Le microbiote intestinal est constitué d’un écosystème complexe de microorganismes appartenant à différents règnes. Cependant, la majorité de ces microorganismes sont d’origine bactérienne. Par conséquent, de nombreuses études, y compris la présente, se concentrent sur l’étude des communautés bactériennes. Les microorganismes ont développé une relation mutualiste avec le corps humain et agissent de plusieurs manières sur sa santé. Une perturbation du microbiote intestinal, nommée dysbiose, est reliée au développement d’une multitude de problèmes de santé chez diverses espèces animales. La transplantation de microbiote fécal suscite l’intérêt dans le domaine de la médecine vétérinaire. La préparation et l’entreposage affectent la composition et la viabilité bactérienne des fèces destinées à la transplantation de microbiote fécal (TMF). Jusqu’à présent, il demeure l’absence d’un protocole vétérinaire pour effectuer la préparation et l’entreposage des transplants fécaux canins. Par conséquent, l’objectif de cette étude était de comparer la viabilité bactérienne d’échantillons fécaux en présence et en absence d’oxygène et d’effectuer la congélation à l’aide de deux cryoprotecteurs différents. Les hypothèses de ce projet étaient les suivantes : la préparation des échantillons en absence d’oxygène préservera la viabilité bactérienne, l’utilisation d’un cryoprotecteur contenant des antioxydants pour la congélation générera le meilleur taux de viabilité, et le microbiote de chaque individu n’aura pas la même capacité à résister aux effets de la préparation et de l’entreposage. Les fèces de 10 chiens en santé ont été collectées et immédiatement transférées à l’intérieur d’une chambre anaérobique. Des aliquotes de 1,8 g ont été diluées dans 7,2 ml d’un cryoprotecteur contenant du glycérol à 10% (Gly) ou des antioxydants (Cryo). Les échantillons ont été homogénéisés et filtrés en condition aérobique (Ae) et en condition anaérobique (An) à l’intérieur d’une chambre anaérobique, simulant la préparation de la TMF. Les échantillons ont été congelés à -20 °C durant 90 jours (F) pour l’évaluation des effets de l’entreposage. La viabilité bactérienne des échantillons a été déterminée à l’aide de la cytométrie de flux. L’analyse de la composition bactérienne chez les 10 donneurs de matières fécales a été réalisée par le séquençage de la région V4 du gène de l’ARNr 16S à l’aide de la plateforme Illumina MiSeq. Les échantillons non congelés, préparés en absence d’oxygène et dilués avec Cryo présentaient les plus grands taux de viabilité (66,78 %) par rapport aux autres groupes (p < 0,05). Les échantillons exposés à l’oxygène avaient une viabilité bactérienne inférieure (p < 0,01). Toutefois, les échantillons dilués avec Cryo présentaient une viabilité plus élevée (65,26 %) que les échantillons dilués dans Gly (55,20 % ; p < 0,001) en présence d’oxygène. La viabilité bactérienne a diminué en raison de la congélation des échantillons (p < 0,001). L’ensemble des échantillons frais avaient une viabilité médiane de 62,23 % et, à la suite de la congélation, elle était de 22,68 %. Cependant, les échantillons congelés à l’aide de glycérol avaient une viabilité plus élevée (30,61 % ; p < 0,001). Le genre Prevotella était fortement corrélé à la viabilité (R = 0,731 ; p < 0,05, R = 0,756 ; p < 0,05, R = 0,834 ; p < 0,01, R = 0,752 ; p < 0,05). Ces résultats indiquent que la viabilité bactérienne est optimale lors de l’utilisation de matières fécales en absence d’oxygène et lors d’une dilution à l’aide d’un cryoprotecteur contenant des antioxydants. La congélation a significativement réduit la viabilité bactérienne, mais le glycérol semble mieux préserver les bactéries. La présence de certaines espèces plus résistantes et l’impact de la composition du microbiote sur l’efficacité de la TMF nécessitent une enquête plus approfondie. / The intestinal microbiota is made up of a complex ecosystem of microorganisms belonging to different kingdoms. However, bacterial cells are much more numerous. Therefore, many studies, including the present one, focus on the study of bacterial communities. Microorganisms have developed a mutualistic relationship with the animal body and act in several ways on its health. A disturbance of the intestinal microbiota, called dysbiosis, is linked to the development of a multitude of health problems in various animal species. There is an emerging interest in the transplantation of fecal microbiota in veterinary medicine. Preparation and storage affect the quality of transplants intended for faecal microbiota transplantation (FMT). Considering the absence of a protocol in veterinary medicine, the objective of this study was to optimize bacterial viability during the preparation and storage of canine fecal transplants. The hypotheses of this project were that the