This master’s thesis deals with design of mechanical screen cleaning machine for wastewater treatment plant, which will be placed in 800 mm wide and 1 850 mm deep intake canal. Thesis includes research of produced systems, construction design, drive unit design and other necessary strength and technical calculations. Thesis is supplemented by drawing of machine and its details.

Unrestricted use of reclaimed secondary effluents for irrigation is a major goal in countries suffering from water shortage. Reverse osmosis desalination is used to provide high quality waters with reduced salinity. In order to allow water production with high economic efficiency, fouling in the membrane installation needs to be minimized. Biofouling, caused by microorganisms synthesizing high-molecular biofilms, is of major concern. Biofouling reduces the water production rate and thus increases the costs of the process. Deeper knowledge on its formation and its impact on membrane performance is needed. This is relevant especially for large-scale treatment plants, where process conditions change over length and time and influencing factors on fouling formation occur in combination. Thus, in the present thesis a membrane test cell was developed which enables the investigation of biofouling under validated, representative conditions of full-scale modules. Biofouling was studied in order to determine its impact on membrane performance. Also, appropriate, cost-effective pre-treatment prior to the reverse osmosis process minimizes fouling. Therefore, biofiltration and its suitability as stand-alone pre-treatment was studied when reusing secondary effluents with reverse osmosis. The developed membrane test cell of 1 m length can be assembled with further test cells to simulate a spiral wound module alone, as well as several modules in series in a pressure pipe. The test set-up enables the systematic study of fouling formation integrative over the full length of industrial spiral wound modules. All performance parameters (feed channel pressure drop, permeability/flux, and salt passage) can be monitored over the full length and locally connected to accumulated foulants (non-destructive fouling diagnosis). Validation studies demonstrated that the hydraulic conditions (relationship between pressure drop and flow velocity, as well as the flow profile) are exactly as in real spiral wound modules. Each test cell is a representative, validated system of full-scale dimensions and hydraulics. It was further found that for fouling formation investigations, feed spacers with the same thickness as the feed channel height need to be used. In this way, accurate experimental measurements, especially of feed channel pressure drop, are ensured. With the developed test cells, the impact of biofouling on membrane performance was determined under conditions similar to practice. Biofouling resulted in a decline of all membrane performance parameters. Feed channel pressure drop was affected earliest and most severely, indicating its suitability as a sensitive biofouling monitoring parameter. Salt rejection was moderately impacted by biofouling and influenced by several process parameters, reducing its applicability as monitoring parameter. It was further found, that most biofilm accumulated in the lead parts of the membrane test cells with a declining gradient towards the tail sections. The gradient of biofouling over the length of the membrane installation was directly referred to the declining availability of easily assimilable substrate. It emphasizes the importance to reduce the concentration of biodegradable nutrients in the feed to the membrane installation as suitable strategy to restrict biofouling. The high amount of biofilm deposits in the lead parts caused feed channel pressure drop increase over the lead test cell and affected negatively the performance of the downstream test cells: The tail test cells showed a moderate decline for the permeability (flux) and salt rejection. Biofiltration improved the quality of secondary effluents as tertiary treatment. It successfully reduced the load of substances (microbes, dissolved organic matter, biopolymers, particles) reportedly contributing to fouling of subsequent membrane processes. Especially biopolymers of secondary effluents, which are major membrane foulants, were identified to be completely biodegradable. The biopolymers were estimated to be of colloidal size. Yet, the removal of these organics was suggested to be completely caused by biodegradation; neither filtration nor adsorption mechanisms played a role to retain biopolymers and dissolved organic carbon within the biofilter. However, a combined study of biofiltration and reverse osmosis revealed, that the improving effect of biofiltration as pre-treatment on membrane performance was lower than expected. Although, both biofouling and organic fouling were reduced on the reverse osmosis membrane, only marginal improvement on performance parameters was found. The adsorption of small non-biodegradable substances on the membrane as an organic fouling layer in the early stages of the process, as well as the difference in fouling layer composition were probably reasons for the findings. Thus, the successful application of biofiltration as pre-treatment is highly depending on the feed water source and the foulant layer formation. For the present case biofiltration as stand-alone pre-treatment is not recommended; a combination of biofiltration with subsequent e.g. flocculation and UF could be more beneficial.

