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Item Essai d’amélioration de la teneur en phosphore des composts produits par co-compostage des pailles de riz et d’adjuvants organiques avec les phosphates naturels de Matongo(UB, FS, 2025-01) Igiraneza, Fulgence; Sous la direction de : Dr. Rucakumugufi Daniel (Directeur); Prof. Kaboneka Salvator (Co-Directeur)The improvement of phosphorus availability in agricultural soils is a major challenge for soil fertility and the optimization of crop yields. However, the use of Matongo natural’s phosphates is limited due to their low solubility. This thesis presents a study on enhancing the phosphorus content of composts obtained through the co-composting of tithonia diversifolia and rice straw with various organic additives, including pig manure, poultry droppings, and cow dung, in combination with Matongo phosphates. The main objective of this research is to optimize the valorization of agricultural waste while increasing soil fertility through phosphorus-enriched composts. Initially, an analysis of the physicochemical characteristics of raw materials was conducted to determine their composting potential. Then, several compost formulations were developed, varying the types of input combinations. The resulting composts were subjected to maturation tests and phosphorus content analysis. The results recorded for the control compost samples: E450, E591, and E603 were respectively: 1.05±0.120% P₂O₅; 0.88±0.042% P₂O₅; and 0.69±0.245% P₂O₅. Meanwhile, the composts enriched with Matongo phosphates (E101, E205, E308, E708, and E805) showed the following phosphorus content: 3.56±0.035% P₂O₅, 2.99±0.071% P₂O₅, 3.42±0.081% P₂O₅, 3.12±0.056% P₂O₅, and 3.14±0.070% P₂O₅, respectively. The results indicate that adding Matongo phosphates, in combination with organic additives, significantly increases the phosphorus content of the composts. Physicochemical parameter analyses, heavy metal assessments, and phytotoxicity tests were conducted on the produced composts to evaluate their stability and maturity. Except for lead (Pb) content, which exceeds the quality standards for compost intended for fertilization, all other tested parameters comply with the established quality standards for high-quality compost. Among the tested additives, the cow dung adjuvant proved to be a better phosphate solubilizer than the two others adjuvants tested. This study contributes to the valorization of agricultural residues and the sustainable management of resources while addressing the growing need for phosphorus-rich organic fertilizers in agriculture. The findings of this research open up promising perspectives for the development of innovative and sustainable composting practices.Item Analyse intégrée de la chaine de valeur de la filière riz de la plaine de l’Imbo(UB, FSEA, 2025-12) Nizigiyimana, Alexis; Sous la direction du : Directeur : Dr. Dismas MANIRAKIZA; Co-Directeur : Dr. Ir. Patrice NDIMANYARice is the primary cereal for human consumption, serving as the staple food for nearly 50% of the global population. In Africa, the demand for rice has significantly increased, largely due to urbanization, leading to a greater reliance on imports. In Burundi, although irrigated rice cultivation was introduced in the Imbo plain to enhance food security, national production remains insufficient to meet this growing demand, resulting in substantial imports. The rice sector in Burundi is crucial for household incomes, yet it faces several challenges, such as high input costs and limited access to resources. In this context, the study aims to analyze the value chain of the rice sector by assessing the average net income generated by each actor and examining his or her interactions. To achieve these objectives, a survey was conducted with 96 actors selected using the "snowball" method, including 41 rice farmers, 20 millers, 15 wholesalers, 10 retailers, and 10 consumers. Data collection was carried out using the KoBoCollect application, followed by data cleaning and coding. The results were analyzed using EXCEL and SPSS software, allowing the research questions to be addressed. The findings indicate that the average net income generated by the actors varies significantly according to their specific roles. Producers report an average net income of 5,628,973 F per season, while millers generate 838,785 F. Wholesalers, on the other hand, show an average net income of 7,880,534 F, surpassing that of retailers, who earn 3,878,370 F. Furthermore, multiple linear regression analysis reveals that fluctuations in rice prices