preparation of samples in the absence of oxygen will preserve bacterial viability, that the use of a cryoprotectant containing antioxidants for freezing will yield the best viability rate and the microbiota of individuals does not have the same ability to withstand the effects of preparation and storage. Feces from ten healthy dogs were collected, and immediately transferred inside an anaerobic chamber. Aliquots of 1.8 g were diluted in 7.2 ml of a cryoprotectant containing glycerol (Gly) or antioxidants (Cryo). The samples were homogenized and filtered, simulating the TMF preparation. To evaluate the impact of oxygen on bacterial viability, the procedures were performed outside (Ae) and inside (An) the anaerobic chamber. Samples were frozen at -20°C for 90 days (F) to evaluate effect of freezing. The bacterial viability of samples was determined using flow cytometry. Analysis of the bacterial composition was performed by sequencing the V4 region of the 16S rRNA gene, using the Illumina MiSeq platform. Fresh samples prepared under anaerobiosis and diluted with Cryo had the highest viability (66.78%) compared to the other groups (p < 0.05). Bacterial viability was affected by oxygen (p < 0.01) but solutions prepared with Cryo had higher viability (65.26%) than samples diluted in Gly (55.20%; p < 0.001). Freezing decreased bacterial viability from 62.23% to 22.68% (p < 0.001). However, samples frozen using glycerol showed higher viability (30.61%; p < 0.001). The genus Prevotella was strongly correlated with viability (R = 0.731; p < 0.05, R = 0.756; p < 0.05, R = 0.834; p < 0.01, R = 0.752; p < 0.05). These results show that bacterial viability is optimal when preparing feces under anaerobic conditions and using a cryoprotectant containing antioxidants. If freezing is necessary, glycerol seems to preserve the bacteria better. The presence of some more resilient species and the impact of microbiota composition on the efficacy of TMF requires further investigation.

Der Nordamerikanische Waschbär (Procyon lotor Linné, 1758) gehört zu den neozonalen Vertretern der heimischen Raubsäugerfauna. Seit den 1990er Jahren tritt der in Deutschland mittlerweile fest etablierte Kleinbär verstärkt in Erscheinung und ist damit Auslöser kontroverser Diskussionen über negative Auswirkungen auf einheimische Tierarten sowie über seine Rolle als potentieller Krankheitsüberträger. Ausgehend von der Hypothese, dass der Waschbär durch Prädation lokale Bestände naturschutzfachlich relevanter Tierarten beeinträchtigen kann, wurden Waschbär-Kotproben aus einem naturnahen Tieflandbuchenwald im Müritz-Nationalpark (Mecklenburg-Vorpommern) nahrungsökologisch und im Hinblick auf den Endoparasitenbefall analysiert. Das Untersuchungsgebiet repräsentiert ein charakteristisches Binnenentwässerungsgebiet der nordostdeutschen Tiefebene, das hinsichtlich der Ressourcenausstattung ein überaus geeignetes Habitat für Waschbären darstellt. Gleichzeitig wurde anhand eines Referenzgebietes im Naturpark Feldberger Seenlandschaft (Mecklenburg-Vorpommern) geprüft, ob der Waschbär in einem anthropogen beeinflussten Lebensraum aufgrund schlechterer Ressourcenausstattung einen größeren Prädationseinfluss haben kann. Die vorliegende Dissertation ist Teil eines mehrjährigen, integrierten Forschungsprojektes (Projekt Waschbär), welches zwischen 2006 und 2011 im Teilgebiet Serrahn des Müritz-Nationalparks durchgeführt wurde. / The North American raccoon (Procyon lotor L., 1758) is an introduced carnivore species in Germany. Against the background of a vast in­crease of raccoon numbers in Germany over the last years, a contro­versial dis­cussion has developed regarding the influence of the new inha­bi­­tant on indi­genous resp. pro­tec­ted species and the potential trans­mission of diseases and parasites. Based on the hypothesis that raccoons may affect local stock of ecological relevant species through predation raccoon faecal samples were collected in a close to nature beech forest in the Müritz National Park (Mecklenburg-Western ­­Pome­ra­nia, Germany) and analysed with regard to nutrition ecology and endoparasite infes­ta­tion. The study area represents a characteris­tic inland drainage area of North-Eastern German lowlands, which provides a very suitable habitat for raccoons with regards to essential resour­ces. Simulta­neously, examinations were carried out in raccoons from a control area in the Nature Park Feldberger Seen­land­schaft (Mecklenburg-Western ­­Pome­ra­nia), focusing on the question as to whether raccoons might have higher ecological impact in an anthropogenically modified habitat due to poorer food resources. This thesis is part of a long-term and integrated research project (Projekt Waschbär), which was con­­­ducted between 2006 and 2011 in the subterritory Serrahn of the Müritz National Park.

