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ItemEvaluation of Market Waste as a co-substrate for enhanced biogas production: Case of Kasubi C/U Primary School(Makerere University, 2026-09)Urban sanitation in sub-Saharan Africa remains a critical public health challenge, with large volumes of faecal sludge generated daily in densely populated cities presenting both a management burden and an untapped resource for renewable energy recovery. Bio-latrine systems, which treat faecal sludge anaerobically to produce biogas, have emerged as a promising technology for simultaneously addressing sanitation and energy needs in institutional settings. However, mono-digestion of faecal sludge is often constrained by its low carbon-to-nitrogen ratio, resulting in poor biogas yields that undermine the economic viability of these systems. Co-digestion with carbon-rich organic substrates offers a practical solution to this limitation, and the large quantities of biodegradable market waste generated in urban areas present a locally available and largely untapped co-substrate opportunity. This study therefore evaluated the potential of jackfruit peel waste from Kasubi Market as a co-substrate for enhancing biogas production from faecal sludge, using the institutional bio-latrine system at Kasubi Church of Uganda Primary School in Kampala, Uganda as the case study. A market waste composition study conducted at Kasubi Market established that jackfruit peel waste constituted the largest fraction of the waste stream at 36.65% of total waste generated, with an estimated daily availability of 1,900–2,160 kg, approximately five to six times the quantity required to sustain the digester. Physicochemical characterisation revealed complementary substrate properties: faecal sludge had a C/N ratio of 12.1:1, well below the recommended range of 20–30:1, while jackfruit peel waste recorded a high C/N ratio of 48.8:1, with volatile solids contents of 78.65% and 95.75% respectively, confirming their suitability as anaerobic digestion feedstocks. Biochemical methane potential (BMP) experiments were conducted at five jackfruit peel waste to faecal sludge mixing ratios under mesophilic conditions (37°C). Biogas yield data were fitted to a quadratic mixture model using Design-Expert software, which was statistically significant (F = 7.61, p = 0.0304, R² = 0.7526). The 50:50 jackfruit peel waste to faecal sludge ratio achieved the highest experimental biogas potential of 517.51 mL/g VS, with a maximum production rate of 58.53 mL/g VS/day among the co-digestion ratios. Numerical optimisation using the desirability function approach identified the optimal mixing ratio as 38.4% jackfruit peel waste and 61.6% faecal sludge, with a predicted biogas yield of 586.39 mL/g VS at a desirability value of 0.971. Process stability monitoring confirmed that all co-digestion ratios maintained VFA/alkalinity ratios well below the 0.4 threshold throughout the experiment, while mono-digestion of jackfruit peel waste alone resulted in severe acidification and process failure. These findings were derived from batch experiments and would require validation under continuous feeding and pilot-scale conditions before full implementation. The study confirms that co-digestion of faecal sludge with jackfruit peel waste from Kasubi Market is a technically viable, cost-effective, and locally appropriate strategy for improving biogas recovery in institutional bio-latrine systems, addressing both the school's energy needs and the market's waste management challenge simultaneously.
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ItemDesign and assessment of earth-air heat exchanger as an intergrated natural cooling system for net zero tropicl buildings.(Makerere University, 2026-09-11)Earth Air Heat Exchangers (EAHE), represent a promising passive technology for addressing cooling and heating needs in buildings by utilizing the earth's stable subsurface temperature. EAHEs have been extensively used for both space heating and cooling over the course of many years, and this topic remains attractive to researchers. Intensive studies have been carried out on this topic concerning the heat and mass transfer characteristics of the EAHE, design and operational parameters, energy saving potential, feasibility study in different climates and buildings and thermal performance of hybrid EAHE systems (Zhao et al., 2024). At depths between 1 to 4 meters below the ground surface, soil temperatures remain relatively constant throughout the year, typically ranging between 10-25°C depending on geographic location and climate zone (El Khachine et al., 2024). This thermal stability provides a natural heat sink for cooling in dry/hot season and a heat source for warming in cold (Peñaloza Peña et al., 2021). The use of EAHE systems for air conditioning in commercial and industrial settings offers several environmental benefits and is capable of operating in both standalone and hybrid modes (Lattieff et al., 2022). The advantages of EAHE systems are particularly relevant for low-income tropical contexts. These systems require no compressors, refrigerants, or fossil fuel combustion, with only low-power fans or blowers needed to circulate air. This translates to minimal operational costs and maintenance requirements compared to conventional air conditioning. EAHE systems can reduce cooling energy demand by 20-30% while simultaneously improving indoor air quality through continuous fresh air ventilation (Li et al., 2023). The technology is compatible with locally available materials and low-skill construction techniques, making it accessible for implementation in resource-constrained settings. Research across various climate zones has demonstrated the effectiveness of EAHE systems. Studies in tropical and hot-arid climates have shown temperature reductions of 10-16°C during peak summer conditions. The design of net zero buildings incorporating natural temperature harnessing technologies like EAHE systems represents a critical intervention point for low-income tropical regions. By dramatically reducing cooling energy demand through passive strategies while providing affordable, renewable-powered thermal regulation, these buildings can break the cycle of energy poverty, improve health and well-being, and contribute to global climate mitigation efforts. This project explores the technical, economic, and social dimensions of integrating EAHE technology within comprehensive net zero building designs tailored to the specific needs and constraints of low-income tropical communities, contributing to the broader global imperative of achieving universal access to sustainable, healthy, and climate-resilient buildings.