are significantly influenced by production costs and climatic conditions. Other variables, such as consumer demand and government policies, did not exhibit significant effects. Finally, the study highlights several challenges faced by the actors in the chain, including high input costs and limited access to these resources. Concerns related to the quality of raw rice and equipment costs are also identified. Commercialization is hindered by transportation difficulties and price fluctuations, while price volatility and income constraints represent significant obstacles for consumers.Item Analyse de la qualité de l’eau des étangs piscicoles de la plaine de l’Imbo : Cas de Bujumbura(UB, IPA, 2026-01) Nkurunziza, Hermès; Sous la direction de : Dr Nkurunziza Rémy MariePond aquaculture in Burundi is expanding through government initiatives and national and international projects aimed at enhancing food security and rural development. To support the planning of sustainable management strategies for fish ponds in the Imbo Plain, a water quality study was conducted on two ponds located at RUKARAMU (site 1) and MINEAGRIE (site 2). Samples were collected in July 2025 at a depth of 30–40 cm and analyzed at the laboratory of the ISABU. Thirteen physico-chemical parameters were investigated: temperature, pH, electrical conductivity, TDS, DO, nutrients (nitrates, phosphates), major ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl⁻, SO₄²⁻, F⁻), alkalinity, Kjeldahl nitrogen, minor elements (Fe, Mn), total hardness, and heavy metals (Pb, Cd) and transparency. The results indicate that most parameters comply with recommended standards for tropical aquaculture. Nitrate concentrations are within acceptable limits (0.1–1 mg/l), whereas phosphate levels are slightly elevated (0.05–0.07 mg/l), suggesting a potential risk of eutrophication. Dissolved oxygen is largely sufficient at site 1 (7.56–9.23 mg/l), exceeding the minimum recommended threshold of 5 mg/l, while site 2 shows poor values (2.03–2.18 mg O₂/l), with a mean difference of 6.58 mg O₂/l between the two sites, indicating significant stress associated with a high organic load. Electrical conductivity is markedly higher at site 2 than at site 1, with a mean difference of 556.33 μS/cm, although remaining within the recommended range (100–2000 μS/cm). TDS (285–312 mg/l) and total hardness (252–291 mg/l as CaCO₃) exceed recommended values for tropical fish ponds (80–200 mg/l and 50–150 mg/l, respectively). Iron (3.0–3.2 mg/l) and manganese (0.2–0.4 mg/l) are elevated at site 1, whereas they remain within acceptable limits at site 2 (Fe 0.20–0.25 mg/l; Mn 0 mg/l). Cluster analysis (dendrogram) reveals homogeneous water quality at site 1 and heterogeneous conditions at site 2, as confirmed by Stiff and Schoeller diagrams, indicating stable mineralization at site 1 and critical nitrate and sulfate concentrations at site 2. The results show that both ponds have aquaculture potential, but with distinct constraints. Site 1 is weakly mineralized and characterized by elevated iron and manganese concentrations, requiring close monitoring and corrective management measures. In contrast, Site 2 has harder, better-buffered, and chemically more stable water, making it overall more suitable for sustainable aquaculture, despite low dissolved oxygen levels that can be corrected through appropriate management practices.Item Mobilisation communautaire des femmes rurales burundaises dans la lutte contre le paludisme : entre dynamiques sociales locales et efficacité des stratégies de prévention. Cas de la commune Busoni(UB, FLSH, 2025-12) Niyonkuru, Blandine; Sous la direction de : Dr. Aloys TOYIThis work explores the community mobilization of burundian rural women in the fight against malaria. The context is one of a major public health issue, characterized by a high prevalence of malaria, particularly in rural areas where access to health care and preventive measures is limited. Women play a crucial role in managing family and community health, yet their mobilization remains insufficiently exploited within prevention strategies. This study aims to analyze how women’s participation influences the effectiveness of local malaria control strategies, based on a qualitative approach conducted in Kirundo Province. It examines forms of social interaction, community organization, as well as local, social, cultural, and economic dynamics that facilitate or hinder their engagement. The main findings indicate that women’s mobilization, via social networks, community groups, and intra-familial interactions, has a