Thesis (PhD)--University of Stellenbosch, 2010. / The aim of the study was to assess the importance of spatial and temporal variation in diet quality and abundance for determining sustainable stocking rates on commercial, communal and game ranches in a semi-arid savanna, with the ultimate goal of avoiding land degradation in the long term, to provide sustainable livelihoods in rangelands and to make policy that will help in managing the available natural resources in the rangelands. Thus, firstly the effects of grazing, fire, nitrogen and water availability on nutritional quality of grass in semi-arid savanna was assessed. Secondly, spatial and temporal variation in plant quantity and quality among management (commercial, communal and game) types and habitat types (open savanna, rocky, shrubby and pans) and stocking rates in different management types were determined. Thirdly, the quality and quantity of variation inside and outside herbivore exclosures among commercial, communal and game management and habitat types in the semi arid savanna were estimated. Fourthly, faecal profiling was used to assess the effects of different management types on diet quality in semi-arid savanna. Lastly, policy based on the results of the present study was formulated.

The thesis provides a comprehensive overview of key issues affecting practice, policy and patients, in current efforts for colorectal cancer (CRC) disease control. The global burden of CRC is expected to increase by 60% to more than 2.2 million new cases and 1.1 million deaths by 2030. CRC incidence and mortality rates vary up to 10-fold worldwide, which is thought to reflect variation in lifestyles, especially diet. Better primary prevention, and more effective early detection, in screening and surveillance, are needed to reduce the number of patients with CRC in future1. The risk factors for CRC development include genetic, behavioural, environmental and socio-economic factors. Changes to surveillance, which offer non-invasive testing and provide primary prevention interventions represent promising opportunities to improve outcomes and personalise care in those at risk of CRC. By systematic review of the literature, I highlight the gaps in comparative effectiveness analyses of post-polypectomy surveillance. Using micro-simulation methods I assess the role of non-invasive, faecal immunochemical testing in surveillance programmes, to optimise post-polypectomy surveillance programmes, and in an accompanying sub-study, I explore the value of adding an adjunct diet and lifestyle intervention. The acceptability of such revisions is exposed to patient preference evaluation by discrete choice experiment methods. These preferences are accompanied by evidence generated from the prospective evaluation of the health literacy, numeracy, sedentary behaviour levels, body mass index (BMI) and information provision about cancer risk factors, to highlight the potential opportunities for personalisation and optimisation of surveillance. Additional analysis examines the optimisation of a screening programme facing colonoscopy constraints, highlighting the attendant potential to reduce costs and save lives within current capacity.

