Research Articles [MEWES]

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Social determinants for household clean water accessibility in northern Tanzania: A case of Kikwe peri-urban ward in Arusha
(African Quarterly Social Science Review, 2025) Ngayaga, Mwahija; Nade, Paschal; Mpumi, Nelson; Ripanda, Asha; Rwiza, Mwemezi
Clean water accessibility is vital to human health and well-being, a fundamental human right. Over 1.7 billion people do not have consistent access to safe drinking water, negatively affecting their health and socioeconomic status. Despite global recognition of clean water as a fundamental human right, many households in peri-urban areas of developing countries, including northern Tanzania, continue to face significant challenges in accessing reliable water sources. In the Kikwe peri-urban ward, disparities in access to clean water are influenced by various social determinants such as education level, gender roles, marital status, and proximity to water sources. These social factors contribute to unequal water distribution and increased vulnerability to waterborne diseases and economic burdens, especially among women and marginalized groups. However, limited empirical data exists on how these social determinants specifically affect household water access in Kikwe, hindering the development of targeted, evidence-based interventions. This study, therefore, aimed to investigate the social determinants of household clean water accessibility in Kikwe peri-urban ward of northern Tanzania. The cross-sectional survey combined quantitative and qualitative research methods on 353 respondents sampled from the Kikwe ward. Inference and descriptive statistics were employed to analyze the social determinants and respective associations with clean water accessibility. Results show that 64% of respondents finished elementary school, 53% were male, the majority 25.8% aged between 45 to 54, 73.7% were married, 37.4% rely on water from the rivers, 33.7% use public standpipes as the primary source of water, 62.9% female primarily responsible for fetching water and 84.7% of users do not treat water for their daily use. A weak significant correlation existed between water sources and social variables tested, implying clean water is an essential commodity, which needs to be distributed equally regardless of individual status. The findings highlight that clean water accessibility in peri-urban Kikwe is significantly influenced by social inequalities, particularly gender, and proximity to water sources. While the statistical correlations were weak, the trends point to systemic disparities that require deliberate policy attention. It is concluded that equitable access to clean water cannot be achieved without addressing these underlying social determinants. Therefore, it is recommended that targeted educational programs using mobile platforms be introduced to enhance awareness on water treatment and conservation. Additionally, empowering communities through participatory water governance, investing in affordable and decentralized water treatment solutions, and improving local infrastructure is critical for long-term water security and public health resilience in peri-urban areas like Kikwe.
Performance comparison of temperature-based and mass transfer-based horizontal subsurface flow constructed wetland designs
(IWA Publishing, 2025-06-20) Rugaika, Anita; Bruggen, Bart; Njau, Karoli
Two similar horizontal subsurface flow constructed wetlands (HSSF-CWs) that only differ in the wastewater flow length were compared in terms of their performances. The HSSF-CW with a longer wastewater flow length has two baffles, implying that interstitial velocity was considered when designing the system. In contrast, the unbaffled HSSF-CW considered temperature when designing. A significant difference (P < 0.05) was observed between the two systems in the removal of biological oxygen demand (BOD), chemical oxygen demand (COD), ammonia nitrogen, and fecal coliform (FC). Baffled system effluent contained mean BOD levels (32 ± 13 mgO2/L), COD (47 ± 15 mgO2/L), ammonia nitrogen (28 ± 8 mgN/L), and FC (4.4 ± 0.2 log unit). Unbaffled system effluent contained mean BOD levels (38 ± 16 mg/L), COD (57 ± 20 mg/L), ammonia nitrogen (31 ± 8 mgN/L), and FC (5 ± 0.2 log unit). No significant difference (P > 0.05) between the two systems was observed for nitrate nitrogen and phosphorus reduction. In general, the performance of the baffled system was better than the unbaffled one, although both systems complied with the WHO discharge limit for the COD (60 mgO2/L). This confirms that the interstitial velocity is an important parameter in HSSF-CW designing in tropical countries.