positive impact on the adoption of preventive behaviors and community awareness. Communication and community solidarity reinforce their role in prevention, thereby contributing to increased resilience against the disease. However, sociocultural barriers, such as gender norms, still limit their access to resources. The thesis concludes that strengthening women’s participation in this fight is crucial and proposes actionable pathways for their empowerment and increased involvement. It also emphasizes that this approach can enhance the efficiency of prevention strategies in rural settings, by valorizing women as agents of change within their communities.Item Analyse des effets de seuil de l’aide publique au développement sur la croissance économique en Afrique (1996-2022)(UB, FSEA, 2025-06) Nduwimana, Jean Paul; Sous la direction du : Pr. Arcade NdoricimpaThe objective of this study is to analyze the threshold effects of official development assistance (ODA) on economic growth in African countries, categorizing them into two groups: low-income countries and middle-income countries. To achieve this, the study relies on data from the World Development Indicators (WDI), Worldwide Governance Indicators (WGI), and Penn World Table (PWT) covering the period from 1996 to 2022. It employs a panel threshold regression model (PTR) to determine, using the "Bootstrap" method, the threshold level of aid below which its effectiveness is manifested. The results of this analysis strongly support the idea that the relationship between aid and growth in Africa is non-linear, with a threshold of 23.07% of GDP. Beyond this threshold, aid becomes ineffective in stimulating growth, all else being equal. Furthermore, for low-income African countries, the ODA threshold is set at 31.33% of GDP, below which the effect on economic growth is positive, while above this, this effect becomes ineffective. For middle-income African countries, this threshold for official development assistance is 10.12% of GDP, below which ODA promotes growth, and beyond which its effect proves ineffective. After accounting for endogeneity using 2SLS and SGMM methods, the results suggest that the volume of ODA can be accumulated up to 23.07% of GDP in Africa; 31.33% of GDP for low-income countries and 10.12% of GDP for middle-income countries. These values represent the levels of ODA that should not be exceeded to ensure its effectiveness on economic growth.Item Effet de l’aide publique au développement sur le capital humain en Afrique subsaharienne : Le rôle de la qualité des institutions (1996-2023)(UB, FSEA, 2025-06) Dusabamahoro, Florence; Sous la direction du : Pr. Arcade NdoricimpaThe objective of this study is to analyse the effect of official development assistance (ODA) on human capital in sub-Saharan Africa over the period 1996 to 2023, focusing on the role of institutions in this relationship. To this end, the study uses dynamic generalised method of moments (GMM) panel data with annual series for 33 sub-Saharan African countries. The econometric estimates reveal a significant negative direct effect of ODA on human capital in sub-Saharan Africa. In addition, the results show a positive and significant direct effect of institutional quality on human capital in sub-Saharan Africa. The econometric estimates also show a positive and significant effect of the interaction between ODA and institutional quality on human capital in sub-Saharan Africa. In light of the results of this study, we suggest that governments invest in strengthening institutions, especially governance, public administration and the judiciary, in order to create sound and effective institutions that promote the best allocation of aid.Item Analyse économique de la culture du maïs et évaluation de l’effet du sarrasin comme engrais vert sur la culture du haricot à Kabarore ( KAYANZA, BURUNDI )(UB, FS, 2025-12) Nduwayo, Aimé Claude; Sous la Direction de : Pr Salvator Kaboneka (PhD)Burundian agriculture is largely dominated by subsistence family farming systems. It faces numerous challenges related to declining soil fertility, low yields of food crops, and the increasing impacts of climate change. In this context, the present study aims to analyze the economic profitability of maize ( Zea mays L.) cultivation and to assess the agronomic impact of using buckwheat ( Fagopyrum esculentum Moench) as green manure on the productivity of common bean ( Phaseolus vulgaris L.) in Kabarore Commune, Kayanza Province. The methodology adopted for this study combines experimental and economic approaches. Sixteen