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Item Unprecedented Burning in Tropical Peatlands During the 20th Century Compared to the Previous Two Millennia(John Wiley and Sons Inc, 2026-03-17) Wang, Yuwan; Feldpausch, Ted; Swindles, Graeme; Moss, Patrick; McGowan, Hamish; Sim, Thomas; Morris, Paul; Benfield, Adam; Courtney‐Mustaphi, Colin; Wahl, David; Montoya, Encarni; Githumbi, Esther; Coronado, Eurídice; Augustijns, Femke; Verstraeten, Gert; Donnell, Jess; Tibby, John; Benavides, JuanTropical peatland wildfire incidence has risen in recent decades, driven by drainage for land use and intensified by severe droughts with global climate change. These disturbances have altered vegetation structure, disrupted ecosystem functioning, and increased carbon emissions, particularly in Southeast Asia. However, the long-term history and characteristics of wildfires in tropical peatlands remain largely unknown. Here, we compiled fifty-eight macro-charcoal records from peatlands across the tropics, ranging from lowland forested to montane peatlands, to assess millennia-scale changes and controlling factors of tropical peatland burning. We divided the datasets into four main sub-regions: Neotropical, Afrotropical, Indomalayan and Australasian ecoregions to explore regional variability. Tropical peatlands had high burning levels between 0 and 850 ce, followed by a relatively low and stable period until a marked increase during the 20th century. The general trend in tropical peatland burning follows changes in global temperature, and climate variables that control the length and severity of drought events have a notable influence on peat burning before 1900 ce. During the 20th century, regional differences were observed, with declining fire trends in the Neotropical and Afrotropical regions and increasing fire trends in the Indomalayan and Australasian regions. This difference is likely attributable to human activities, and such intervention is also evident in palm swamps and hardwood swamps under similar wet, weakly seasonal climates. With the increase in anthropogenic pressures on peatlands and greater climate variability, future wildfires in peatlands are likely to become more frequent and widespread across all tropical ecoregions. Conservation and sustainable land-use practices could be used to mitigate and control peatland burning and protect these carbon-rich sinks.Item Rare earth element systematics–based multi-tracer hydrogeochemistry reveals controls on potentially harmful inorganic constituents in groundwater from a volcanic rift system in Tanzania(Elsevier, 2026-05) Nakaya, Shinji; Masuda, Harue; Yasumoto, Jun; Sakakibara, Koichi; Takada, Ryogo; Shinjo, Ryuichi; Lugodisha, InnocentThis study investigated potentially harmful inorganic constituents (PHICs) and the hydrogeochemical properties of drinking water from wells in a densely populated area on the slopes of Mount Meru in the East African Rift Valley. A multi-tracer approach, including rare earth elements (REEs), strontium isotope ratios, and stable oxygen and hydrogen isotope ratios (δ18O and δD), was applied to elucidate groundwater sources and controlling processes in the volcanic area. Groundwater is enriched in light REEs (La–Nd) and exhibits a positive Gd anomaly, interpreted as being of geogenic origin. Integration of REE systematics, Sr isotope signatures, and groundwater flow-path length indicators inferred from δ18O and δD suggests interaction with rocks derived from highly differentiated volcanic lithologies and reveals two distinct groundwater flow systems characterized by contrasting leaching and transport behaviors of potentially toxic trace elements. REE patterns indicate that six of eighteen well water samples are influenced by surface water infiltration. This surface contribution dilutes Fe and Pb concentrations, whereas fluoride (F−) remains largely unaffected, while nitrate (NO3−) increases with increasing infiltration, reflecting superimposed anthropogenic inputs. Notably, elevated concentrations of PHICs (Fe, Pb, F−, and NO3−) exceeding World Health Organization drinking-water guideline values were detected in several residential wells (8/18 for Fe, 7/18 for Pb, 13/18 for F−, and 6/18 for NO3−). The lack of systematic covariation between NO3− and Cl− concentrations, and Pb, Fe, and CI chondrite–normalized REEs supports a predominantly geogenic control on Pb, Fe, and REE. Overall, this study demonstrates that integrated geochemical tracers provide a robust framework for disentangling geogenic and anthropogenic controls on groundwater quality in volcanic rift settings.Item Mechanical, durability, and thermal performance of concrete incorporating coffee biochar and raw and calcined montmorillonite(Frontiers, 2026-04-21) Hepautwa, Amani; Hilonga, Askwar; Mrosso, Register; Alfredy, Tusekile; Lesafi, Fina; Jande, YusufuIntroduction: Montmorillonite