Institutional Frameworks and Household Clean Water Accessibility in Peri-Urban Communities of Northern Tanzania: A Case of the Suburban Ward
(African Quarterly Social Science Review, 2025-05-13) Ngayaga, Mwahija; Nade, Paschal; Rwiza, Mwemezi; Ripanda, Asha
The lack of clean water contributes to the transmission of waterborne diseases such as cholera, dysentery, and typhoid, particularly among vulnerable populations. This situation threatens public health, especially in resource-limited settings. Various regulatory and environmental factors, including bylaws and policies, water tariffs, electricity access, flooding, infrastructure conditions, pollution, and drought, significantly impact access to clean water by influencing the availability and quality of water resources. This study examines the regulatory environment factors affecting access to clean water in peri-urban communities reliant on piped systems, focusing on household clean water availability in northern Tanzania. Based on the Mary Douglas's Cultural Theory, the study adopted a cross-sectional design to collect quantitative data. Questionnaires were administered to a purposive sample of 353 respondents drawn from a target population of 10,965 individuals from 3,030 households, all aged 18 years or older. Data analysis was conducted using descriptive statistics with the aid of SPSS software. Qualitative data was collected from key informants through interviews and analysed thematically. The results revealed that 51% were aware of the water and environmental policies, 84.7% participated in meetings, 23.2% paid water bills, and access to clean water throughout the year was challenging. The chi-square test indicated a significant relationship (χ² = 48.118, df = 12, p = 0.000) between institutional frameworks and clean water accessibility. Additionally, planting trees and properly managing water sources contribute to the protection of water resources. Educating the community and protecting water sources play a significant role in preserving ecological health and ensuring the sustainability of communities. The study concludes that there is a relationship between regulatory frameworks and clean water accessibility in northern Tanzania. The study recommends continuous provision of education and awareness programs focused on the effective use, management, and protection of water sources to ensure public health and clean water accessible sustainability.
Assessing the Performance of Constructed Wetland for Acid Mine Drainage Treatment Using Sugarcane Molasses as a Carbon Source
(Scientific Research Publishing, 2025-04-22) Buddy, Zainabu; Njau, Oscar; Rugaika, Anita; Njau, Karoli
Acid mine drainage (AMD) is a widespread environmental issue at mining sites globally. AMD is caused by pyrite oxidation which produces an acidic discharge > 2500 mg/L of sulfate, dissolved heavy metals at high amounts and low pH (2 - 4.5). AMD has serious health impact on living organisms. The present study aimed to assess the performance of locally available, high-organic matter containing by-products, specifically sugarcane molasses (SCM), as a carbon source for AMD treatment. In batch experiments containing SCM and control, 99% sulfate and nitrate reductions were reached. Heavy metal removal efficiencies > 94% were achieved for Cu, Fe, Mn, and Zn, in the SCM inoculated columns, while efficiencies > 42% were recorded in the control columns. The column experiments removed 99% of the initial Al concentrations but were not very effective in COD reduction to acceptable limits. The findings reported by this study verify that high carbon containing substrates can be used to remediate metal and sulfate contaminated water in mining areas.
Capacitive deionization for water desalination using Na3Fe2(PO4)3/activated carbon composite electrodes
(Elsevier, 2025-05-28) Sufiani, Omari; Alfredy, Tusekile; Tanaka, Hideki; Teshima, Katsuya; Machunda, Revocatus; Jande, Yusufu
Water desalination technologies are attracting growing global attention as critical solutions to address water scarcity torturing mankind worldwide. Capacitive deionization (CDI) is an emerging desalination technology that offers multiple advantages, including low voltage operation and diverse material options for electrode synthesis. In this work the Na3Fe2(PO4)3 (NFP) is composited with the activated carbon (AC) to synthesize AC/NFP composites and tested in water desalination. The characterization results from several techniques reveal the successful composite synthesis. When tested in CDI experiments for brackish water desalination much higher salt removal capacity of around 22.0 was attained by AC/NFP 1:2 compared with 18.65 mg/g of AC electrode. Also, the synthesized AC/NFP 1:2 retain satisfactorily performance efficiency when cycled for twenty runs. However, owing to low resistance at the electrode-electrolyte interface the AC is more energy efficient as it exhibits much low energy consumption of about 0.056 kWh/m3 compared with the AC/NFP 1:2 cell attained 0.15 kWh/m3. This study reveals a trade-off between performance and efficiency: while the AC/NFP 1:2 cell exhibits higher salt removal capacity, it consumes significantly more energy than the AC electrode, which demonstrate superior energy efficiency.