experimental plots belonging to different farmer-researchers were selected for maize cultivation, while four additional plots were used for bean cultivation. An economic analysis based on production costs and revenues was carried out in order to evaluate the profitability of maize cultivation under local conditions. The value–cost ratio (V/C) obtained for the sixteen farmers ranged from a minimum of 1.1 to a maximum of 5.6, with an average of 2.6. Based on the profitability criterion set at a minimum V/C of 2, it was observed that 14 out of the 16 farms studied (nearly 90%) exhibited good to very good economic profitability. As for the bean experment, field trials were established using a randomized complete block design to compare three treatments on dwarf bean (Mukungugu). In terms of average yield, the results revealed very low yield values: 56 kg/ha for T0 (absolute control + lime), 207.83 kg/ha for T1 (farmyard manure + Fomi-Imbura + lime), and 65.5 kg/ha for T2 [buckwheat (Fagopyrum esculentum Moench) + lime]. Although the trial can be considered an agronomic success, the results indicate that the buckwheat treatment was not more advantageous than the limed control treatment. Moreover, under the harsh conditions of the experiment (severe water deficit during the growing period), it was significantly inferior (by about 30%) to treatment T1 (farmyard manure + Fomi-Imbura + lime). At present, and without further repetition of the experiment, it is not possible to draw definitive conclusions about the fertilizing potential of buckwheat under the agro-ecological conditions of Kabarore Commune, Kayanza Province.Item La Mairie de Bujumbura : Gestion des espaces verts et ses incidences socio-économiques, de l’indépendance aux années 2000(UB, FLSH, 2025-04) Ntiranyibagira, Prosper; Sous la direction de : Dr. Niyongabo ThomasElements of culture and prestige, green spaces are, above all, a means of access for all or part of the population to a protected and maintained natural space, dedicated in particular to recreational or decorative purposes. Generally defined as “open and accessible spaces planted with plants”, green spaces include urban parks, monuments, gardens, playgrounds, street trees, etc.; green spaces play numerous roles in urban environments. In the urban planning of the city of Bujumbura, a legacy of colonization (now the economic capital of Burundi), the colonizers intended green spaces for a green urban living environment, allowing for relaxation and beautifying the city. It boasts green spaces linked to its political identity, historical and cultural monuments, and important plant landscapes that bear witness to the value of its past. To this end, it would be preferable to pay particular attention to this heritage with a view to preserving and enhancing it, as it can contribute, on the one hand, to stabilizing the foundations of the Burundian people's culture and identity, and, on the other hand, contribute as a source of income to the country's development. The city of Bujumbura must have a distinct architectural appearance, a green city adorned with trees and flowers, roads with clear rights-of-way allowing easy, unobstructed traffic, the area of various networks available to facilitate operation by network concessionaires, and buildings erected in strict compliance with standards and best practices. A city built according to a planned order with the aim of rationalizing green spaces and allowing for its growth.Item Assessment of the influence of food security, eating pattern and physical activity on nutritional status among lactating women in Bujumbura, Burundi(UB, EANSI, 2026-01) Mkwandu, L Victoria; Sous la direction de : Prof. Dr. Nahimana HilaireLactating women have increased nutritional requirements to maintain maternal health and support optimal infant growth. This study assessed the influence of food security, eating patterns and dietary diversity, daily physical activity on nutritional status among lactating women in Bujumbura. A one-month cross-sectional study using consecutive sampling was used. Data were collected using structured questionnaires on socio-demographic and obstetric characteristics, dietary diversity assessed by the Minimum Dietary Diversity for Women (MDD-W), food security classified according to WHO/FAO guidelines, physical activity measured in MET-minutes/week, and anthropometric measurements. Among 384 participants, 53.3% were aged 20-30 years, 92.7% were married, 64.8% were unemployed, and 72.7% had attained at least secondary education. Most women were 1-4 months postpartum (44.8%) and had fewer than three children (61.8%). Achieving minimum dietary diversity was protective against underweight (AOR = 0.274; 95% CI: 0.077-0.971; p = 0.045) and associated with overweight (AOR = 2.734; 95% CI: 1.053-7.097; p = 0.039). Low physical activity was associated with obesity (AOR = 19.774; 95% CI: 1.741-4.539; p = 0.016) and underweight (AOR = 7.8; 95% CI: 1.484-4.007; p = 0.015), while high physical activity was positively associated with dietary diversity (AOR = 8.918; 95% CI: 2.869-27.719; p = 0.001). Food security alone showed no significant association with nutritional status. Dietary diversity and physical activity were stronger determinants of nutritional outcomes than food security alone, highlighting the need for interventions promoting diverse diets and active lifestyles alongside food access programs.Item Inégalités sociales en matière d'accès aux soins de santé au Burundi: une étude sur l'accessibilité à la carte d’assurance maladie pour les groupes vulnérables de la commune Gisagara en province Buhumuza(UB, FLSH, 2025-11) Bimenyimana, Louis; Sous la direction de : Dr Soeur Rosette MinaniThis study examines social inequalities in access to hearthcare in Burundi ,focusing on the accessibility of hearth insurance cards for vulnerable groupes in commune Gisagara at BUHUMUZA province. The main research question explored why inequalities persist despite the legal obligation for every citizen to subscribe to health insurance.The results confirm that health insurance card significantly facilitates access to healthcare for vulnerable populations,validating the central hypothesis .However ,structural and socio- economic barriers sach as registration fees ,distance to health centers ,and administrations delays limit the effectiviness of this policy .Local health institutions play a crucial role in guiding and assisting beneficiaries ,yet their capacity is constrained by limitedlimited resources and staf shortages.Contraly to initial expectations ,discrimination based on residency and lack of information are not major obstacles ,as these minor hyopheses were disproved .Health policies theoretically address inequalities, but their implementation remains uneven and poorly adapted to local realities . The findind indicate that health insurance is an effective tool improving access to healthcare, but alone it con not eliminate disparities . The stady recommends strengthening local institutions, decentralizing services, and implementing targeted support measures to insure truly equitable access for vulnerable populations .Item Problématique de la mobilité urbaine : Cas de l’insecurité routière en mairie de Bujumbura (2010 - 2020)(UB, FLSH, 2022-01) Ciza, Diane; Sous la direction de : Pr. Ir. Bernard SindayiheburaThe city is a place of high concentrations of people who are subject to frequent displacement for various reasons. Means of transport are therefore very necessary to facilitate these daily trips. Modern life has multiplied these movements and tends to reinforce the distances to be covered. However, with the increase in the urban population and the vehicle fleet, we are witnessing congestion problems with considerable loss of time. The urban road in Bujumbura is ill-suited to the traffic it has to withstand in relation to all the means of transport superimposed on the same track. The growth of the vehicle fleet, the poor condition of the roads, their structure, the absence of bus stops, the insufficiency of adequate road signs increase the number of traffic accidents. The overall objective of this work is to contribute to the improvement of road safety in Bujumbura Town Hall. To achieve this goal, three specific goals have been set. The first specific objective is to identify the causes of road accidents in the city of Bujumbura in order to prevent the risks associated with them. The second is to show that the growth of the car park in the city of Bujumbura is obvious, while the last allows to assess the reception capacity of the urban road network in order to prevent feel the solutions that can increase its capacity to respond to surplus traffic. As part of this study, two hypotheses were put forward : H1. Road accidents are more frequent on primary roads. The superimposition of the different means of transport on the primary road is the main cause of these accidents. H2. The increase in the vehicle fleet is the cause of the accidents and congestion observed in the city of Bujumbura. The methodology used during this work consists of a qualitative approach based on the technique of direct observation. The