is a natural aluminosilicate clay with potential as a supplementary cementitious material, although its reactivity in the raw state is limited. This study investigates the effect of raw and calcined montmorillonite on the performance of concrete incorporating 15% pyrolyzed coffee grounds (PCG) at 350 °C.Methods: Montmorillonite calcined at 400, 600, and 800 °C replaced cement at levels of 5%–20%. Mechanical and durability properties were evaluated under acidic, saline, and thermal exposure conditions. Microstructural characterization was conducted using FTIR, XRD, and SEM, and statistical validation was performed using two-way ANOVA.Results: Calcination enhanced montmorillonite reactivity through amorphization and pozzolanic reactions, resulting in improved pore refinement and matrix densification. Specimens with calcined montmorillonite at 600 °C–800 °C showed superior strength and durability performance.Discussion: The combined use of calcined montmorillonite and 15% PCG biochar at 350 °C provides a sustainable approach for improving concrete performance.Item IoT-based demand-side energy management: Enhancing peak hour efficiency through automated control of appliances(PLOS One, 2026-05-04) Tweve, Exaud; Philipo, Godiana; Kichonge, Baraka; Kivevele, ThomasIndustrial solar microgrids experience pronounced peak demand due to aggregated production processes, auxiliary systems, and shift-based operation. Conventional demand response approaches rely on voluntary participation and aggregated energy metrics, which limits their effectiveness in industrial environments. This study presents an IoT-based demand-side energy management framework for industrial microgrids that explicitly distinguishes active power, reactive power, and apparent power during peak operation. The system integrates real-time power factor monitoring, automated reactive power compensation, and prioritized load control using low-latency IoT communication. A high-fidelity simulation model was developed in Proteus 8.15 and validated using a physical IoT prototype calibrated against industrial measurement data. Performance evaluation combined experimental measurements with historical load data from an operating industrial facility. Automatic power factor correction reduced apparent power demand by 41.58% due to reactive power mitigation. Real power decreased by 1.6 and 2.6% for both hardware and simulation respectively. The result shows that power factor correction reduces current and releases inverter capacity. It does not produce large reductions in real energy consumption. Automated shedding of non-critical loads reduced real power demand by 23.46% during peak periods. The non-critical loads include auxiliary lighting and support equipment rated at approximately 0.063 kW. These loads represent 4 percent of the monitored site load. Classification followed production continuity, safety requirements, and operational redundancy. Load factor increased by 23.4%, and both peak demand and peak-to-average ratio decreased by 20% relative to baseline operation. The results demonstrate that automated industrial demand-side energy management improves electrical performance and peak demand characteristics without reliance on voluntary user response. The proposed framework provides a practical foundation for power-quality-aware demand management in industrial solar microgrids.Item High-performance eco-concrete beams with calcined montmorillonite, metakaolin pyrolyzed coffee grounds, and hybrid fibers for enhanced bending strength and microstructural refinement(PLOS One, 2026-03-05) Hepautwa, Amani; Hilonga, Askwar; Mrosso, Register; Alfredy, Tusekile; Mwalusambo, Gabriel; Lesafi, Fina; Chande, YusufuThis study investigates the flexural performance and microstructural evolution of reinforced concrete beams incorporating calcined montmorillonite (CMMT), metakaolin (MK), pyrolyzed coffee grounds (PCG), and hybrid fibers (steel or banana) as sustainable partial replacements for natural sand and cementitious binders. The replacement levels—12.5% SCM (CMMT or MK) and 15% PCG—were selected based on preliminary optimization trials and evidence from prior studies that identify these ranges as the threshold at which pozzolanic reactivity, workability, and particle packing achieve maximum benefit without compromising matrix integrity. Thirteen mix groups and a control beam were cast and tested under four-point bending, with three replicates per group. Statistical analysis using one-way ANOVA (α = 0.05) confirmed significant differences in peak load, stiffness, ductility, and energy absorption across mixes (p < 0.05). Beams containing CMMT and 1.5% steel fibers achieved the highest flexural capacity, exhibiting a 92–105% increase in ultimate load relative to the control, while mixes with 1.0% banana fibers demonstrated the greatest ductility and post-cracking deformation capacity. Improvements