The fate of the carbon and nitrogen in dairy farm effluent (DFE) applied onto soil was investigated through laboratory experiments and field lysimeter studies. They resulted in the development and testing of a complex carbon (C) and nitrogen (N) simulation model (CaNS-Eff) of the soil-plant-microbial system. To minimise the risk of contamination of surface waters, regulatory authorities in New Zealand promote irrigation onto land as the preferred treatment method for DFE. The allowable annual loading rates for DFE, as defined in statutory regional plans are based on annual N balance calculations, comparing N inputs to outputs from the farming system. Little information is available, however, to assess the effects that these loading rates have on the receiving environment. It is this need, to understand the fate of land-applied DFE and develop a tool to describe the process, that is addressed in this research. The microbially mediated net N mineralisation from DFE takes a central role in the turnover of DFE, as the total N in DFE is dominated by organic N. In a laboratory experiment, where DFE was applied at the standard farm loading rate of 68 kg N ha⁻¹, the net C mineralisation from the DFE was finished 13 days after application and represented 30% of the applied C, with no net N mineralisation being measured by Day 113. The soluble fraction of DFE appeared to have a microbial availability similar to that of glucose. The low and gradually changing respiration rate measured from DFE indicated a semi-continuous substrate supply to the microbial biomass, reflecting the complex nature and broad range of C compounds in DFE. The repeated application of DFE will gradually enhance the mineralisable fraction of the total soil organic N and in the long term increase net N mineralisation. To address the lack of data on the fate of faecal-N in DFE, a ¹⁵N-labelled faecal component of DFE was applied under two different water treatments onto intact soil cores with pasture growing on them. At the end of 255 days, approximately 2% of the applied faecal ¹⁵N had been leached, 11 % was in plant material, 11 % was still as effluent on the surface, and 40% remained in the soil (39% as organic N). Unmeasured gaseous losses and physical losses from the soil surface of the cores supposedly account for the remaining ¹⁵N (approximately 36%). Separate analysis of the total and ammonium nitrogen contents and ¹⁵N enrichments of the DFE and filtered sub-samples (0.5 mm, 0.2µm) showed that the faecal-N fraction was not labelled homogeneously. Due to this heterogeneity, which was exacerbated by the filtration of DFE on the soil surface, it was difficult to calculate the turnover of the total faecal-N fraction based on ¹⁵N results. By making a simplifying assumption about the enrichment of the ¹⁵N in the DFE that infiltrated the soil, the contribution from DFE-N to all plant available N fractions including soil inorganic N was estimated to have been approximately 11 % of the applied DFE-N. An initial two-year study investigating the feasibility of manipulating soil water conditions through controlled drainage to enhance denitrification from irrigated DFE was extended a further two years for this thesis project. The resulting four-year data set provided the opportunity to evaluate the sustainability of DFE application onto land, an extended data set against which to test the adequacy of CaNS-Eff, and to identify the key processes in the fate of DFE irrigated onto soil under field conditions. In the final year of DFE irrigation, 1554 kg N ha⁻¹ of DFE-N was applied onto the lysimeters, with the main removal mechanism being pasture uptake (700 kg N ha⁻¹ yr⁻¹ removed). An average of 193 kg N ha⁻¹ yr⁻¹ was leached, with 80% of this being organic N. The nitrate leaching decreased with increasing soil moisture conditions through controlled drainage. At the high DFE loading rate used, the total soil C and N, pH and the microbial biomass increased at different rates over the four years. The long-term sustainability of the application of DFE can only be maintained when the supply of inorganic N is matched by the demand of the pasture. The complex simulation model (CaNS-Eff) of the soil-plant-microbial system was developed to describe the transport and transformations of C and N components in effluents applied onto the soil. The model addresses the shortcomings in existing models and simulates the transport, adsorption and filtration of both dissolved and particulate components of an effluent. The soil matrix is divided into mobile and immobile flow domains with convective flow of solutes occurring in the mobile fraction only. Diffusion is considered to occur between the micropore and mesopore domains both between and within a soil layer, allowing dissolved material to move into the immobile zone. To select an appropriate sub-model to simulate the water fluxes within CaNS-Eff, the measured drainage volumes and water table heights from the lysimeters were compared to simulated values over four years. Two different modelling approaches were compared, a simpler water balance model, DRAINMOD, and a solution to Richards' equation, SWIM. Both models provided excellent estimation of the total amount of drainage and water table height. The greatest errors in drainage volume were associated with rain events over the summer and autumn, when antecedent soil conditions were driest. When soil water and interlayer fluxes are required at small time steps such as during infiltration under DFE-irrigation, SWIM's more mechanistic approach offered more flexibility and consequently was the sub-model selected to use within CaNS-Eff. Measured bromide leaching from the lysimeters showed that on average 18% of the bromide from an irrigation event bypassed the soil matrix and was leached in the initial drainage event. This bypass mechanism