Effect of Electron Donor Groups on Optoelectronic Properties of Betalain Dyes: A DFT Study
(wiley, 2025-05) Tsere, Melkizedeck; Costa, Rene; Deogratias, Geradius; Pogrebnaya, Tatiana; Pogrebnoi, Alexander; Machunda, Revocatus; Al-Qurashi, Ohoud; Wazzan, Nuha; Babu, Nambury
A sensitizer is a vital component of dye-sensitized solar cells(DSSCs); it absorbs incident photons, excites electrons, and facil-itates charge transfer to the semiconductor. In the present work,modification of betalain dyes through grafting of electron donorgroups has been performed. The reported optoelectronic properties of the investigated dyes are determined using densityfunctional theory (DFT) and time-dependent DFT methods. The investigated sensitizers exhibit maximum absorption between400 and 442 nm with light-harvesting efficiencies exceeding 93%.Favorable interactions are observed between the dyes and the hydrogenated TiO2 cluster, (TiO2)6H3. The obtained binding energies range from 1.39 to 0.97 eV in the gas phase and 0.31 to 0.03 eV in water. The electronic spectra of the dye@TiO2 complexes show broader and intensive bands with bathochromicshifts when compared to the individual dyes. The charge density distribution in the complexes indicates appropriate ability of thedyes for charge injection to the semiconductor. Among the considered dyes, the most promising candidates for use in DSSCs have been selected.
Jamun Seed (Syzygium Cumini) Biochar as a Potential Adsorbent for Environmental Applications
(Engineered Science Publisher, 2025-02-18) Ripanda, Asha; Rwiza, Mwemezi; Giridhar Reddy, S.; Nyanza, Elias; Bakari, Ramadhani; Miraji, Hossein; Ravikumar, C. R.; Ananda Murthy, H. C.; Vuai, Saidi; Machunda, Revocatus; Annamareddy, Sri Hari
This study investigates the properties and adsorption performance of jamun seed biochar (JS biochar) produced through calcination at varying temperatures. Elemental analysis reveals that the carbon content significantly increases from 64.25 to 87.93 wt.% as calcination temperature rises from 400 to 600 °C, while nitrogen content remains within the range of 2 to 2.29 wt.%. The biochar's surface characteristics, with a maximum specific surface area of 261.2 m²/g, demonstrate strong adsorption capacity for small organic molecules, including ciprofloxacin (555.55 mg/g) and lamivudine (400 mg/g). The identified functional groups, including hydroxyl and carbonyl groups, enhance adsorption through mechanisms such as hydrogen bonding and electrostatic interactions. The observed porous, rough surface morphology supports the material's effectiveness as an adsorbent. The results demonstrate JS biochar’s high adsorption capacity, governed by a synergistic interplay of physisorption and chemisorption. This research underscores the potential of JS biochar as a sustainable and effective solution for environmental remediation, particularly in mitigating aqueous pollutants. The findings offer valuable insights for optimizing biochar properties to improve adsorption efficiency, thereby promoting sustainable waste management and environmental remediation.
Economic Factors Influencing Household Access to Clean Water in a Peri-Urban Area of Northern Tanzania
(Scientific Research Publishing Inc., 2025-04-30) Ngayaga, Mwahija; Ripanda, Asha; Nade, Paschal; Rwiza, Mwemezi
Economic factors and associated correlations play a crucial role in shaping household access to clean water in peri-urban areas, directly impacting the well-being and health of communities. Most communities globally still lack ac cess to safe and clean water, resulting to illness and even death due to water borne diseases. This study aims to investigate how economic factors influence household access to clean water in a Peri-Urban area of Northern Tanzania. To achieve the objectives of this study, 353 questionnaires were administered, and for qualitative data collection semi-structured interviews were conducted with the key informants. Descriptive and inferential statistics were employed for quantitative data, and qualitative data were thematically analysed. Results show that 70.8% had no piped water, 65.4% were farmers, and 70.5% of individuals earning less than 110,000 TZS were 1.625 times more likely to lack access to clean water than higher-income households (95% CI: 1.221 - 2.163, p = 0.001) and 48.4% depended on water for production. Most communities in Peri-Ur ban area of Northern Tanzania rely on alternative sources of water, including rivers. To achieve sustainable development goal focusing on improvements in water access, policymakers must prioritise economic development initiatives that foster job creation and infrastructure enhancement.