in stiffness (up to 68%) and energy absorption (up to 120%) were closely linked to microstructural refinement observed through XRD and SEM. Quantitative indicators—including a 22–34% reduction in portlandite peak intensity, an increase in amorphous C–S–H content, and visibly compacted interfacial transition zones—corroborated the enhanced matrix densification induced by CMMT and PCG.The combined use of PCG, CMMT, and natural/steel fibers significantly reduced reliance on natural sand and cement while improving structural performance, demonstrating a viable pathway for developing high-performance eco-concretes for structural applications. Although direct durability tests were not conducted, the observed microstructural densification suggests potential improvements in long-term resistance to moisture and chloride ingress, warranting further research.Item Fertilizer-derived uranium uptake in maize (Zea mays L.): Findings from pot and field experiments in Tanzania(Elsevier B.V., 2026-04-08) Haneklaus, Nils; Mwalongo, Dennis; Mohammed, Najat; Lisuma, Jacob; Brink, Hendrik; Mupambwa, Hupenyu; Mazouz, Hamid; Chubur, Viktoriia; Roubík, Hynek; Qu, Guangfei; Wacławek, Stanisław; Mtei, KelvinPhosphate fertilizers can introduce uranium (U) into agricultural soils and potentially into edible crop tissues. This work evaluated U transfer from fertilizers into maize (Zea mays L.) under Tanzanian field and pot conditions. Three fertilizers with contrasting intrinsic U concentrations (39–160 mg kg⁻¹) were assessed in a single-season field experiment and in a replicated pot experiment, together with measurements of calcium (Ca) and exploratory bark and kaolin amendment treatments to mitigate U transfer from soil to plant. In the field experiments, interpreted descriptively, U concentrations were highest in soil (2.07–3.96 mg kg⁻¹), intermediate in roots (0.99–2.20 mg kg⁻¹), stems (0.39–1.09 mg kg⁻¹), and leaves (0.17–0.48 mg kg⁻¹), and lowest in grain (0.09–0.26 mg kg⁻¹, ash basis). In the pot experiment, one-way ANOVA showed highly significant treatment effects for U in soil, root, stem, and leaf compartments (all p < 0.001), and fertilizer/amendment interactions were significant among fertilized pots, indicating treatment-specific responses. Transfer coefficients for U and Ca supported a consistent partitioning pattern of soil > root > stem ≈ leaf > grain and showed that U transfer to grain remained strongly attenuated in both systems. Several amendment treatments, particularly kaolin and tree bark sawdust, were associated with reduced U concentrations and reduced transfer beyond the root compartment in the pot experiments, although no mechanistic measurements were made. Overall, the results identified fertilizer sources and compartmental partitioning as key controls on maize U accumulation and provided regionally relevant baseline data for exposure assessment and for future testing of low-cost retention measures under field-relevant conditions.Item Enhanced fixed-bed column adsorption using a ternary MgO-impregnated eggshell–kaolin composite: Toward an efficient and sustainable fluoride removal technology(2026-01-26) Kitemangu, Aisha; Machunda, Revocatus; Rwiza, Mwemezi; Malima, Nyemaga; Banyikwa, Andrew; Mataba, GordianIn this study, a ternary MgO-impregnated eggshell–kaolin (EKM) composite was synthesized and evaluated for fluoride removal from water under fixed-bed column adsorption. The composite, prepared by co-precipitation and wet impregnation, was characterized using XRD, FTIR, SEM EDX, and Brunauer–Emmet–Teller analyses. Results confirmed successful integration of the three components, yielding a mesoporous structure with a surface area of 158.5 m2 g−1. The composite exhibited good defluoridation performance under varying operational conditions. Higher bed depth and lower flow rate enhanced adsorption capacity, achieving up to 6.35 mg g−1 at 10 mg L−1 influent fluoride concentration. Breakthrough data were well described by the Thomas, Clark, and Yoon–Nelson models (R2 ≥ 0.94) at lower influent concentration, moderate flow rate, and greater bed depth, while the bed depth service time model confirmed a linear increase in service time with bed depth. The adsorbent maintained good regeneration ability across four cycles. Co-existing anions showed interference with the uptake of F−, with inhibitory effects following the order: PO3−4>SO2−4>NO−3 > Cl−. The study estimated that 11.11 g of EKM composite yields 2 L of safe water for less than USD1. These results highlight the EKM com posite as an efficient and sustainable adsorbent for practical defluoridation applications.Item Development of persulfate-treated bone char for efficient fluoride adsorption in aqueous media: kinetics, isotherm and thermodynamic studies(Springer Nature, 2026-01-08) Ibrahim, Mohamed; Akinropo, Oyetade; Mouhamadou, Sali; Nikiforov, Anton; Leys, Christophe; Sadou, Dalhatou; Hilonga, AskwarEndemic