understanding of the bioaccessibility of organic nitrogen in relation to its biodegradability, and the understanding of the transformations of nitrogen in anaerobic digestion under laboratory and pilot conditions; and; (ii) a numerical approach where previously developed knowledge has been integrated in statistical and biokinetic modeling tools to predict the nitrogen properties of digestates according to substrate cocktails and residence time in the digester.

Com o aumento da produção de biodiesel para atender à legislação brasileira, está ocorrendo um aumento considerável na geração de glicerol, um resíduo líquido contendo cerca de 46 g\'CL POT.-\'/L e com elevada concentração de matéria orgânica (DQO média de 1.260 g/L). Apesar de ser bastante utilizado na indústria química, o teor de impurezas do glicerol oriundo de biodiesel limita o seu processamento industrial. Buscando agregar valor à este resíduo, utilizou-se um reator anaeróbio de manta de lodo e fluxo ascendente (UASB Upflow Anaerobic Sludge Blanket), em escala de laboratório (14,85 L de volume útil), para produzir metano visando geração de energia, tendo o glicerol residual como única fonte de substrato. Este glicerol residual foi obtido a partir da transesterificação de uma mistura de óleos de algodão e soja (2:3, v/v) em uma usina de biodiesel pertencente à Petrobrás S.A. Durante a operação, a COV foi aumentada gradualmente de 2,0 a 10,0 kgDQO/\'M POT.3\'.d e a diluição de glicerol residual no afluente foi reduzida de 1:1.500 até 1:5. O reator UASB foi capaz de remover, em média, 97,5% de matéria orgânica, apresentando 59% de \'CH IND.4\' no biogás, e relação AGV/Alc\'H\'CO IND.3\'POT.-\' abaixo de 0,3, mesmo com 14 g\'CL POT.-\'/L no interior do sistema. No entanto, foi necessário adicionar nutrientes em concentrações adequadas para evitar que o sistema entrasse em colapso. Os ensaios de toxicidade mostraram que o glicerol residual não é tóxico ao lodo anaeróbio, mas apresenta uma limitação inicial da metanogênese. O teste de biodegradabilidade anaeróbia indicou que o glicerol residual foi 65,9% biodegradável e o potencial de produção de metano alcançou 0,220 \'M POT.3\'CH IND.4\'/kg Glicerol. / The Brazilian legislation demands the use of biodiesel mixed with diesel in an increasing rate. This raise on biodiesel production implies also on an increase on generation of glycerol, which is a liquid or semi-solid waste with high concentration of salts (approximately 46.1 g\'CL POT.-\'/L) and organic matter (1260 gCOD/L in average). Despite being widely used in chemical industry, the residual glycerol contains impurities that limit its industrial processing. In order to add value to this residue, an upflow anaerobic sludge blanket reactor (UASB) at laboratory scale (14.85 L of working volume), fed with glycerol generated on biodiesel industry, was used to produce biogas, which can be used for power generation via methane. This wasted glycerin was produced by the transesterification process of a mixture of the cottonseed oil and soybean oil (2:3, v:v) in a Petrobras S/A biodiesel plant. During operation, the organic loading rate (OLR) was gradually increased from 2.0 to 10.0 kgCOD/\'M POT.3\'.d., and the dilution of residual glycerol in the influent was reduced from 1:1500 to 1:5. The UASB reactor was able to remove 97.5% of the organic matter, producing biogas with 59% of \'CH IND.4\', and VFA/Alk\'H\'CO IND.3\'POT.-\' ratio below 0.3, even with a very high concentration of chloride in the bulk liquid (14 g\'CL POT.-\'/L). However, it was necessary to add nutrients in adequate concentrations to prevent the system from collapsing. The toxicity tests showed that the residual glycerol used in the research was not toxic to the anaerobic sludge. The anaerobic biodegradability test indicated that the residual glycerol was 65.9% biodegradable and the biochemical methane production potential was 0.220 \'M POT.3\'CH IND.4\'/kg Glycerol.

This thesis reports on investigations that have contributed to an advancement in the applied and fundamental understanding on how the nature, related storage and processing of digested sewage sludge can influence polymer conditioning and dewatering. The work concentrated more specifically on evaluating the impact of thermal hydrolysis as a pre-treatment to anaerobic digestion (AD) of mainly secondary sewage sludges (Advanced AD, AAD plants) in comparison with conventional mesophilic AD (CMAD) on conditioning and dewatering of the digestate, as this knowledge seemed to be lacking for an AAD technology that is increasingly being implemented. An additional contribution to knowledge from this study relates to the evaluation of how polymer conditioning and dewatering of digested sludges could be monitored using rheometric measurements. It was concluded that digested sludge biofloc characteristics (size, shear viscosity and organic matter composition) affected the most the conditioning and dewatering results but these varied depending on the process conditions i.e. AAD versus CMAD and digestate handling conditions. The reduction in particle size and shear viscosity (η[0.1 s-1]) per g Total Solids as well as the increased solubilization of protein, organically bound nitrogen and chemical oxygen demand of the digestates which contributed to the increased conditioning requirements affected also the dewatering rate and the strength of the flocs produced after conditioning. The changes in the digested sludge biofloc characteristics were detected by rheometric measurements which were well correlated with changes in organic matter composition and polymer conditioning requirements (r of 0.9 and 0.8). It was proposed that the variations in η[0.1 s-1] and organic matter content such as soluble protein could be used to predict polymer dose requirements to achieve good filterability (R2 of 0.7; significance F and p < 0.05). Future work is however required in order to consolidate these findings by monitoring conditioning, dewatering and η[0.1 s-1] of the digestate at full scale.