Radioactivity distribution in soil, rock and tailings at the Geita Gold Mine in Tanzania
(Elsevier B. V., 2025-04-30) Mwimanzi, Jerome; Haneklausa, Nils; Bituhe, Tomislav; Brinkf, Hendrik; Kiegielg, Katarzyna; Lolilah, Farida; Marwaa, Janeth; Rwiza, Mwemezi; Mtei, Kelvin
This study evaluated the activity concentrations of natural radionuclides in soil, waste rocks and tailings from the Geita gold mining site in Tanzania using high-resolution gamma spectroscopy. A total of 41 samples: 31 soil, 5 waste rock, and 5 tailing samples were collected around the mine to assess their radiological hazards. The average activity concentrations in soil were 54, 45 and 279 Bq kg-1 for 226Ra, 232Th and 40K. In contrast, tailings exhibited higher activity concentrations of 70, 36 Bq kg-1 for 226Ra and 232Th, and significantly elevated levels of 877 Bq kg-1 for 40K, while waste rocks showed intermediate values, with 66, 73 and 660 Bq kg-1 for 226Ra, 232Th and 40K respectively. Radiological hazard indices were calculated to quantify potential risks. In soil, the radium equivalent activity (Raeq) averaged 139 Bq kg-1, the annual effective dose equivalent (AEDE) was 78 μSv y-1, the annual gonadal dose equivalent (AGDE) reached 430 μSv y-1, and the excess lifetime cancer risk (ELCR) was 0.27 ×10-1. Tailings showed a Raeq of 189 Bq kg-1, AEDE of 111 μSv y-1, AGDE of 678 μSv y-1, and ELCR of 0.39 ×10- 1, while waste rocks exhibited a Raeq of 200 Bq kg-1, AEDE of 108 μSv y-1, AGDE of 642 μSv y-1, and ELCR of 0.37 ×10-3. Notably, the ELCR values for tailings and waste rocks exceeded the global average of 0.29 ×10-3, rendering them unsuitable for use as building materials. The absorbed dose rates were 69 nGy h-1 for soil, 91 nGy h-1 for tailings, and 88 nGy h-1 for waste rocks. One-way ANOVA revealed significant differences (p <0.05) among the matrices. These findings underscore the need for targeted waste management and remediation strategies to mitigate radiological health risks in the investigated mining area as well as other areas with similar characteristics.
Efficiency of honey–grape blend in reducing radiation-induced mucositis in locally advanced head and neck squamous cell carcinoma
(AIMS Press, 2025-03-12) Kyomo, Magaisha; Mpumi, Nelson; Sauli, Elingarami; Lidenge, Salum
This study assessed the efficacy of a honey–grape blend in reducing the severity and onset of radiation oral mucositis (ROM) in patients with locally advanced squamous cell carcinoma of the head and neck. Oral mucositis is an acute side effect caused by chemotherapy or radiotherapy in the head and neck region. ROM affects patients’ quality of life and treatment expenses. Various pharmaceutical and natural remedies, such as sucralfate, aloe vera, and amifostine are used to mitigate the effects of ROM. However, the available modalities’ efficacy is low and is associated with many side effects. Materials and methods: This cohort study was conducted at the Ocean Road Cancer Institute and Besta Polyclinic in Tanzania. The study included 73 patients with locally advanced squamous cell carcinoma of the head and neck treated from March 2024 to August 2024. The World Health Organization mucositis grading system was used to assess patients’ progress weekly. Data analysis was conducted using Statistical Package for Social Science (SPSS) version 27. Results: Delayed onset (15% Grade 3 for the honey–grape group and 45% Grade 3 for the control group at 28 days) and reduced the severity of ROM (only 20% Grade 3 with no Grade 4 for the honey–grape group while for the control group, it was 25% Grade 3 and 20% Grade 4 at 45 days) (p-value < 0.001). Body weight changes at starting and after completion of radiotherapy were observed (2.65 kg average weight loss for the control group and 1.8 kg, 0.45 kg weight gain for the honey group and honey–grape blend group). Prevalence between genders was 62% males and 38% females. Conclusions: Honey and honey 91 blended with grapes can minimize the severity and delay the onset of ROM in patients with locally advanced head and neck cancer. More studies are needed, since no study has been conducted addressing the efficacy of honey–grape blends in reducing ROM severity.
