Botswana International University of Science and Technology
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Item type:Item, Development of membranes from coal-derived Graphene Oxide for organic dye removal in wastewater treatment(Botswana International University of Science and Technology, 2025-08) Marakalala, Boitshepo Ivy; Kandjou, Vepika; Ntuli, FreemanCoal, though abundant, faces increasing restrictions due to its environmental impact as a fossil fuel. However, its carbon-rich nature presents opportunities for sustainable valorisation. This study explores the transformation of Botswana’s coal fines, an underutilized waste product, into valuable carbon nanomaterials, specifically graphite and graphene oxide (GO). Graphitization of coal fines was followed by GO synthesis using an optimized version of the improved Hummers’ method, producing highly hydrophilic GO with an oxygen content of up to 40.7 %. Comprehensive characterization techniques, including FTIR, Raman spectroscopy, and SEM-EDX, confirmed the compositional and morphological integrity of the graphite and GO. The synthesized GO was then used to fabricate membranes via a dead-end filtration method, with varying GO concentrations. These membranes demonstrated exceptional performance in removing Methylene Blue dye, achieving up to 99.8 % rejection, porosity of 13.2 %, and flux ranging from 0.62 to 17 L/m2.hr. Additionally, a fouling resistance of 0.087 m2.hr.bar/L indicated strong potential for long-term application. The findings highlight a cost-effective, environmentally friendly pathway for converting coal waste into purposeful GO membranes, designed for advanced water purification applications through selective dye removal mechanisms such as π-π interactions.Item type:Item, Investigating the potential of biogas production from BIUST wastewater treatment sludge by co-digestion with slaughterhouse waste(Botswana International University of Science and Technology, 2024-07-22) Othusitse, Nhlanhla; Dlamini, Gcinumuzi; Jonas, Mbako; Mamvura, Tirivaviri; Agachi, Paul S.Wastewater treatment is a necessity in any community and civilization particularly where water is a scarce natural resource. The Botswana International University of Science and Technology is habitat to a community of just under 5000 people and has its own dedicated wastewater treatment plant. Currently this plant is managed by the university and boasts of 7 ponds. The plant follows a conventional four stage process; starting off with screening and grit removal, then removal of suspended solids through sedimentation, breakdown of organic matter through biological processes, then lastly filtration, disinfection, and use of chemical treatment to ensure compliance with quality standards before final discharge. This research aims at the third stage of biological processing to explore potential for biogas production potential from BIUST wastewater treatment sludge (WTS). Presently the anaerobic digestion ponds are open to the atmosphere and therefore release methane to the atmosphere adding to greenhouse gas emissions. To investigate, four different ratios of sludge (SL) to slaughterhouse waste (SHW) (1:1, 1:3, 3:1, 2:3) were co-digested, and the two substrates mono digested. The experiment was conducted over a retention time of 32 days in 2L reactor vessels. The results for bio-methane potential revealed that sludge: slaughterhouse waste 1:3 accumulated the highest volume of biogas (10,446.4 NmL CH4/gVS), sludge on its own accumulated the lowest volume of biogas (3,134.9 NmL CH4/gVS). The ratio of 2:3 exhibited the most optimal physiochemical properties for biogas production, promising a high turnover of gas produced. The premeditated assumption was later discovered to be false, as the volume accumulated was relatively low (3435.8 NmL CH4/ gVS) only increasing by 9.6% compared to the lone digestion of sludge. Ratio of 3:1 yielded a biogas of 5,686.1 NmL CH4/gVS, showing an 81% increase in biogas yield compared to mono-digestion of sludge. Therefore, co-digestion of sludge with slaughterhouse waste at a 3:1 ratio shows great potential for biogas production from BIUST waste treatment sludge.Item type:Item, Hybrid machine learning and genetic algorithms for environmental impact and energy management to enhance mining sustainability(Botswana International University of Science and Technology, 2024-07-22) Parvathareddy, Sravani; Yahya, Abid; Amuhaya, Lilian Livutse; Ravi, SamikannuThe mining industry confronts the challenge of balancing economic prosperity and environmental sustainability. This research presents a comprehensive approach that leverages big data analytics and machine learning techniques to address this challenge. Unlike traditional approaches that focus on mitigating impacts post-occurrence, our method advocates for proactive measures throughout operational phases. We introduce a cohesive system integrating advanced technologies to analyze vast datasets, including real-time environmental sensor data, satellite imagery, company reports, and government records. The framework encompasses data pre-processing, model building, analysis, and recommendations. To predict environmental outcomes and assess sustainability, we employ a genetic algorithm (GA) and machine learning tools such as