Return liquor from thermal hydrolysis process (THP) can significantly add to the nitrogen load of a wastewater treatment plant (WWTP) and introduce UV quenching substances to the wastewater stream when recycled. While there are mature technologies in place to handle the inorganic nitrogen produced due to the thermal pretreatment, organic nitrogen remains a parameter of concern for utilities employing THP pretreatment. The impact of operating conditions of the THP on dissolved organic nitrogen (DON) and UV absorbance in return liquor was investigated. Operating conditions studied were (1) operating temperature (2) solids retention time (SRT) in the anaerobic digester (3) THP flash pressure (4) the effect of co-digestion of sewage sludge with food waste and, (5) polymer conditioning. Operating temperature and polymer dose had the most significant impact on DON and UV quenching. It was found that an increase in operating temperature resulted in an increase in DON, which was primarily contributed by the hydrophilic fraction. An increase in temperature also resulted in increased UV254 absorbance. However, this trend was not linear and the increase was more pronounced when the temperature was increased from 150 C to 170 C. Increasing flash pressure from 25 psi to 45 psi did not have a significant impact on the return liquor. However, increasing the flash pressure to 75 psi increased the DON and UV254 absorbing compounds. Co-digesting the sludge with food waste resulted in a slight increase in DON and a decrease in dissolved organic carbon (DOC) and UV quenching compounds. Increasing the SRT from 10 days to 15 days resulted in a slight decrease in DON but did not have any impact on UV254 absorbance. Overall, it can be concluded that optimizing operating conditions of thermal hydrolysis process can result in decreased DON and UV quenching compounds in the recycle stream. / Master of Science

The study was aimed to investigate the effect of corn stalk pre-treatment duration on biogas production when cow dung and corn stalk was co-digested in an anaerobic digestion. Corn stalks were pre-treated in different durations: 2-days, 5-days, and 8-days before being added to cow dung into anaerobic co-digesters. The experiments were set up randomly by using triplicate batch anaerobic apparatus in 21 L containers that run in 60-days. The mixing ratio between a corn stalk and cow dung was 50%: 50% (based on the volatile solid value of each material), but corn stalk was cut into small pieces with around 10 cm length, while the cow dung was air dried. The results of the study indicated that all operation parameters such as temperature, pH, and alkalinity in the anaerobic batch were suitable for biogas production. The results showed that there was a significant improvement in total gas produced in the pre-treated 5-days treatment (206.4±8.4 L) compared to 2-days (153.4±9.6 L), and 8-days ones (174±11.1 L). The biogas yield of the pretreated 2-days, 5-days, and 8-days treatments were 392.7±9.8 L/kg VSfermented, 469.8±10.1 L/kg VSfermented and 497.1±13.3 L/kg VSfermented, respectively, that was not significantly different (5%). In all treatments, low concentration of methane in the beginning phase had been observed but increased and reached the optimum value for energy use after 10 days. The result of the study showed that it is preferable to have 5-days pre-treatment of corn stalk before the corn stalk is loaded to an anaerobic digester in combination with cow dung. / Nghiên cứu này nhằm đánh giá ảnh hưởng của thời gian xử lý thân cây bắp lên năng suất sinh khí khi ủ phối trộn phân bò và thân cây bắp trong điều kiện yếm khí. Ba mức thời gian xử lý thân cây bắp được chọn là 2 ngày, 5 ngày, và 8 ngày. Các thí nghiệm được bố trí ngẫu nhiên trong các bình ủ yếm khí theo mẻ 21 L, vận hành trong 60 ngày liên tiếp và có 3 lần lặp lại. Nguyên liệu ủ được phối trộn theo tỷ lệ 50% phân bò và 50% thân bắp, trong đó thân bắp được cắt nhỏ cỡ 10 cm. Kết quả thí nghiệm cho thấy tất cả các thông số pH, nhiệt độ, độ kiềm của mẻ ủ đều phù hợp để vận hành. Lượng khí sinh ra của các nghiệm thức xử lý ở 2 ngày, 5 ngày, 8 ngày được ghi nhận là 153,4±9,6 L, 206,4±8,4 L và 174±11,1 L; năng suất sinh khí của các nghiệm thức không khác biệt và đạt giá trị 392,7±9,8 L/kg VSphânhủy, 469,8±10,1 L/kg VSphânhủy và 497,1±13,3 L/kg VSphânhủy. Tất cả các nghiệm thức đều sản sinh lượng CH4 thấp ở giai đoạn đầu nhưng tăng dần theo thời gian ủ và đạt hiệu quả sử dụng sau 10 ngày ủ. Kết quả cho thấy có thể chọn mốc thời gian 5 ngày để xử lý thân cây bắp trước khi đưa vào hầm ủ biogas.