fluorosis in human skeletal frameworks is caused by drinking water with a high amount of fluoride ions (F−). Addressing the challenge necessitates the development of a high-performance adsorbent for F− removal in aqueous media. Thus, the current study evaluates the performance of BC associated with persulfate (PS) for F− removal for the first time (BC/PS system). The adsorption performance of the BC/PS system was tested at 10 mg/L initial concentration and pH = 7 while varying the contact time (1–5 min). Additionally, a persulfate-treated BC (BC-PS) was prepared and tested for F− adsorption. The modified adsorbent (BC-PS) was characterized to evaluate the morphology, surface area, surface functional groups and chemical composition materials. The BC/PS system showed significantly higher F⁻ removal efficiency (52.1% to 86.63%) compared to BC alone (22.23% to 42.93%) under 1 and 5 min contact time. The observed effect was mainly attributed to the acidification properties of BC/PS system due to the release of H+ during the adsorption process. Also, BC-PS adsorbent exhibited almost twice the sorption capacity (15.981 mg/g) as compared to 9.037 mg/g of BC for F− removal. The isotherm model reveals that the process follows Langmuir isotherm (R2 = 0.999) with process kinetics defined by a pseudo-second-order model (R2 = 0.996). Thermodynamic analysis of F− adsorption on BC-PS indicates an endothermic physisorption (∆H° = 1.70 kJ/mol) and non- spontaneous (∆G° ˃ 0) process. Overall, the study revealed that PS treatment of BC can enhance the adsorption efficiency of the absorbent, making it a sustainable sorbent alternative.Item Cyclical sustainability in practice: how tourists emotionally legitimate third-sector tourism in Tanzania(Taylor & Fransic Online, 2026-04-15) Kimaro, Joseph; Ibrahim, Shahnaz; Karatas-Ozkan, Mine; Kimaro, Julius; Rwiza, MwemeziThis study draws on a netnographic analysis of 357 TripAdvisor reviews and 15 semi-structured interviews with staff, managers, and beneficiaries to examine how tourists perceive third-sector tourism organisations in northern Tanzania. Sustainable tourism is increasingly mediated by tourists' affective engagement with community-rooted initiatives. Anchored in the doughnut economy framework, the findings show that tourists view these organisations as ethical spaces promoting ecological care, inclusion, and social cohesion. Tourists experience pride, empowerment, and moral fulfilment, cultivating pro-sustainability behaviours. We conceptualise this process as cyclical sustainability: a reciprocal co-creation of value between tourists and third-sector actors. The study offers actionable insights for policymakers and destination planners, advocating for the strategic integration of third-sector organisations as pivotal stakeholders in fostering culturally embedded, emotionally resonant, and sustainability-aligned tourism ecosystems.Item Epidemiological and entomological analysis of imported malaria in Pemba Island, Zanzibar: a study from 2020–2022(Springer Nature, 2025-12-04) Ali, Ali; Ali, Ali M.; Mwema, Mwema; Mlacha, YerominBackground Since 2008, Zanzibar has significantly reduced the prevalence of malaria, keeping it at 1%. However, imported malaria particularly from mainland Tanzania continues to pose a major threat to sustaining these gains, especially on Pemba Island where 67.8% of cases in 2021 were classified as imported. This study analysed malaria cases reported from 2020 to 2022, focusing on epidemiological and spatial trends of imported infections to inform more effective surveillance and response. Methods Retrospective analysis of malaria surveillance data from 2020 to 2022 was conducted to characterize the epidemiological parameters focusing on spatial and temporal patterns of imported malaria cases and their origin. Entomological data obtained from routine surveillance at four sentinel sites used to assess the receptivity of these areas to malaria transmission. Geographical location, season, sex and malaria intensity in the travel destination regions were evaluated in relation to the trend of malaria importation using a negative binomial regression model. The odds of importation were assessed using both univariate and multivariate regression models. Results Between 2020 and 2022, 2646 malaria cases were reported in Pemba, of which 1411 (53.3%) were classi fied as imported. Imported cases were significantly higher among males (57.3%, p < 0.0001) and adults over 18 years (68%, p < 0.0001). Tanga (61%), Dar es Salaam (12%), and the Coastal Region (10%) accounted for the major ity of cases (98%) that came from mainland Tanzania. Only 2% of cases were traced to three neighbouring countries. Importation rates were significantly lower in Micheweni(IRR = 0.48, p = 0.001) than in Wete dis trict, and higher in Mkoani (IRR = 2.45, p < 