accounted for the high amount of organic N leached under DFE-irrigation onto these soils and a description of this bypass process needed to be included in CaNS-Eff. Between 80 and 90% of the N and C leached from the lysimeters was particulate (> 0.2 µm in size), demonstrating the need to describe transport of particulate material in CaNS-Eff. The filtration behaviour of four soil horizons was measured by characterising the size of C material in a DFE, applying this DFE onto intact soil cores, and collecting and analyzing the resulting leachate using the same size characterisation. After two water flushes, an average of 34% of the applied DFE-C was leached through the top 0-50 mm soil cores, with a corresponding amount of 27% being leached from the 50-150 mm soil cores. Most of the C leaching occurred during the initial DFE application onto the soil. To simulate the transport and leaching of particulate C, a sub-model was developed and parameterised that describes the movement of the effluent in terms of filtering and trapping the C within a soil horizon and then washing it out with subsequent flow events. The microbial availability of the various organic fractions within the soil system are described in CaNS-Eff by availability spectra of multiple first-order decay functions. The simulation of microbial dynamics is based on actual consumption of available C for three microbial biomass populations: heterotrophs, nitrifiers and denitrifiers. The respiration level of a population is controlled by the amount of C that is available to that population. This respiration rate can vary between low level maintenance requirements, when very little substrate is available, and higher levels when excess substrate is available to an actively growing population. The plant component is described as both above and below-ground fractions of a rye grass-clover pasture. The parameter set used in CaNS-Eff to simulate the fate of DFE irrigated onto the conventionally drained lysimeter treatments over three years with a subsequent 10 months non-irrigation period was derived from own laboratory studies, field measurements, experimental literature data and published model studies. As no systematic calibration exercise was undertaken to optimise these parameters, the parameter set should be considered as "initial best estimates" and not as a calibrated data set on which a full validation of CaNS-Eff could be based. Over the 42 months of simulation, the cumulative drainage from CaNS-Eff for the conventionally drained DFE lysimeter was always within the 95% CI of the measured value. On the basis of individual drainage bulking periods, CaNS-Eff was able to explain 92% of the variation in the measured drainage volumes. On an event basis the accuracy of the simulated water filled pore space (WFPS) was better than that of the drainage volume, with an average of 70% of the simulated WFPS values being within the 95% CI for the soil layers investigated, compared to 44% for the drainage volumes. Overall the hydrological component of CaNS-Eff, which is based on the SWIM model, could be considered as satisfactory for the purposes of predicting the soil water status and drainage volume from the conventionally drained lysimeter treatment for this study. The simulated cumulative nitrate leaching of 4.7 g NO₃-N m⁻² over the 42 months of lysimeter operation was in good agreement to the measured amount of 3.0 (± 2.7) g NO₃-N m⁻². Similarly, the total simulated ammonium leaching of 2.7g NH₄- N m⁻² was very close to the measured amount of 2.5 (± 1.35) g NH₄- N m⁻² , however the dynamics were not as close to the measured values as with the nitrate leaching. The simulated amount of organic N leached was approximately double that measured, and most of the difference originated from the simulated de-adsorption of the dissolved fraction of organic N during the l0-month period after the final DFE irrigation. The 305 g C m⁻² of simulated particulate C leached was close to the measured amount of 224 g C m⁻² over the 31 months of simulation. The dissolved C fraction was substantially over-predicted. There was good agreement in the non-adsorbed and particulate fractions of the leached C and N in DFE. However, the isothermic behaviour of the adsorbed pools indicated that a non-reversible component needed to be introduced or that the dynamics of the de-adsorption needed to be improved. Taking into account that the parameters were not calibrated but only "initial best estimates", the agreement in the dynamics and the absolute amounts between the measured and simulated values of leached C and N demonstrated that CaNS-Eff contains an adequate description of the leaching processes following DFE irrigation onto the soil. The simulated pasture N production was in reasonable agreement with the measured data. The simulated dynamics and amounts of microbial biomass in the topsoil layers were in good agreement with the measured data. This is an important result as the soil microbial biomass is the key transformation station for organic materials. Excepting the topsoil layer, the simulated total C and N dynamics were close to the measured values. The model predicted an accumulation of C and N in the topsoil layer as expected, but not measured. Although no measurements were available to compare the dynamics and amounts of the soil NO₃-N and NH₄-N, the simulated values appear realistic for an effluent treatment site and are consistent with measured pasture data. Considering the large amount of total N and C applied onto the lysimeters over the 42 months of operation (4 t ha⁻¹ of N and 42 t ha⁻¹0f C), the various forms of C and N in dissolved and particulate DFE as well as in returned pasture, and that the parameters used in the test have not been calibrated, the simulated values from CaNS-Eff compared satisfactorily to the measured data.