results of this research showed that the primary roads of Bujumbura are saturated during peak hours (from 7 to 8 a.m. and from 5 to 6 p.m.) and that 67.5 of the accidents occur following collisions between two vehicles while overall, 87.3 of the accidents involve the vehicle component. Also, the cases of rolling accidents occur differ depending on the type of track. Thus, during the year 2019, 50.5 of accidents occurred on primary roads, 43.5 of accidents on secondary roads and the remaining 6 occurred in crossroads.Item Les jeunes vendeurs de crédits téléphoniques : entre survie et débrouillardise, étude menée dans la ville de Bujumbura(UB, FLSH, 2020-10) Ngoroyimana, Philémon; Sous Ia Direction de : Pr. Nicolas HajayandiThe worJd's population continues to grow. PoJjcies put in place to combat unemployment are not enough to find employment. ln this population, young people face many difficulties. ln Burundi, most of them leave the countryside for the city of Bujumbura in the hope of finding employment. From this generalized Jack of work, we notice a part of the youth that resists with small trades, including young people selling telephone credit. We are interested in the young people who practice this trade in order to understand how they fit into it, but also how they organize their work to adapt to the urban lifestyles of the city of Bujumbura. It is also a question of understanding the various perceptions ofthis activity, the identification ofthese young people in relation to their jobs, understanding the different career paths of the young people who engage in this activity, which influences their choice of sales outlets, their organization, their relations with their entourage, their appreciation of the profitabi litY of this profession and their plans for the future. By mobilizing the qualitative method to go down to the field to collect data, provided us with relevant data on the phenomenon under study. The results show us that we are facing a positive and resilient youth. The activity they carry out is underestimated and the young people who practice this profession are from the countryside. They came for their studies and started selling telephone credits; they have their diplomas and yet they find themselves in poverty and precariousness. They have been educated in the entrepreneurial sense because they did small commercial activities in their childhood. This is why they mastered the trade by choosing places with a large number of people, places where many people meet. These places of sale do not provide the same income and the young people find it difficult to satisfy their daily needs. As they have started, the young telephone credit salesmen plan to improve their jobs and hope one day to be hired to have a salaried job.Item Zone Buterere : Croissance urbaine et insalubrité(UB, FLSH, 2017-09) Kamikazi, Rosette; Sous la direction de : Professeur Manirakiza RenéCe travail de mémoire avait pour objectif d'appréhender la croissance urbaine et la gestion d'insalubrité dans la zone Buterere. La zone Buterere est une zone qui connaît des taux de croissance démographique important. En effet, la population augmente beaucoup et cela a un impact sur la gestion d'insalubrité dans cette zone. Le paysage urbain de Buterere est dégradé par une insalubrité accrue que ce soit au niveau du logement, assainissement tout cela dans un contexte des conditions sociodémographiques des populations de la zone Buterre qui sont défavorables. Bien que les mesures en vue de la gestion de l'insalubrité datent de longtemps, les résultats obtenus jusqu'à ce jour sont loin d'être satisfaisants dans la ville de Bujumbura et dans la zone Buterere en particulier. Aucun effort n'est ménagé par les structures compétentes que sont le ministère en charge de l'environnement, la mairie et l'administration locale pour une meilleure gestion d'insalubrité. Nos enquêtes sur le terrain nous ont révélé que la population font recours aux moyens de bords pour se débarrasser de diverses natures. Une sensibilisation de la population en matière d'hygiène est indispensable en vue de diminuer les risques d'insalubrité d'où la nécessite de la participation de plusieurs acteurs pour la gestion d'insalubrité.Item Effet de l'inflation sur la croissance économique et le bien-être des habitants au Burundi (1988-2013)(UB, FSEA, 2016-02) Butoyi, Henri; sous la direction de : M. Désiré NkurunzizaItem Essai d'évaluation des performances de l'E.P.B par des critères non exclusivement financiers(UB, FSEA, 2012-09) Nkurunziza, Dieudonné; Sous la direction de Dr Déo