L’objectif de cette étude était d’évaluer et de comparer la force d’adhésion de deux résines de collage: le ClearfilTM Esthetic Cement & DC Bond Kit (C) et le RelyXTM Unicem (R), sur trois adhérents différents : une surface d’émail, un alliage de métaux non précieux (Np) et un alliage de métaux semi-précieux (Sp). La surface des échantillons des alliages métalliques a subi différents traitements de surface. Sur l’émail (n=15) ainsi que sur les plaquettes d’alliages Np et Sp (n=15), des cylindres de résine étaient appliqués et polymérisés. Suite au processus de collage, les échantillons ont été incubés à 37°C pendant 24 heures, puis ont subi 500 cycles de thermocyclage. Des tests de cisaillement ont été effectués, suivi par l’analyse de la surface des échantillons au microscope à balayage électronique. Une comparaison de type T-test et des comparaisons multiples post hoc, ont été effectuées pour l’analyse statistique (p 0,05). Sur l’émail, les résultats ont démontré que la résine C présentait une force d'adhésion moyenne statistiquement supérieure (33,97±17,18 MPa) à la résine R (10,48±11,23 MPa) (p 0,05). Le type d’alliage utilisé n’influençait pas la force d’adhésion, et ce, peu importe le type de résine de collage (p>0,05). Pour le groupe Sp, la résine C a démontré une adhésion statistiquement supérieure à la résine R, et ce, pour tous les traitements de surface (p 0,05). En conclusion, la résine C a démontré des résultats d’adhésion significativement supérieurs à la résine R sur l’émail ainsi que sur presque toutes les surfaces traitées des alliages de métaux. / The objective of this study was to assess and compare the shear bond strength of two types of resin cements: ClearfilTM Esthetic Cement & DC Bond Kit (C) and RelyXTM Unicem (R) when these resins cements were applied to three different surfaces: enamel, non precious metal alloy (Np) and semi-precious metal alloy (Sp). Both types of alloy surfaces were treated differently. On both enamel (n=15) and alloy plates Np and Sp (n=15) surfaces, cylinder shaped resin cements were bonded and lightpolymerized. After the adhesion process, all samples were placed into an incubator at 37°C for 24 hours and 500 thermal cycles were accomplished. Shear bond strength tests followed by electron microscopy analysis were performed. Statistical analysis was done using a T-test comparison followed by a post hoc multiple comparisons (p 0.05). The results on enamel showed that the C resin cement had a statistically significant higher bond strength (33.97±17.18 MPa) than the R resin cement (10.48±11.23 MPa) (p 0.05). The type of alloy did not influence the bond strength regardless the type of resin cement (p 0.05). For the Sp group, the bond strength was statistically higher for the C resin than for the R resin and those results are valuable for all treated surfaces (p 0.05). To conclude, the C resin cement showed a statistically significant higher bond strength than the R resin cement with enamel and most of the metal alloy treated.

L'objectif général de cette thèse de doctorat est de caractériser les propriétés de membranes PFSA de type Nafion N115 et Nafion NRE212 en termes de sorption d'eau, de propriétés de transport et de propriétés mécaniques, sur une large gamme de conditions expérimentales. Nous avons réalisé de très nombreuses mesures afin de comparer les résultats avec les données de la littérature, souvent dispersées. Des protocoles simples et reproductibles nous ont permis de mesurer les propriétés des membranes et d'étudier l'influence de certains paramètres sur leur variation. Les échantillons ont par exemple été séchés à différentes températures et nous avons étudié l'effet de ce prétraitement thermique sur la capacité de sorption, les propriétés de transport et les propriétés mécaniques. Les membranes Nafion ont également été exposées à une température modérée (60°C - 80°C) et à une humidité relative constante (RH = 0.3 à 0.95) pendant plusieurs semaines, conditions à l'origine d'un phénomène dit de "vieillissement hygrothermique" qui affecte leur capacité de sorption et leur conductivité protonique. De tels effets ont été observés mais ils se sont révélés réversibles et sans conséquences notables en terme de performances une fois les membranes utilisées en pile à combustible. Nos résultats peuvent être utilisés dans des études impliquant le transport et la gestion de l'eau dans les piles à combustible ainsi que leur durabilité, en particulier pour de la simulation numérique ou de la modélisation. Plus fondamentalement, ils peuvent aider à comprendre la thermodynamique de sorption et les phénomènes de transport dans les membranes PFSA / The overall aim of this PhD thesis was to characterize the properties of commercial Nafion N115 and Nafion NRE212 membranes in term of water sorption, transport, and mechanical properties over a wide range of experimental conditions. Because of the high dispersion of the data in the literature, our primary objective was to gather a comprehensive set of experimental measurements and to compare them with published results. Simple and reproducible protocols allowed us to measure the membrane properties over a wide range of experimental conditions and to study the influence of certain parameters on their evolution. For example, the samples were heat-treated at different temperatures and the effect of thermal history on water sorption, transport and mechanical properties was investigated. Nafion membranes were also exposed to moderate temperature (60°C - 80°C) and constant relative humidity (RH = 0.3 to 0.95) for long periods of time, which is known to cause a so-called ?hygrothermal aging? resulting in a decrease in their sorption capacity and proton conductivity. Such effects were observed but they appeared to be reversible and without noticeable consequences in term of fuel cell performance. Our experimental results can be used in studies involving water transport, water management and durability of fuel cells, especially for numerical simulation or modelling. More fundamentally, they can help understanding the thermodynamics of sorption and transport phenomena in PFSA membranes