Kinetics and energetics of biodiesel oxidation stability: The impact of Uapaca kirkiana-derived natural antioxidants
(John Wiley & Sons, Ltd., 2025-03) Kahimbi, Henry; Kichonge, Baraka; Kivevele, Thomas
Despite considerable progress in understanding biodiesel autoxidation inhibition, the kinetics and energetics of the inhibition reactions involving natural antioxidants remain underexplored. Most existing research on natural antioxidants has focused on enhancing oxidation stability and other fuel properties. This study aimed to investigate the oxidative stability of croton biodiesel (CBD) and assess the kinetics and energetics of natural antioxidants derived from the roots, pulp, and fruit peels of the Uapaca kirkiana plant. The oxidation stability of biodiesel samples was assessed using the OXITEST method at temperatures of 90, 100, 110, and 120 °C. These tests enabled the calculation of kinetic parameters such as reaction rates and activation energies, crucial for understanding the inhibition role of antioxidants during oxidative degradation. Activation energy for antioxidant consumption, determined using the Arrhenius equation, was found to be 81.39 kJ mol−1 for fruit peel extracts, 77.73 kJ mol−1 for pulp extracts, and 63.85 kJ mol−1 for root bark extracts. The higher activation energy for fruit peel extracts suggests that they are more effective at preventing oxidation, especially under high-temperature conditions. Enthalpy, entropy, and Gibbs free energy parameters were calculated using the Eyring equation, indicating a nonspontaneous endothermic process for the antioxidant samples. The study found an inverse relationship between antioxidant concentration and rate constants, demonstrating the antioxidants' effectiveness in slowing down the oxidation process. These kinetics and energetics analyses provide detailed insights into how antioxidants function, facilitating the optimization, selection, and validation of their efficiency in stabilizing biodiesel.
Hermetia illucens pupae casings and biogas slurry activated carbon electrodes for Cd2 + removal from aqueous solutions using capacitive deionization
(Elsevier, 2025-04-01) Panja, Eva; Alfredy, Tusekile; Elisadiki, Joyce; Jande, Yusufu
This study examined capacitive deionisation’s effectiveness for recovering Cd2+ from water using novel carbon-based electrodes derived from Hermetia illucens pupae casings (PC) and biogas slurry (BG). Activated carbon (AC) was produced through carbonization at 500 °C and chemical activation (KOH) at 700 °C. The Brunauer-Emmett-Teller method, Scanning Electron Microscope, X-ray diffractometer, Fourier transform infrared, X-ray photoelectron spectroscopy, Raman spectroscopy, and contact angle measurement were performed on AC. Electrochemical impedance spectroscopy and cyclic voltammetry were used to test the electrochemical properties of carbons. Prepared AC possessed high specific surface areas of 549 m2/g and 927 m2/g for pupae casings and biogas slurry. Electrochemical tests revealed that PC-700 has a high specific capacitance of 271.9 Fg−1 and 105.8 Fg−1 for BG-700. Two concentrations of CdCl2 (5 mg/L and 10 mg/L) were used in a batch mode for the CDI test. Electrodes show an impressive cadmium removal efficiency of approximately 91 % and 56 % for PC and BG electrodes, respectively. Electro-sorption capacity was 10.9 mgg−1 and 2.1 mgg−1 for PC and BG electrodes, respectively. This work demonstrates the potential of PC-derived electrodes in CDI technology for recovering heavy metals from water.