Ghana as a rapidly growing and urbanizing middle-income country is facing a number of challenges, including (1) implementing a sanitary, environmental-friendly, and economically-sound waste management system; (2) increasing its agricultural productivity in a sustainable way to meet the growing domestic food demand; and (3) providing livelihood opportunities in both rural and urban areas. Using the black soldier fly (BSF), a particularly beneficial insect, to locally and cost-effectively valorise abundant, high-impacting, and nutrient rich organic waste streams, such as food waste (FW) and faecal sludge (FS), into affordable and sustainable farming inputs like organic fertilizer and animal feed products, could tackle all these challenges at the same time. Therefore, this study aimed at (1) providing a comprehensive overview of BSF technology; (2) investigating the technical feasibility of valorising food waste and faecal sludge using a low-tech BSF bioconversion system; and (3) assessing the economic viability of such system in the Ghanaian context. First, through an extensive literature review and field visits of BSF units, the different dimensions of the BSF technology were discussed, BSF waste treatment method was compared to other options for organic waste valorisation, case studies of implementation were documented, the status of the research was highlighted, and research gaps were identified. In a second step, a 10-week field work consisting of establishing a BSF colony and recording rearing performance in the one hand, and running two waste treatment trials using a low-tech BSF system on the other hand, enabled demonstrating the technical feasibility of co-digesting FW and FS with the BSF, as well as artificially rearing the BSF in Ghana using a low-tech system. However, further research is needed to characterize the bioconversion products, determine the optimal FW/FS ratio, and optimize the rearing performance of the system. Finally, a costbenefit analysis was conducted to compare three scenarios: (1) co-composting FW and FS into fertilizer; (2) co-digesting FW and FS with BSF into only animal feed; and (3) co-digesting FW and FS with BSF into both animal feed and fertilizer. By building financial models for each scenario and performing a sensitivity analysis, it was established that, in the Ghanaian context, scenario (3) was the most likely to be viable, as well as the most profitable, followed by scenario (1).  On the other hand, scenario (2) was associated with a much lower likelihood to be viable. Eventually, the choice of the optimal valorisation option for FW and FS should consider the local context and priorities. / Ghana, ett snabbväxande medelinkomstland med kraftig urbanisering, står inför ett antal utmaningar, bland annat att (1) införa ett sanitärt, miljövänligt och ekonomiskt avfallshanteringssystem; (2) öka sin jordbruksproduktivitet för att möta den växande inhemska efterfrågan på livsmedel på ett hållbart sätt, och (3) erbjuda möjligheter till försörjning både på landsbygden och i städerna. Genom att använda den svarta soldatflugan (SSF), en särskilt fördelaktig insekt, för att lokalt omvandla rikligt förekommande och näringsrika organiska avfallsströmmar, såsom matavfall (MA) och fekalslam (FS) till prisvärda och hållbara jordbruksinsatsvaror, såsom organiskt gödselmedel och djurfoder, skulle man på ett kostnadseffektivt sätt kunna ta itu med alla dessa utmaningar samtidigt. Därför syftade denna studie till (1) att ge en övergripande översikt över SSF-teknik; (2) undersöka den tekniska möjligheten att skapa värdefulla produkter av matavfall och fekalslam med hjälp av ett biotekniskt system med lågteknologisk SSF i Ghana; och (3) bedöma det ekonomiska systemets bärkraft. Först, baserat på en omfattande litteraturstudie och fältbesök, diskuterades SSF-teknikens olika dimensioner, jämfördes SSF-avfallshanteringsmetoden med andra alternativ för organiska avfallsvalorisationer, dokumenterades fallstudier, redovisades forskningsläget och identifierades kunskapsluckor. I ett andra steg genomfördes ett 10 veckors fältarbete som bestod dels av att etablera en SSF-koloni och dokumentera uppfödningsprestanda, dels att göra två avfallsbehandlingsförsök med hjälp av ett SSF-system