0.001). Lower number of imported cases was observed during the rainy season (IRR = 0.83, p = 0.049) and among travellers returning from regions with low or moderate transmission. The odds of malaria importation were found to be significantly higher in 2021 (OR = 3.58, p < 0.001) and 2022 (OR = 5.62, p < 0.001) relative to 2020. No significant correlation was identified between case distribution and Anopheles bit ing density (r = 0.12, p = 0.5). However, a significant association was found between Human Biting Rate (HBR) and imported cases, with each unit increase in HBR predicting an 84.81-unit increase in the log-transformed number of imported cases (95% CI 13.29–156.32, p = 0.021). Mkoani district was identified as the most receptive area. Conclusion Imported cases has been confirmed as a persistent barrier to elimination in Pemba. These findings underscore the need for enhanced cross-border surveillance, spatially targeted interventions, and the integration of entomological and epidemiological data to inform malaria elimination strategies.Item Sublethal Pyriproxyfen Exposure Alters Anopheles arabiensis Fitness and Pyrethroid Susceptibility Without Trans-Generational Carry-Over(MDPI, 2026-02-02) Mnzava, Simoni; Mmbaga, Augustino; Mutashobya, Anitha; Muyaga, Letus; Mwema, Mwema; Ngowo, Halfan; Lwetoijera, DicksonBackground: Pyriproxyfen (PPF), a juvenile hormone analog, is a promising chemical for autodissemination strategies, where mosquitoes aid in transferring insecticides to their breeding sites. This study evaluated the effects of sublethal PPF doses on Anopheles arabiensis fitness (fecundity, fertility, and body size) and pyrethroids susceptibility across three generations. Methods: Laboratory-reared, pyrethroid-resistant mosquito larvae were exposed once to sublethal PPF concentrations of (0.0003, 0.0006, 0.0008, and 0.001 mg a.i./L), which caused emergence inhibition rates of 5%, 10%, 15%, and 20%, respectively, alongside a control group. Emerged adults were tested for susceptibility to 0.75% permethrin, 3.75% permethrin, and 0.05% deltamethrin using WHO tube bioassays. Knockdown was recorded at 1 h, mortality at 24 h post-exposure, while fecundity, fertility, and body size were measured across three generations. Results: First-generation Anopheles arabiensis emerging from PPF-treated larvae showed reduced susceptibility to 0.75% permethrin and 0.05% deltamethrin compared to controls. Mortality from permethrin dropped from 22.7% in the controls to 11% and then 3% at 0.0003 and 0.001 mg a.i./L. For deltamethrin, mortality fell from 62.7% to 36% and then 23.3% at the same concentrations. Knockdown at 60 min was also significantly reduced, with permethrin KDT60 dropping from 41.3% in controls to 9.3% and 3.3%, and deltamethrin KDT60 from 79.7% to 66.7% and 65%. No significant differences were observed in subsequent generations (p > 0.05). PPF exposure also induced notable fitness costs in the first generation: mean wing length decreased from 3.07 mm in controls to 2.88–2.66 mm (6–13% reduction), mean egg production dropped from 30.1 to 13.9–18.8 eggs per female (37–54% reduction), and egg hatching rate declined from 87% to 79–82% (6–9% reduction). Conclusions: These findings suggest that sublethal PPF doses can temporarily enhance insecticide resistance without leading to heritable resistance and negatively impact key mosquito fitness traits. PPF may thus be a valuable addition to integrated vector management strategies.Item Valorisation of cattail (Typha) biomass: Fibre extraction, properties, and applications in sustainable material systems(Elsevier Ltd., 2026-01-18) Tarus, Bethwel; Alfredy, Tusekile; Mwasiagi, Josphat; Jande, YusufuThe cattail plant (Typha spp.) is a low-cost, renewable, and multifunctional natural fibre resource with strong potential for sustainable and circular material systems. This review explores the extraction methods, properties, and application potential of cattail fibres. Fibre origin and the extraction route are key factors affecting fibre microstructure and performance. Mechanical extraction typically yields fibres with high variability, whereas optimized alkali, enzymatic, and hybrid treatments substantially enhance fibre quality. Consequently, reported tensile strengths for leaf and stem fibres span from below 100 MPa in untreated form to values exceeding 1000 MPa under optimized processing conditions. On a specific property basis, optimized cattail leaf/stem fibres perform competitively compared to conventional fibres, albeit with greater variability. In composites, cattail f ibres act as effective lightweight reinforcements, offering improved mechanical performance, energy absorption, and damping. Cattail seed fibres, despite limited tensile capacity, exhibit exceptional bulk resilience and hy drophobicity, enabling insulation, cushioning, filtration, and oil-sorption applications. Overall, cattail