BanderembakoItem Les smectites du Burundi : caractérisation ; génèse ; aspects géotechnique, agricole et industriel(UB, FS, 1992) Bucumi, Alexis; Sous la direction de : Luc TackItem Etude comparative de la structure et de l'évolution de deux forêts claires à branchystegia près de Rumonge(UB, FS, 1994-03) Nduwimana, André; Soùs la direction du : Prof. Dr Bart BuyckItem Glissements de terrain dans le bassin versant de la rivière Gikoma : des processus aux effets(UB, FLSH, 2015-09) Sindayihebura, Jean François Régis; Sous la direction de : René ManirakizaItem Impact de l’accumulation en certains métaux lourds (cuivre, zinc et plomb) dans les amarantes irriguées de la ville de Bujumbura(UB, EANSI, 2025-08) Niyomutoni, Astérie; Sous la direction de : Pr. Dr. Ir Niyukuri JonathanHeavy metals, such as mercury, chromium, cadmium, arsenic, and lead, are toxic elements that accumulate in the food chain, harming living organisms even at low concentrations. In the city of Bujumbura, the use of wastewater to irrigate amaranth plots leads to contamination, which can cause illness among consumers. The overall objective of this study is to assess heavy metal contamination in amaranth cultivated in Bujumbura, by analyzing the concentration levels of these contaminants. The study was conducted in four areas of Bujumbura City Hall such as Buterere, Buyenzi, Musaga where amaranth farmers use wastewater for irrigation, and a control site at the Mutanga campus using tap water. The heavy metals analyzed include Cu, Pb, Zn, and Cd. This study highlights the impact of irrigation water on crop contamination. Data collection began with the preparation of control fields in the MUTANGA campus greenhouse, followed by the collection of amaranth leaves in the four study areas, including the control site. Samples of 500 g of amaranth leaves were collected in triplicate. Mineral element analysis was performed using flame atomic absorption spectrophotometry at ISABU, and data analysis was carried out using SPSS version 20 software. Physicochemical analysis shows that heavy metal levels vary depending on the growing site and the quality of the irrigation water used. The levels ranged from Mutanga to Cu=4.55 mg/kg, Pb=9.83 mg/kg, Zn=38.96 mg/kg, and Cd≤0.1 mg/kg, respectively, for Cu, Pb, Zn, and Cd in the control samples; 7.42mg/kg, Pb=11.66mg/kg, Zn=67.68mg/kg, Cd≤0.1mg/kg respectively for Cu,Pb, Zn and Cd for samples from Buyenzi; 5.60mg/kg, Pb=11.42mg/kg, Zn=80.91mg/kg respectively for Cu, Pb, Zn and Cd for samples from Buterere and Cd≤0.1mg/kg and Cu=6.75mg/kg, Pb=14.42mg/kg, Zn=61.00mg/kg and Cd≤0.1mg/kg respectively for Cu, Pb, Zn and Cd for samples from Musaga. These results highlight the impact of irrigation water on heavy metal contamination. The sampling sites exhibited higher levels of heavy metal contamination compared to the MUTANGA control site, due to the quality of the irrigation water.Item Etude comparative de la papaïne et de la Bromélaïne comme coagulants alternatifs pour la transformation des produits laitiers : Cas du fromage du type Gouda(UB, EANSI, 2025-07) Ngabirano, Elie; Sous la direction : Pr Nzigamasabo AloysProteins are essential nutritionally, economically, and sociocultural, and are especially present in ruminant milk, whose processing into cheese allows for better preservation. Rennet, a coagulating enzyme extracted from the stomachs of young ruminants, mainly milk-fed calves, is most often used in cheese processing, making it expensive and limited in availability. The study demonstrates that papain and bromelain can coagulate cow's milk, with variable results depending on the quantity used, and the processed cheeses retain their organoleptic qualities for 9 months of ripening and more. FP1 cheese, coagulated with 1 g of papaya leaves, did not form a curd, while at 3 g, an adequate curd formed. FA2 cheese, made with 40 ml of pineapple juice, was rated higher in taste, odor, and color than the one coagulated with 3 g of papaya leaves. A low dose of enzymes is recommended to preserve the organoleptic quality of the cheese. Although papain has superior proteolytic activity, bromelain is preferred for its sensory qualities. This study represents the first investigation into the production of Gouda cheese using natural coagulants, although challenges remain regarding enzyme extraction and the texture of the final product. Microbiological analysis reveals the absence of harmful staphylococci and coliforms, but a high presence of lactic acid flora and slight contamination by yeasts and molds. Ripening conditions influence microbial growth.