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ItemAssessment of the influence of road geometric design parameters on crash frequency and severity at Bwaise interchange(Makerere University, 2026)Road geometric design parameters are fundamental determinants of road safety, governing vehicle operating speeds, driver workload, braking performance, and the margin available for collision avoidance. Deficiencies in horizontal curvature, longitudinal gradient, lane width, and intersection configuration systematically elevate both crash frequency and severity, yet localized quantitative analyses linking such deficiencies to crash occurrence at urban hotspots in Uganda remain scarce. This study assessed the influence of road geometric design parameters on crash frequency and severity at Bwaise interchange, Kawempe Division, Kampala, over the period 2020-2024. Twenty segments, ten circulatory arcs, and ten approach/exit arm segments produced a panel of 100 segment-year observations from 74 spatially confirmed crash events sourced from Kawempe Police Station and the KCCA Bloomberg Road Safety Database. Geometric parameters were extracted from Ministry of Works and Transport as-built drawings and Google Earth Pro profiles, with spatial allocation in ArcGIS Pro 3.4.2. Poisson, Negative Binomial, and Zero-Inflated Negative Binomial regression were employed for crash frequency, ordered logistic regression for severity, and Crash Modification Factors derived from model Incidence Rate Ratios using the AASHTO Highway Safety Manual framework. The study recorded a mean crash rate of 21.01 crashes per kilometer per year across 20 segments, with four primary hotspots identified. Damage-only crashes dominated at 65.92%, while 18.1% involved injury or fatality; all recorded fatalities occurred on approach arm segments with steep gradients, three of which exceeded the recommended maximum of 4%, the worst recording 7.01%. The Negative Binomial model was confirmed as the most appropriate crash frequency estimator. Each one percentage point increase in longitudinal gradient was associated with a 17.8 -19.5% increase in expected annual crash count. Horizontal curve radius was the strongest geometric predictor, with each one-meter increase reducing expected crashes by 2.9-5.0% (r = -0.675). Crash Modification Factor analysis indicated that gradient reduction from 7.01% to the recommended 4.0% was associated with a 39-41% crash reduction, the single highest-impact intervention at the junction. Ordered logistic regression confirmed gradient and curve radius as significant predictors of crash severity. These findings confirm that geometric design non-compliance is systematically associated with elevated crash frequency and severity at Bwaise interchange.
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ItemFlood forecasting and early warning In Nyamwamba river catchment using machine learning(Makerere University, 2026-06)The Nyamwamba River Catchment in Kasese District experiences frequent, destructive flash floods driven by steep topography, heavy rainfall, and climate variability, exposing critical vulnerabilities in regional disaster management due to sparse gauging infrastructure and reactive response mechanisms. This study develops an integrated machine learning-based flood forecasting and early warning framework to quantify flood risk in the Nyamwamba catchment and to provide timely, location-specific warnings for vulnerable downstream communities. Predictive modeling using Extreme Gradient Boosting (XGBoost)—incorporating binary classification for flood occurrence and regression for river discharge prediction—was forced with multi-source meteorological and remote sensing data (ERA5-Land baseline 2000–2025 and Open-Meteo APIs), utilizing engineered hydrological features such as antecedent precipitation indices, rolling statistics, and flash-flood threats. Spatial flood routing and overland flow simulations were further conducted within an ArcGIS environment to evaluate catchment response times and critical lead intervals under high-intensity precipitation scenarios. Outputs included optimized XGBoost classification and regression models, a real-time operational forecasting pipeline, GIS-based spatial flood simulations demonstrating sub-hourly catchment response times, and an automated multi-channel early warning platform capable of dispatching instant SMS and email alerts to at-risk stakeholders.
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ItemAssessment of flow variability and operation efficiency for the Nyagak run of rivers hydropower plant in Zombo district.(Makerere University, 2026-06)The Nyagak Run-of-River Hydropower Plant (6.6 MW) in Zombo District depends entirely on natural river inflows, making its generation performance highly sensitive to seasonal variability and climate change. This study develops an integrated continuous hydrological–operational modelling framework to quantify flow variability in the Nyagak catchment (≈590km²) and to assess its influence on daily power production. Continuous simulation using HEC-HMS (Deficit and constant, baseflow recession and Clark Unit Hydrograph as the transform method) was forced with observed station and gridded rainfall/temperature data (baseline 2000–2025), calibrated (2000–2019) and validated (2020–2025). Climate-adjusted inflows were generated using bias-corrected CORDEX-Africa projections under RCP4.5 and RCP8.5. Outputs included a calibrated continuous hydrological model for the Nyagak catchment, daily inflow time-series for baseline and future scenarios, daily power production estimates computed from simulated flows, and scenario comparisons of generation reliability under low- and high-flow conditions.