fibres emerge as versatile materials whose performance is governed by method-property relationships, supporting their potential as next-generation sustainable materials.Item Compressed natural gas in aged internal combustion engines: performance, emissions, and challenges – a systematic review(Elsevier Ltd., 2026-03-06) Kyando, Michael; Ntalikwa, Justin; Kivevele, ThomasCompressed natural gas (CNG) offers significant emissions advantages over gasoline and diesel, yet most literature focuses on new or laboratory-optimized engines rather than the aged, retrofitted vehicles common in developing countries. With addition of other studies, the review followed PRISMA 2020 guidelines and a prospectively registered protocol (OSF) − https://osf.io/c8u7f/. Searches across Scopus, IEEE Xplore, and Google Scholar identified 816 records, of which 26 studies met inclusion criteria. CNG consistently lowered CO, HC, PM, and CO2 emissions, but retrofitted SI engines experienced 10–20% losses in power and torque due to methane’s low volumetric energy density and age-related declines in efficiency. High-mileage fleets showed methane-slip increases, catalyst deterioration, and lubricant oxidation, whereas optimized or dedicated CNG engines demonstrated improved thermal efficiency and fuel economy. Retrofit quality and calibration accuracy proved decisive in determining real-world outcomes. The findings highlight that CNG’s environmental and efficiency benefits are achievable but depend on proper engine design, maintenance, and regulatory support, especially in regions dominated by older vehicle fleets. This review provides the first systematic synthesis focused on aged, high-mileage, and retrofitted spark ignition (SI) and compression ignition (CI) engines operating on CNG, integrating evidence on performance, emissions, combustion behavior, methane slip, lubricant degradation, and catalyst aging. By comparing retrofitted and dedicated CNG engines against real-world aged engine across diverse regions, it reveals how engine architecture, retrofit quality, and accumulated mileage shape CNG outcomes and identifies the operational challenges and research priorities needed for durable, efficient, and low-emission operation.Item Enhancing hydrolysis from cow dung manure using ultraviolet-lamps for efficient biogas production(Journal of Ecological Engineering, 2026-02-01) Kessy, Monica; Hilonga, Askwar; Mohamed, Mohamed; Amasi, AloyceAnaerobic digestion (AD) of livestock waste is a sustainable pathway for renewable energy production, yet methane yield is often limited by the slow hydrolysis of lignocellulosic material. Pretreatment methods have been proposed, but many are costly or environmentally burdensome. This study investigates ultraviolet light irradiation as a novel, low-energy pretreatment to enhance methane production from cow dung. Fresh cow dung was exposed to UV light at 254 nm and intensity and for 0 (control), 30, 60, 90, 120, 150, and 180 minutes before undergoing 35-day anaerobic digestion at 37 °C. Methane yield and chemical oxygen demand (COD) removal were monitored. Results revealed a significant effect of UV exposure duration on both methane yield (p < 0.05) and COD removal (p < 0.05). Optimal performance occurred at 120 minutes (methane yield: 126 ± 28.3 mL/day; COD removal: 58.9%), representing a more than twofold improvement compared to the control. Overexposure (≥150 minutes) decreased methane yield and COD removal, likely due to the generation of inhibitory by-products. These findings suggest that UV light pretreatment, when optimised, can partially overcome hydrolysis limitations in AD. However, the study did not assess microbial dynamics, chemical intermediates, or scale-up feasibility, which remain critical gaps for future research.Item Assessment of liquid radioactive waste characteristics and management practices in nuclear medicine facilities in Tanzania(Journal of Ecological Engineering, 2026) Kamaze, Didat; Jande, Yusufu; Amasi, Aloyce ; Mwaijengo, GriteResidual liquids waste generated during nuclear medicine procedures may contain radioactive materials and toxic chemicals that pose potential risks to the environment and public health. This study assessed the physicochemical properties, radionuclide activity, heavy metal concentrations and Management practices of liquid radioactive waste generated at two major nuclear medicine facilities in Tanzania: Ocean Road Cancer Institute (ORCI) and Bugando Medical Centre (BMC). A cross-sectional study was conducted over eight days at ORCI and ten days at BMC. Approximately 735 mL of liquid waste was collected at each facility and combined into three composite samples per site. Radiation levels, physicochemical parameters, and heavy metal concentrations were measured using the APHA Standard Methods for the Examination of Water and Wastewater. Heavy metal contamination