The suitability of water hyacinth in biogas production was evaluated as a means of waste management in the interests of sustainable energy production. Batch anaerobic digestion (AD) of water hyacinth was conducted to determine the optimal pre-treatment method for maximum methane production. Physical pre-treatment methods produced a highest cumulative methane of 2.3 L during batch AD. The selected pre-treatment method, hand-cutting, was further evaluated in a semi-continuous AD using both mono- and co-digestion. The emphasis was on identifying microbial communities involved and their response to organic loading rates (OLRs). The Illumina Miseq results proved that bacterial communities were more sensitive to disturbances caused by irregular OLRs as compared to archaeal communities. In addition, the variation in substrate nutrients as a result of mono- and co-digestion of water hyacinth, contributed to variations in the bacterial diversity. For example, Bacteroides and Petrimonas diversity varied between mono- and co-digestion. Overall, the study verified that water hyacinth is a suitable feedstock for biogas production and the simple pre-treatment methods are recommended. Furthermore, OLRs influenced the microbial community structure and associated biogas yield. / National Research Foundation (South Africa) / Environmental Science / M. Sc. (Environmental Science)

Este trabalho investigou o efeito da temperatura nos sistemas aneróbios com células imobilizadas tendo como estudo de caso um sistema anaeróbio em duas fases. Inicialmente, foram realizados experimentos preliminares com um sistema em duas fases composto por Reator Acidogênico Horizontal Tubular (RAHT) seguido de Reator Anaeróbio Horizontal de Leito Fixo (RAHLF), nas temperaturas de 15ºC, 20ºC e 25ºC. Os resultados mostraram que o RAHT alcançou 48% de remoção de DQO e que a desvantagem da ausência de microrganismos consumidores de H2 no sistema praticamente não afetou a produção de ácido acético. Pôde-se observar que na faixa de temperatura estudada o RAHT não apresentou mudanças significativas em seu desempenho. Posteriormente foram realizados experimentos com cinco reatores metanogênicos do tipo RAHLF, alimentados com esgoto sintético simulando o efluente do RAHT, com velocidades de 10,4 cm/h, a 52,0 cm/h e temperatura de 15ºC a 35ºC. Os resultados permitiriam o desenvolvimento de um modelo empírico-estatístico para simulação do desempenho dos reatores, tendo como variáveis a velocidade superficial do líquido sobre as biopartículas e a temperatura de operação. Os resultados preditos pelo modelo demonstraram boa representatividade dos valores experimentais. Com isso, foi possível observar as influências da velocidade superficial (vs) e da temperatura, nas concentrações residuais de substrato (Sr) e nas constantes cinéticas aparentes de primeira ordem (K1app). Conclui-se então, que apesar do aumento de vs resultar em maiores valores de K1app, também foi observado aumento no valor de Sr indicando que existe um tempo de contato mínimo entre os microrganismos e o substrato. / The effects of temperature and superficial velocity in an anaerobic methanogenic immobilized cell rector of a two phase-system were investigated. Preliminarily, a Tubular Horizontal Acidogenic Reactor (THAR) followed by Horizontal-flow Anaerobic Immobilized Biomass (HAIB) composed the experimental system, operated at the temperatures of 15°C, 20°C and 25°C. COD removal efficiency of 48% was observed in the THAR. Likewise, the disadvantage of the absence of H2-consumer methanogenics microorganisms in the system almost did not affect the production of acetic acid. The temperature variation has not caused significant changes in the THAR performance. The next step was the development of experiments using five methanogenics HAIB reactors fed on synthetic wastewater simulating THAR effluent having superficial velocities from 10,4 cm/h to 52,0 cm/h and temperature from 15°C to 35°C. The results enabled the development of a statistical-empiric modeling to simulate the reactors performance using the liquid superficial velocities and the temperature operation as model variables. The model demonstrated a good agreement with the experimental values. The influence of the superficial velocities (vs) and temperature, in the substrate residual concentration (Sr) and in the first order (K1app) apparent kinetic constant was observed. Despite the K1app values have increased largely with vs, the Sr concentration also increased. These results permit to conclude that a minimum contact time between the microorganisms and the substrate may be necessary in such processes.