Compressive strength optimization of the ambient-cured metakaolin-based geopolymer mortar using the Taguchi design approach
(Elsevier, 2025-05-16) Hamisi, Hashimu; Chambua, Safiel; Mansouri, Said; Majdoubi, Hicham; Jande, Yusufu; Tamraoui, Youssef; Hilonga, Askwar
This study utilized raw natural kaolinite sourced along Pugu hills, Tanzania, as the aluminosilicate source. To optimize the compressive strength, nine (9) metakaolin geopolymer formulations were activated using the Taguchi technique at various Na2SiO3/NaOH mass ratios, NaOH concentrations, and alkaline/binder ratios. The ideal parameters were 12 M, 2.5, and 0.8 Na2SiO3/NaOH mass ratios, NaOH concentration, and alkaline/binder ratios, respectively, resulting in a compressive strength of 70.38 MPa. When the optimized geopolymer was exposed to a higher temperature, its compressive strength increased by 15.57 % at 200°C compared to room temperature. Compressive strength decreased with exposure over 200°C, and weight loss and water absorption were directly correlated with this. The SEM results show that the former lacks a well-linked geopolymer network when comparing weak and superior formulations. High-strength formulations are verified to include higher levels of orthoclase and albite, according to Rietveld refinement and XRD research. The XRD patterns showed the development of sanidine, chrysotile, and nepheline crystalline phases at temperatures higher than 200°C, which may have contributed to the decrease in strength of the geopolymer specimens
Electro-spun transparent film from banana pseudo-stem native cellulose using N-methylmorpholine-N-oxide solvent system
(Elsevier, 2025-04-21) Livifile, Silla; Tarus, Bethwel; Kisula, Lydia; Kivevele, Thomas; Thomas, Yusufu
The study-utilized electrospinning to prepare a transparent film from native cellulose extracted from banana pseudo stems. The process of electrospinning was performed at room temperature conditions, after which the cellulose film was obtained through water coagulation. Dimethyl sulfoxide and dimethylformamide were added to the electrospinning solution to adjust the surface tension, viscosity, and conductivity of the prepared solutions. The formed thin film was characterized using Infrared spectroscopy (IR) and X-ray crystallography tests to confirm the elimination of non-cellulosic materials during extraction. It was revealed that the banana fibers were dominated by crystallinity and converted from cellulose-I to cellulose-II after dissolution in N-methyl morpholine N-oxide (NMMO). Scanning electron microscopy images revealed that fiber and electro-spun film morphologies could be achieved by varying sodium hydroxide solution concentration and solution parameters during fiber treatment and electrospinning. Concentration of 17.5 % (wt./v)of the alkaline solution showed to be more effective in changing the surface morphology of the fiber. The structure and mechanical characteristics of the films were influenced most by the concentration of banana native cellulose, process stability, and the solidification of the electro-spun fibers. The film exhibited an initial degradation temperature of 165°C, a light transmittance of 83.3 % in the visible UV range, and a tensile strength ranged from 5.83 MPa to 8.13 MPa. This performance highlights its potential applications in various fields, including packaging and biomedical engineering.
Modelling and optimization of different pozzolanic materials in the durability of cement composite by central composite design
(Elsevier, 2025-04-19) Fode, Tsion; Jande, Yusufu; Kivevele, Thomas
The production of Ordinary Portland Cement (OPC) requires high temperatures and significant energy consumption, leading to environmental pollution and posing challenges to the sustainability of green cementing materials. To address this, numerous researchers have explored replacing cement with various supplementary cementitious materials, such as blast furnace slag, active limestone, and bentonite, in concrete or mortar. However, optimizing the combined use of these materials to achieve maximum durability in mortar remains a novel area of study. This research models and optimizes the effects of replacing OPC with blast furnace slag, active limestone, and bentonite in mortar using the central composite design method. The findings reveal that increasing the content of bentonite along with either blast furnace slag or limestone from 0% to 20% significantly minimizes strength degradation due to sulfuric acid exposure, improves heat resistance, and lowers water absorption at 28 days. The optimal substitution levels were found to be 20% for both blast furnace slag and limestone, and 18.54% for bentonite. The optumal result reduced damage from sulfate attack by 33.4%, strength loss under high temperatures by 69.04%, and water absorption by 98.58% when compared to the control sample. These outcomes were validated experimentally with a 95% confidence level. Overall, incorporating these SCMs not only improves the durability of mortar but also supports environmental sustainability by reducing CO₂ emissions due to OPC production.