med lågteknologi. Därigenom visades att det är tekniskt möjligt att sambehandla MA och FS med SSF, liksom att föda upp SSF i Ghana med hjälp av ett lågteknologiskt system. Det behövs dock ytterligare forskning för att karakterisera slutprodukterna, bestämma det optimala MA/FS-förhållandet och optimera systemets uppfödningsprestanda. Slutligen genomfördes en kostnadsnyttoanalys för att jämföra tre scenarier: (1) kompostering av MA och FS till gödselmedel; (2) sambehandling av MA och FS med SSF till endast djurfoder; och (3) sambehandling av MA och FS med SSF till både djurfoder och gödningsmedel. Genom att bygga modeller för varje scenario och genomföra en känslighetsanalys fastställdes att för Ghana var scenario (3) mest sannolikt livskraftigt, liksom det mest lönsamma, följt av scenario (1). Scenario (2) förknippat med en mycket lägre sannolikhet att vara genomförbart. Till sist bör valet av det optimala behandlingsalternativet för MA och FS ta hänsyn till lokala förhållanden. / Le Ghana, pays en voie de développement connaissant une forte croissance et urbanisation, est confronté à un certain nombre de défis, parmi lesquels (1) la mise en place d’un système de gestion des déchets performant du point de vue sanitaire, environnemental, et économique ; (2) l’augmentation durable de sa productivité agricole afin de répondre à la demande alimentaire croissante dans le pays ; et (3) la création d’opportunités économiques pour ses populations rurales et urbaines. Utiliser la mouche soldat noire (MSN), un insecte particulièrement bénéfique, pour valoriser localement et à moindre coût des déchets organiques abondants, riches en nutriments, et responsables d’importants dommages sanitaires et environnementaux, tels que les déchets alimentaires (DA) et boues de vidange (BV), en intrants agricoles écologiques et bon marché, comme des produits alimentaires pour animaux ou de l’engrais organique, contribuerait à relever tous ces défis à la fois. Ainsi, cette étude visait à (1) réaliser un état de l’art de la technologie liée à la MSN ; (2) étudier la faisabilité technique de valoriser les DA et BV à l’aide d’un system à faible technologie reposant sur la MSN ; (2) analyser la viabilité économique d’un tel system dans le contexte Ghanéen.  Dans un premier temps, un examen approfondi de la littérature scientifique et des visites d’unités de recyclage utilisant la MSN ont permis d’analyser les différentes dimensions de cette technologie, de la comparer à d’autres options de valorisation pour les déchets organiques, de présenter des études de cas, de donner un aperçu de l’état actuel de la recherche, ainsi que de d’identifier les principales lacunes et besoins en matière de recherche. Dans un second temps, dans le cadre d’une étude de terrain réalisée sur une période de dix semaines, un système d’élevage en captivité de MSN a été mis en place et son efficacité analysée, tandis qu’en parallèle deux séries d’expériences de traitement des déchets ont été réalisées. Ces différentes activités ont permis de démontrer que le co-traitement des DA et BA, ainsi que l’élevage en captivité de la MSN à l’aide d’un system low-tech est techniquement réalisable dans le contexte Ghanéen. Toutefois, des recherches supplémentaires sont nécessaires afin d’analyses les propriétés des produits de valorisation, d’établir le ratio DA/BV optimal, et d’optimiser les performances d’élevage. Enfin, une analyse coûts-bénéfices a été réalisée afin de comparer trois scenarios : (1) co-compostage des DA et BV afin de produire de l’engrais ; (2) co-traitement des DA et BV à l’aide de la MSN débouchant sur la production d’aliments pour animaux ; et (3) co-traitement des DA et BV à l’aide de la MSN pour produire à la fois des aliments pour animaux et de l’engrais. La construction de modèles financiers et la réalisation d’une analyse de sensibilité ont permis de démontrer que dans le contexte Ghanéen, le scenario (3) présentait la plus grande probabilité d’être viable et était le plus rentable, suivi par le scenario (1). En revanche, la probabilité que le scenario (2) soit viable s’est révélée beaucoup plus faible. Ultimement, la sélection de la meilleure méthode de valorisation devrait tenir compte du contexte et des priorités locaux.