XGBoost, support vector regressor (SVR), and K-nearest neighbors (KNN) regressor algorithms. Data pre-processing ensures data accuracy and consistency. We use clustering and recommendation algorithms for analysis and suggestions, identify improvement areas, and propose environmental management solutions. This methodology underscores the importance of empowering stakeholders to anticipate environmental consequences, mitigate potential hazards, and continuously improve sustainability initiatives through real-time insights. By integrating big data analytics and machine learning, we enhance the environmental sustainability of mining operations, fostering a harmonious balance between environmental stewardship and economic returns. The benefits of our system are manifold, including improved environmental management, reduced environmental risks, and enhanced sustainability practices in the mining industry, thereby highlighting the crucial role of stakeholders in this process.Item type:Item, Physiological and ecological responses of the larger grain borer, Prostephanus truncatus (Horn), to changing environments: implications for its population dynamics and management(Botswana International University of Science and Technology (BIUST), 2025-09) Mlambo, Shaw; Nyamukondiwa, Casper; Machekano, Honest; Mvumi, BrightonThe rapid change in environments owing to anthropogenic activities and climate change has reshaped the geographical range and status of different insect pests of economic importance. Further, the mechanisms by which conspecific and allospecific species phenotypes vary and how that influences species adaptation in novel environments are poorly understood. The larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), is one of the quarantine pests which poses serious threats to stored maize and dried cassava tubers and has continued to expand its ranges in Africa. However, physiological and ecological data required to map the dispersal pathways and factors limiting geographical distribution of such pests in diverse environments are largely understudied. A combination of literature reviews, field (questionnaire survey and pest monitoring through pheromone baited traps) and laboratory studies were conducted to determine (i) the presence and geographical range of P. truncatus in Botswana (Chapter 2), (ii) local farmers’ knowledge, practices and perceptions on cereal postharvest management including the efficacy of current storage technologies against P. truncatus (Chapter 3), (iii) the drivers and implications of P. truncatus and Spodoptera frugiperda biological invasions in Africa (Chapter 4), (iv) effects of increasing temperatures on the transgenerational (Chapter 5) and intergenerational (Chapter 6) responses of P. truncatus, (v) feeding rates and effects of maternal host preferences on progeny fitness (Chapter 7) and (vi) effects of intra- an interspecific competition on P. truncatus’ physiological and ecological performance (Chapter 8). Standardised physiological (critical thermal maxima [CTmax], critical thermal minima [CTmin], heat knockdown time [HKDT], upper lethal temperatures [ULTs]) and ecological performance (% maize grain damage, % grain weight loss, progeny production, % insect feeding dust) traits were measured under controlled temperature and relative humidity conditions in climate chambers. Results confirmed, for the first time, the presence of P. truncatus in Botswana, but its distribution is still patchy. Although the pest seems not yet well-established inland, the current farmer practices dominated by use of botanical pesticides makes them vulnerable if P. truncatus was to become dominant. Lack of information and awareness of the dangers that P. truncatus pose and lack of improved grain storage facilities further expose local smallholder farmers to this threat. Laboratory assays showed behaviourally plastic responses to increased temperatures and varying xvii hosts. First, trait-dependent thermal plasticity responses are passed on to offspring through transgenerational and intergenerational plastic physiological responses which mediate P. truncatus progeny fitness. Alongside, maternal experiences or decisions by offspring through transgenerational plasticity act as signals for adaptation to a host. Ecological performance of P. truncatus was high at 25 and 30℃ in response to temperature suggesting high pest activity under elevated temperature conditions. This may mean that P. truncatus poses serious threats to food security with increasing temperatures under climate change. However, damage was highly suppressed at higher suboptimal temperatures of 35℃. Prostephanus truncatus failed to survive on mopane wood suggesting that the wood may not be a suitable host for the pest. The study shows P. truncatus physiological adaptative responses to changes in the environment and climate and calls for concerted efforts to monitor the pest inland, forewarn farmers of the dangers of the pest and train them on appropriate efficacious grain storage technologies to manage the pest. This work contributes insights into the ecology and physiology of P. truncatus, which are important in developing models for early warning and control, as well as integrated national and regional pest management strategies against the pest.