O projeto consistiu em avaliar o emprego de polímeros catiônicos e aniônicos de diferentes pesos moleculares como auxiliares de filtração no tratamento de águas de abastecimento proveniente de mananciais com alto grau de eutrofização com vistas a possibilitar a otimização da remoção de material particulado e minimização da evolução da perda de carga. O aparato experimental é composto, principalmente, por 4 filtros em escala piloto de alta taxa do tipo camada profunda e fluxo descendente por gravidade operados em paralelo. Os filtros possuem 5 m de altura e diâmetro interno de 150 mm. O procedimento experimental foi dividido em três etapas, execução de ensaios de fluidificação e expansão do leito dos filtros e utilização de polímeros catiônicos e de polímero aniônico como auxiliares de filtração. A primeira etapa teve como objetivo definir parâmetros de dimensionamento do sistema de lavagem em contra-corrente com ar e água e nas duas etapas seguintes foram realizados os ensaios de filtração a uma taxa de 500 m³/m²/dia, com a utilização dos polímeros com três dosagens diferentes. Os polímeros utilizados foram CA-2577, CA-2581, CD-2592 e N1986. Estes possuem estrutura e pesos moleculares variáveis, de forma que o trabalho tivesse uma maior amplitude. Os valores médios de turbidez, para a primeira etapa dos ensaios de filtração, foram de 2,36 ± 0,28 UNT e 1,12 ± 0,21 UNT para água bruta e decantada, respectivamente, 0,26 ± 0,07 UNT para o filtro F1 com antracito, 0,25 ± 0,08 UNT para o filtro F3 com antracito e adição de polímero, 0,29 ± 0,08 UNT para o filtro F2 com areia e 0,26 ± 0,08 UNT para o filtro F4 com areia e adição de polímero. Para a segunda etapa dos ensaios de filtração os valores médios de turbidez foram de 2,03 ± 0,36 UNT para água bruta, 0,80 ± 0,21 UNT para água decantada, 0,09 ± 0,03 UNT para o filtro F1, sem adição de polímero, e 0,15 ± 0,04, 0,16 ± 0,03 e 0,10 ± 0,04 UNT para os filtros F2, F3 e F4, respectivamente, todos com adição de polímero. Os resultados experimentais possibilitaram concluir que a adoção do antracito como material filtrante do tipo camada única e profunda apresenta a vantagem de permitir uma menor velocidade ascensional de água de lavagem para uma determinada expansão quando comparado a um filtro de areia de idêntica granulometria. A aplicação dos polímeros catiônicos e do polímero aniônico como auxiliares de filtração não proporcionou para nenhuma dosagem utilizada melhora significativa no comportamento dos filtros. Uma eventual melhora ou piora foi insignificante e estava ligada à qualidade da água decantada. No que diz respeito à perda de carga, os filtros com antracito tiveram carreiras de filtração mais longas quando comparados com os de areia, independente da utilização dos polímeros. / The project was to evaluate the use of anionic and cationic polymers of different molecular weights as filter aids to treat drinking water treatment of surface water sources with high degree of eutrophication, particularly with regard to particulate matter removal optimization and head loss rate minimization. The experimental apparatus was composed of four pilot scale, deep bed, down flow rapid gravity filters, operated in parallel. The filter columns were 5 m high, had inner diameter of 150 mm. The experimental procedure was divided in three stages, conduction of media fluidization and media expansion tests and cationic and anionic polymers application as filter aid. The first stage aims was to define design parameters for the filter backwashing system with water and air and in the two next phases the tests were conducted at a filtration rate of 500 m³/m²/day, with the use of polymers with three different dosages. The polymers tested were CA- 2577, CA-2581, CD-2592 and N1986. They have different structure and molecular weights, thus making wider the array of possibilities tested. The average values of turbidity, for the first stage of testing filtration, were 2.36 ± 0.28 and 1.12 ± 0.21 NTU for raw and settled water, respectively, 0.26 ± 0.07 NTU to the filter F1 with anthracite, 0.25 ± 0.08 NTU for the filter F3 with anthracite and addition of polymer, 0.29 ± 0.08 NTU for the filter F2 with sand and 0.26 ± 0.08 NTU for the filter F4 with sand and the