Tree demographics and soil charcoal evidence of fire disturbances in an inaccessible forest atop the Mount Lico inselberg, Mozambique
(John Wiley & Sons, 2024-10-24) Courtney-Mustaphi, Colin; Platts, Philip; Willcock, Simon; Timberlake, Jonathan; Osborne, Jo; Matimele, Hermenegildo; Osgood, Hanniah; Muiruri, Veronica; Gehrels, Maria; Bayliss, Julian; Marchant, Rob
Societal Impact Statement Highland forests of Mozambique have been strongly modified by human activities for millennia. Some highlands have sheer rock cliffs and are highly inaccessible to people and appear relatively undisturbed. Evidence from the forest and soils of inaccessible Mount Lico show that the fire regime has changed over the recent millennia. As climate and fire regimes continue to change, management of highland ecosystems will be crucial to sustain the high biodiversity and mountain-water resources that provide key ecosystem services to people living close to these forests. Summary The sheer rock cliffs of the Mount Lico inselberg, northern Mozambique, is relatively inaccessible to people. A 0.57 km2 forest covers the top of the isolated mountain, and the tree demographics and soil offer an opportunity to investigate the long-term fire ecology of the forests of the western, leeside of the mountain and potential for changing regional hydroclimate of the Late Holocene. On the western side of the mountaintop, a 20 × 20 m plot was surveyed for tree taxa, heights and bole diameters. A 220 cm deep pit was dug into the forest soil and analysed to describe the soil texture and carbon content. Charcoal was quantified on sieved subsamples and classified into charcoal morphologies that were then grouped by how readily entrainable on an index score. Three radiocarbon dates were collected from pieces charcoal. The forest is a combination of montane and woodland tree taxa that differed from the older, more mesic eastern side and reflected differential disturbance patterns. The reddish loam soils dated to the Middle Holocene. Charcoal was present in all soil subsamples and varied little until increasing consistently during the past millennium. The charcoal morphologies suggested a combination of locally derived charcoal and charcoal derived from the surrounding lowlands with the latter increasing in the past centuries. Few Holocene paleoenvironmental records have been developed from tropical soils in Africa and are useful in locations that do not host lakes and wetlands. Both tree demographics and soil charcoal suggest that changing forest disturbance regimes began during the past millennium. An understanding of history informs future conservation and appropriate management of these special places.
Life Cycle Assessment and Cost Analysis of Locally Made Solar Powered Cooler for Vaccine Storage.
(Elsevier, 2025-04-15) Mbugano, Milton; Selemani, Juma; Kichonge, Baraka; Mwaijengo, Grite; Mwema, Mwema
Storing vaccines and perishable food in regions without access to the national grid presents significant challenges. Solar power generation technologies have emerged as a viable alternative solution to address these issues. This study conducted a life cycle assessment (LCA) and cost analysis (CA) of the locally developed solar-powered cooler to assess its techno-economic viability and potential environmental impacts. The cooler was designed to preserve vaccines and perishable foods for use, especially in areas with no electricity connectivity, as a cheaper alternative to electricity-powered coolers. The results of LCA show that battery manufacturing was a slightly higher contributor to environmental impacts across various indicators, with terrestrial ecotoxicity identified as the highest impact among other environmental impacts. Cost analysis results further revealed that a solar-powered cooler project demonstrated a positive economic outlook, with the unit manufacturing cost estimated at USD 2682. This quantitative analysis of life cycle and cost will help decision-makers comprehend both the economic aspects and environmental impacts throughout the life cycle of locally manufactured solar-powered coolers. Such insights will be instrumental in enhancing the sustainability of these products.