was evaluated using the Contamination Factor, Degree of Contamination, Pollution Load Index, Heavy Metal Pollution Index, and Metal Index. Results were compared against World Health Organization (WHO) guideline limits.Statistical differences between facilities were assessed using the Mann-Whitney U test, while radionuclide decay was modeled using exponential regression to estimate half-lives. The results indicated rapid radionuclide decay, with estimated half-lives of 0.62, 0.83, and 0.96 days for Tc-99m and Ga-68. Ambient radiation levels ranged from 0.15-0.75 µSv/h at ORCI and 0.38-0.85 µSv/h at BMC, with eleveted readings observed in generator storage areas, hot laboratories, and gamma camera rooms. No significant differences in radiation levels were observed between the two facilities (W = 11, p = 0.296). ORCI effluents were acidic (pH 3.84 ± 0.67) with higher conductivity and TDS, while BMC effluents were near neutral (pH 7.09 ± 0.21) and exibted higher salinity and turbidity.Concentrations of Cd , Ni , and Pb exceeded WHO limits at both sites, while Zn concentrations ware significantly higher at BMC (5.98 ± 0.072 mg/L) compared to ORCI (0.87 ± 0.012 mg/L, p < 0.001). In conclusion, radiological risks associated with liquid waste from nuclear medicine facilities appear to be adequetely controlled; however, chemical and heavy metal contamination remains a notable environmental concern. Radiological risks associated with liquid waste from routine monitoring, wastewater treatment practices, and strengthened regulatory oversight measures are recommended to mitigate these hazards.Item Techno-economic analysis of biohydrogen production from lignocelluloses biomass via co-pyrolysis and gasification process(Springer Nature, 2026-03-05) Kichonge, Baraka; Monge, Emmanuel; Kaborogo, FulmenceHydrogen production from renewable biomass offers a pathway toward low-carbon energy systems. This study presents a techno-economic assessment of hydrogen generation from lignocellulosic biomass through an integrated pyrolysis, gasification, and reforming process modeled in Aspen Plus V10. The process design applies the Peng-Robinson equation of state for thermodynamic predictions and integrates methane steam reforming and water gas shift reactions to enhance hydrogen yield. Simulation results show a hydrogen yield of 0.0742 kg H₂ per kg biomass with a purity of 99.91%, representing a 40.5% improvement over standalone gasification. Pinch analysis demonstrates a 20% reduction in energy consumption through heat recovery. Economic evaluation estimates a capital cost of USD 14.8 million and an operating cost of USD 5.9 million per year, yielding a payback period of 5.52 years, an internal rate of return of 39.16%, and a net present value of USD 166.31 million. Integration of CO₂ capture reduces emissions by approximately 50% compared to conventional steam methane reforming. These results confirm the technical and economic feasibility of the process and its relevance for sustainable hydrogen production.Item Sisal fiber degradation treatment by different methods for cement composite materials(Springer Nature, 2026-02-15) Fode, Tsion; Jande, Yusufu; Kivevele, Thomas; Rahbar, NimaSisal fiber is the most extensively cultivated and strong natural fiber extracted from the Agave-sisalana plant leaf. The use of sisal fiber in concrete or mortar has a lot of benefits, however it degrade due to mineralization from cementitious materials and moisture absorption. Numerous studies have explored surface treatment methods to reduce this deterioration, however the combined effects of different treatment approaches on the performance of sisal fiber in cement composites remain not well known. This study addresses this gap by systematically evaluating the influence of calcined bentonite, varying concentrations of alkaline solutions by 5% and 10% NaOH, additionally, using 150 °C and 200 °C thermal treatments on reducing the degradation of sisal fiber in cement-based materials. The findings reveal that all three treatments—thermal, alkaline, and calcined bentonite—were effective in removing lignin and surface impurities from the fibers. Notably, fibers treated with 5% sodium hydroxide, heated to 150 °C, or treated with calcined bentonite exhibited improved durability after 10 wetting and drying cycles, showing increases in breaking load resistance of 28.95%, 32.11%, and 33.37%, respectively. These treatments also significantly reduced water absorption by 34.89%, 29.27%, and 60.95%, compared to untreated fibers. Moreover, the calcined bentonite-treated fiber showed reduced mass loss by 28.18% at 367 °C and 29.08% at 600 °C when compared to raw sisal fiber. Incorporating the treated fibers into mortar mixtures resulted in reduced fresh density and enhancements in both compressive and flexural strength. Specifically, fibers treated at 150 °C and with calcined bentonite