addition of polymer. For the second stage of testing of the filter values of turbidity were 2.03 ± 0.36 NTU for raw water, 0.80 ± 0.21 NTU for settled water, 0.09 ± 0.03 for the filter F1, without the addition of polymer, and 0.15 ± 0.04, 0.16 ± 0.03 and 0.10 ± 0.04 NTU for filters F2, F3 and F4, respectively, all with the addition of polymer. The experimental results led us to conclusion that the adoption of anthracite as single media in deep bed filtration presents the advantage of a lower ascent backwash water velocity for any given bed expansion as compared to deep bed filtration through sand with the same granulometric characteristic. Application of cationic and anionic polymers as filter aids did not lead to any significant improvement in the behavior of pilot scale filters, regardless of applied polymer dosage. Any eventual improvement or worsening was not significant and was closely related to the settled water quality. Regarding the head loss, the filters with anthracite had longer filtration careers when compared to sand, regardless the use of polymers.

Ces travaux de thèse constituent une contribution au développement de composites chanvre/époxy 100% bio-sourcés. Les enjeux environnementaux actuels favorisent l'émergence de matériaux issus de ressources renouvelables telles que les fibres végétales mais conduisant aussi à une large gamme de synthons bio-sourcés, notamment à l'origine de prépolymères époxydiques. Une étude approfondie des deux constituants (fibres de chanvre et matrices polyépoxydiques) est réalisée avant l'étape d'élaboration des composites. Un traitement au CO2 supercritique est appliqué sur les fibres de chanvre utilisées comme renfort dans les matériaux composites. Le résultat de ce traitement mène à une meilleure individualisation ainsi qu'à une baisse du pouvoir hygroscopique des fibres. Ces aspects, décisifs pour garantir de bonnes propriétés pour le composite final, sont néanmoins nuancés par une baisse des propriétés ultimes en traction à l'échelle des fibres mais également à l'échelle du composite. De la même façon, la diminution du pouvoir hygroscopique des fibres après traitement se répercute à l'échelle du composite, permettant ainsi d'améliorer la durabilité du composite. La synthèse des résines époxydiques utilisées dans cette étude est réalisée à partir de ressources renouvelables et abondantes telles que la lignine. Les polyépoxydes thermodurcissables ainsi préparés présentent de bonnes performances, compatibles avec le cahier des charges pour des applications composites à renfort végétal. Au regard des résultats obtenus, les composites 100% bio-sourcés sont des matériaux d'avenir. Leur développement nécessite néanmoins une étude approfondie de leur durabilité. / This thesis contributes to the development of 100% bio-based hemp/epoxy composites. Current environmental issues favor the emergence of materials derived from renewable resources such as plant fibres and a wide range of bio-based building-blocks, source of epoxy prepolymers in particular. An intensive investigation of the two constituents (hemp fibres and polyepoxidic matrix) is carried out before the composites manufacturing. Supercritical CO2 treatment is applied to hemp fibres used as reinforcement in composite materials. This treatment, not optimized, leads to better individualization as well as a decrease in the hygroscopic power of the fibres. These aspects, which are essential in order to guarantee good properties for the final composite, are nevertheless qualified by a loss of mechanical properties at the fibre scale but also at the composite scale. In the same way, the decrease in the hygroscopic power of the hemp fibres after treatment is reflected at the composite scale, thus improving the durability of the crosslinked material. The synthesis of the epoxy resins used in this study is made from abundant resources such as lignin. The thermosetting polyepoxides prepared in this study have good performance, compatible with the specification for composite applications with plant fibres reinforcement. In view of the results obtained, 100% bio-based composites are materials with a high future potential. Nevertheless, their development requires a comprehensive sustainability study.