Agro-Waste-Derived Hybrid Biochar Exhibits High-Efficiency Removal of Endocrine-Disrupting Compounds
(Springer International Publishing, 2025-04-11) Kasambala, Hildegard; Rwiza, Mwemezi; Mpumi, Nelson; Mwema, Mwema; Njau, Karoli
Poor waste management of the products and products used in water sources becomes a problem for living organisms’ health. Using biosorbent from agro-waste materials becomes the solution for waste management and wastewater treatment. This study investigated the removal of progesterone from aqueous solutions using a biochar adsorbent derived from mixed banana and mango peels. The biosorbent shows high progesterone removal of 97.8 ± 0.02% at 700℃ preparation temperature at an optimal biosorbent concentration of 0.50 g and pH of 8. Kinetic studies showed that the adsorption followed a pseudo-second-order model. Isotherm analysis revealed that the adsorption data best fitted the Freundlich model (R2 = 0.96), with a maximum adsorption capacity (qmax) of 307 mg g−1, indicating multilayer adsorption with a heterogeneous surface. The Brunauer–Emmett–Teller (BET) surface area was 652 m2g−1 with abundant functional groups verified by Fourier Transform Infrared Spectroscopy (FTIR). The Scanning Electron Microscopy image (SEM) indicated that the biochar is porous, contributing to its effectiveness as an adsorbent. Thermodynamics results indicate that the spontaneous nature of adsorption reveals the process. The findings proved the potential of using agricultural mixed waste-derived biochar containing various chemical and physical characteristics as an effective and sustainable adsorbent to remove endocrine disruptors. This technique addresses environmental concerns about water hormone pollution and promotes sustainable waste management practices, but the gradual decrease in adsorption efficiency highlights the importance of optimizing the biochar's chemical composition and structural reliability to maximize its performance.
Kinetics and energetics of biodiesel oxidation stability: The impact of Uapaca kirkiana-derived natural antioxidants
(John Wiley & Sons, Ltd., 2025-03) Kahimbi, Henry; Kichonge, Baraka; Kivevele, Thomas
Despite considerable progress in understanding biodiesel autoxidation inhibition, the kinetics and energetics of the inhibition reactions involving natural antioxidants remain underexplored. Most existing research on natural antioxidants has focused on enhancing oxidation stability and other fuel properties. This study aimed to investigate the oxidative stability of croton biodiesel (CBD) and assess the kinetics and energetics of natural antioxidants derived from the roots, pulp, and fruit peels of the Uapaca kirkiana plant. The oxidation stability of biodiesel samples was assessed using the OXITEST method at temperatures of 90, 100, 110, and 120 °C. These tests enabled the calculation of kinetic parameters such as reaction rates and activation energies, crucial for understanding the inhibition role of antioxidants during oxidative degradation. Activation energy for antioxidant consumption, determined using the Arrhenius equation, was found to be 81.39 kJ mol−1 for fruit peel extracts, 77.73 kJ mol−1 for pulp extracts, and 63.85 kJ mol−1 for root bark extracts. The higher activation energy for fruit peel extracts suggests that they are more effective at preventing oxidation, especially under high-temperature conditions. Enthalpy, entropy, and Gibbs free energy parameters were calculated using the Eyring equation, indicating a nonspontaneous endothermic process for the antioxidant samples. The study found an inverse relationship between antioxidant concentration and rate constants, demonstrating the antioxidants' effectiveness in slowing down the oxidation process. These kinetics and energetics analyses provide detailed insights into how antioxidants function, facilitating the optimization, selection, and validation of their efficiency in stabilizing biodiesel.
Applications of Natural Rocks as Heat-Storage Materials for Food Drying in Sub-Saharan Africa
(Trans Tech Publications Ltd, 2025-10-03) Loemba, Aldé; Kichonge, Baraka; Kivevele, Thomas
Natural rocks are emerging as a viable solution for solar heat storage in Sub-Saharan Africa due to their low cost and accessibility, as well as their ability to reduce energy costs and reliance on solar energy. This study review research on applications of natural rocks as heat-storage materials for food drying in Sub-Saharan Africa. Findings of this study indicate that current research on the combination of drying systems with thermal energy storage systems using natural rocks as storage material focuses on indirect solar dryers (66.67%), mixed mode solar dryers (16.67%), and solar-assisted heat pump dryers (16.67%). These dryers perform admirably, particularly in extreme weather conditions and when there is no sunlight. The findings show that using natural rocks as a storage medium can increase the efficiency of dryers by up to 17.48%, reduce drying time by as much as 50%, and extend the drying operation by 2 to 4 hours after sunset. This study also identifies and proposes key areas for further research. In particular, more attention is needed to characterize the thermal properties of the storage materials used, as this aspect is often underexplored in African studies. Understanding these properties is essential for optimizing the performance of solar dryers and making informed choices about which materials to use. In addition, the techno-economic analysis of all these dryers is neglected, making it difficult to assess the economic impacts of these technologies and facilitate their adoption in communities. Exergoeconomic analysis should also be carried out in order to facilitate optimization and understand the actual efficiency of these dryers.

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