improved the 28 days compressive strength by 23.31% and 23.44%, respectively, compared to mortar with untreated fibers.Item Photovoltaic system performance in Sub Saharan Africa under environmental, technical and policy constraints(Springer Nature, 2026-02-01) Kichonge, Baraka; Mwakapoma, SamsonPhotovoltaic systems in Sub-Saharan Africa (SSA) face efficiency losses from three key factors: high operating temperatures, dust accumulation, and inconsistent policies. Field data confirm crystalline silicon modules lose substantial efficiency (15–20% range) at elevated temperatures, while dust reduces output by approximately half in worst-case scenarios. Passive cooling methods demonstrate measurable performance recovery, with active systems achieving greater improvements at higher resource costs. Recent observations reveal maintenance challenges, particularly in tropical zones where protective coatings degrade faster than manufacturer estimates. The analysis identifies recurring barriers, including fragmented financing and mismatched cleaning schedules relative to dust exposure. Hybrid cooling configurations combining passive and limited active components show promise for balancing cost and performance. Three actionable priorities emerge: (1) adapted component specifications for high-temperature operation, (2) revised maintenance protocols for regional dust conditions, and (3) standardized certification for tropical-grade PV systems. Implementation roadmaps account for climate variations across arid, tropical, and coastal zones. The review provides both technical benchmarks and policy frameworks to address performance gaps specific to SSA conditions.Item Life cycle and techno-economic assessment of a solar-biogas hybrid dryer for banana drying(PLOS One, 2026-01-23) Shigella, Oscar; Loemba, Aldé; Yawe, John; Kichonge, Baraka; Mwema, MwemaThis study evaluates the environmental impact and economic viability of a solar- biogas hybrid dryer using life cycle assessment (LCA) and techno-economic analysis. The LCA, in accordance with ISO 14040/14044, employs a cradle-to-grave approach using the ReCiPe 2016 Midpoint method. Results indicate a global warming poten tial of 1,100 kg CO₂-eq per functional unit, primarily from mild steel (69.4%) and aluminium (18.8%), representing 40–50% lower emissions than solar-electric and solar-diesel hybrid systems. Total energy consumption is 9,110 MJ per functional unit, with fossil fuels dominating (82.4%), while renewable energy use remains minimal. Human toxicity is significant, with mild steel and aluminium contributing 71.6% and 13.2% to carcinogenic toxicity, respectively. Integrating biogas reduces dependence on grid electricity and lowers operational emissions by 85%. Techno-economic analy sis shows capital expenditure (CapEx) of USD 3,618.20 and operational expenditure (OpEx) of USD 9,458, with a payback period of 1.3 years and return on investment of 76.39%, indicating strong economic viability. Sensitivity analysis reveals that reduc tions in banana prices decrease operating expenses and the payback period, while reductions in biogas costs increase net cash flow and return on investment. The dryer demonstrates lower global warming potential and energy use compared with conventional dryers, supporting its adoption for sustainable agricultural processing in sub-Saharan Africa.Item Integrating ageing into minimum energy performance standards (MEPS) for sustainable and efficient refrigeration in East Africa(IOPPublishing Ltd, 2026-01-21) Kakande, Josephine; Philipo, Godiana; Krauter, StefanThe biggest growth in residential electricity consumption across Africa is projected to arise from the increased proliferation of cooling devices such as air conditioners, fans, and refrigeration units. This growth is due to rising urbanisation, economic development, electrification expansion and climate change effects. This study investigates the performance of four domestic freezers at a residential site in Kenya, focusing on efficiency degradation evaluation and its implications for long-term energy consumption. Based on appliance temperature evolution measurements, the Bonn method is discussed as a means of evaluating energy efficiency decline over time due to insulation degradation. An ageing model for refrigeration appliances that predicts energy consumption increase of 23% over a 10 year lifetime and 28% over a 20 year lifetime is discussed, highlighting the need for efficiency standards and policies that account for appliance ageing. To address this gap, revised minimum energy performance standards for East Africa that incorporate an ageing factor are presented. It is envisaged that integrating ageing provisions, which should be done globally, will promote efficiency in refrigeration, thereby mitigating electricity demand growth, enhancing energy system reliability, and supporting sustainable cooling.