Anaerobic digestion is a key energy and resource recovery technology. This work investigated potential organic waste resources to co-digest with household food waste (HFW) to stabilise the process and future-proof feedstock availability. This included novel feedstock macroalgae (seaweed) waste (SW). Hydrothermal (autoclave) pretreatment was also investigated to optimise energy recovery from HFW and SW. Preliminary experiments investigated the behaviour of HFW co-digested with either a green waste (GW) or paper waste (PW), using a batch-test laboratory scale and systematic approach with a revised waste mixture preparation method. Following preliminary trials, the co-digestion of HFW/SW was investigated using an air-dried SW mixture. Batch experiments to determine the biomethane potential (BMP) at different ratios of HFW to SW were set up. Co-digesting HFW and SW at ratio 90:10 (d.w.) achieved a BMP similar to HFW alone (252±13 and 251±1 cm3 g-1 VS, respectively), and a peak methane yield for HFW:SW (90:10) at day 12 of 69±3% compared to a peak methane yield for HFW at day 19 of 70±3%. Addition of SW optimised the C/N ratio, increased concentrations of essential micronutrients and produced an overall increase in reaction kinetics. Concentrations of SW ≥25%, associated with high sulphur levels, reduced final methane productivity. Analysis of the macroalgae strains L. digitata, U. lactuca and F. serratus from the SW mixture was carried out to compare mono-digestion and co-digestion with HFW at a 90:10 ratio and the effect of autoclave pretreatment at 136°C. Co-digestion had a positive impact on methane yields for U. lactuca and F. serratus, whilst autoclave pretreatment had no significant impact on the SW strains When results were modelled for a 320 m3 anaerobic digester treating 8m3 feed per day the theoretical energy balance showed that optimal energy production from pretreated HFW at 8.09 GJ/day respectively could be achieved. To verify the suitability of using macroalgae, known to readily uptake polycyclic aromatic hydrocarbons (PAH), toxicity tests were used to determine the impact of phenanthrene sorbed by U. lactuca on the AD process. Despite U. lactuca’s ability to biosorb phenanthrene in under 2 hours, no impact on the AD process was observed. Overall, results of this study demonstrated that co-digestion of HFW and SW, at batch laboratory scale, provide a viable and sustainable waste revalorisation solution. In addition, low temperature autoclave pretreatment increased methane production (p=0.002) from the AD of HFW.

Lignocellulosic biomasses are considered promising feedstocks for the next generation of biofuels and chemicals; however, the recalcitrance of lignocellulose remains a barrier to its utilisation over conventional sources. Pyrolysis is the heating of biomass to several hundred degrees Celsius in the absence of oxygen, which can thermally depolymerise lignocellulose. Products of pyrolysis are a solid biochar, liquid bio-oil and syngas. Biochar has roles in both carbon sequestration and soil amendment however bio-oil has no defined use, despite a high concentration of fermentable sugars. Bio-oil is a complex organic microemulsion with a host of biocatalyst inhibitors that makes its microbial degradation a challenge. In this work, the use of aerobic cultures using microbial communities isolated from natural environments saw limited potential; however, the use of anaerobic digestion (AD) successfully generated a higher volume of biogas from reactors with bio-oil than controls. Biogas yield test reactors were set up with anaerobic digestate from a wastewater treatment plant as the substrate for degradation and conversion of bio-oils. Next-generation 16S rRNA gene sequencing was utilised to characterise the communities in the reactors while the ultrahigh resolution mass spectrometry technique of Fourier transform ion cyclotron resonance (FT-ICR) was used for characterisation of the chemical changes occurring during AD. Both sets of high-resolution data were additionally combined for multivariate analysis and modelling of the microbial genera that correlated best with the changes in digestate chemistry. This represents a novel analysis method for the microbial degradation of complex organic products. Bio-oil from common lignocellulosic feedstock was the most easily degradable by the AD communities, with significant inhibition observed when bio-oils from anaerobic digestate and macroalgae were used. Additionally it was found that the inclusion of biochars that were pre-incubated in anaerobic digestate prior to use in AD were capable of significantly reducing the lag time observed for biogas production in bio-oil-supplemented reactors. The addition of biochars that were not pre-incubated had no effect on biogas production. Specific inhibition of methanogenesis was also capable of causing the digestates to accumulate volatile fatty acids (VFAs) as a product of greater value than biogas. Scale-up experiments will be required to confirm the precise practicalities of the addition of bio-oil to AD as well as to establish the potential for isolation and purification of VFAs.