https://dr.ur.ac.rw/handle/123456789/27 Research works from students of the College of Science and Technology 2026-05-20T16:16:26Z https://dr.ur.ac.rw/handle/123456789/2929 Investigation on the capability of Rwandan Macrophytes: Cyperus papyrus and Leersia Hexandra to treat polluted water and wastewater UWIMANA, Jean Pierre The paint industry's wastewater effluents contain persistent metals that pose significant environmental risks. Conventional treatment methods for the contaminated area, including soil and rivers, are often inadequate. Searching for new alternative solutions is of high interest. This study explores the potential of indigenous Rwandan macrophytes, C. papyrus (CP) and L. hexandra (LH), as sustainable adsorbents. This study assesses CP and LH powder, non-activated biochar, activated biochar, and cellulosic materials derived from these macrophytes as latent options in order to eliminate heavy metals such as cadmium (Cd) and Lead (Pb) from wastewater. Prepared adsorbents were chemically characterized using FTIR spectroscopy, while the effectiveness of eliminating heavy metals was assessed through Atomic Absorption Spectrophotometry. The parameters for adsorption were refined, and the kinetic information was adjusted to align using models of the second and pseudo-first order. The efficiency of the adsorption process was evaluated using both batch and packed bed experiments. Furthermore, the Freundlich and Langmuir isotherms were analyzed, and the thermodynamic parameters were examined. Cellulosic materials were extracted with yields of 40.2% and 35% for CP and LH, respectively. The ideal conditions for adsorption included a pH level of 6, an adsorbent quantity of 1.5 grams, a contact duration of two hours, and an initial concentration of metal at 10 ppm. The removal efficiencies of CP and LH powder were evaluated at percentages 57.6% and 60.1% for Pb and 56.1% and 56.6% for Cd. CP and LH non-biochar were 67.5% and 55.2% for Pb while 61.1% and 50.5% for Cd. on activated biochar were CP 92.2% Pb, 89.9% Cd; LH 89.9% Pb, 86.3% Cd. The removal efficiency of extracted cellulosic material from CP was 78.8% for Pb and 76.7% for Cd while extracted cellulosic material from LH was 73.2% for Pb and 71.2% for Cd, respectively. Nonetheless, Kinetic studies confirmed pseudo-second-order (PSO) behavior (R² > 0.98), indicating chemisorption, while Freundlich isotherms suggested heterogeneous, multilayer adsorption. Thermodynamic analysis revealed the non-spontaneous, endothermic adsorption process. Overall, findings support the use of CP and LH-derived materials serving as efficient and economical adsorbents for cleaning industrial wastewater tainted with heavy metals. Master's Dissertation 2025-06-05T00:00:00Z https://dr.ur.ac.rw/handle/123456789/2923 Improving power quality in mini-grid by integration with solar power system using predictive control: a case study of Nyankorogoma hydro mini-grid HABUMUGISHA, Daniel The growing need for sustainable and reliable electricity in rural areas has led to the integration of renewable energy sources into mini-grids. However, power quality challenges arise due to fluctuations in solar irradiance and hydro resource availability. This study addresses these challenges by implementing Model Predictive Control (MPC) to optimize energy flow in the Nyankorogoma hydro mini-grid, enhancing voltage stability and reducing power losses. A mathematical model of the hybrid solar-hydro system was developed and simulated in MATLAB/Simulink, incorporating real operational data from Nyankorogoma. The MPC algorithm was applied to control a boost converter, ensuring smooth solar power integration. Simulation results demonstrate that MPC effectively mitigates voltage fluctuations and reduces Total Harmonic Distortion (THD), improving overall power quality. FFT analysis revealed a reduction in THD from 12.07% to 4.02% after implementing MPC, indicating a significant improvement in waveform quality. Additionally, energy previously lost in dump loads was redirected for productive use, increasing system efficiency. The findings confirm that MPC-based solar integration enhances mini-grid stability, making it a viable solution for renewable energy-based rural electrification. Further research should explore real-world implementation, battery storage integration, and artificial Neural network driven predictive control for improved energy management. Master's Dissertation 2024-10-02T00:00:00Z https://dr.ur.ac.rw/handle/123456789/2922 Energy audit and conservation for industry sector in Rwanda: case study: Sulfo Rwanda industries ltd NIYIREMA, Jonas Energy efficiency is a fundamental pillar of industrial sustainability, directly influencing both operational costs and environmental impact. This study explores energy audit and conservation practices in Rwanda’s industrial sector, with a particular focus on SULFO Rwanda Industries Ltd. The research addresses the pressing issue of inefficient energy consumption, largely attributed to outdated equipment, inadequate maintenance, and the absence of systematic energy management. Through comprehensive data collection, energy consumption analysis, benchmarking against global standards, and simulations using RET Screen Expert software, this study evaluates the potential for improving energy efficiency. The findings highlight significant inefficiencies, with energy consumption in PET bottle production and soap manufacturing exceeding international benchmarks by 92.8% and 5.66%, respectively. By implementing targeted measures such as upgrading motors, optimizing lighting systems, and refining production processes, the study identifies opportunities for substantial energy savings estimated at 20,317 kWh annually alongside a cost reduction of approximately 2,499,005 RWF. These insights underscore the critical need for industries to integrate energy-efficient technologies and adopt real-time energy monitoring systems. The study concludes that fostering collaboration between industries and policymakers, enforcing regulatory energy audits, and investing in sustainable technologies can drive Rwanda’s industrial sector toward greater energy efficiency and long-term economic and environmental sustainability. The recommendations presented offer a strategic framework that can be adapted to similar industrial settings, supporting Rwanda’s broader transition to a green economy. Master's Dissertation 2025-10-03T00:00:00Z https://dr.ur.ac.rw/handle/123456789/2921 Assessment of power losses and efficiency improvement of Rwandan transmission line using FACT Device. Case Study: Musha-Rwinkwavu transmission line NUMVIYINGOMA, Théophile The Rwandan power grid faces significant challenges related to power losses and inefficiencies across its entire system, from generation, transmission, and distribution. The grid consists of 36 substations and 49 power plants spread across various regions of the country. The transmission network primarily operates at 110 kV, with some lines at 220 kV. Power losses are a critical issue that needs to be addressed to enhance the Available Transfer Capability of power systems. Mitigating these losses involves a two-stage process: The Planning phase and the Operational phase. In the Planning phase, strategies are developed to minimize losses before they occur. This includes the design and optimization of the power system infrastructure, such as selecting the appropriate size and type of conductors, transformers, and other equipment. Additionally, planning for future load growth and potential system expansions is crucial to ensure that the system can handle increased demand without significant losses. During the Operational phase, the focus shifts to real-time management and optimization of the power system. Techniques such as dynamic power flow control, real-time monitoring, and load balancing are employed to minimize losses as electricity is transmitted from generation points to end-users. As the load on the transmission system varies, the system operates under stressed conditions, which can lead to potential failures and increased losses. Effective power flow control techniques help to manage these variations and maintain system reliability. This research evaluates the efficiency of Transmission line Musha-Rwinkwavu according to accepted standards. This involves determining the amount of power lost during the transfer of energy through the electrical network from generation to distribution. By quantifying these losses, improvements opportunities have been studied. Additionally, techniques for mitigating power losses and enhancing voltage profile by including STATCOM were explored. Addressing the challenges of power losses and inefficiency on transmission line MushaRwinkwavu if feasible by using a STATCOM of 1.3MVA and losses which are on 4% reduced up to 3%. Master's Dissertation 2025-10-01T00:00:00Z