Browsing by Author "Mwema, Mwema"

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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.
A comprehensive life cycle assessment of sisal yarn production: Unveiling sustainability and resource optimization hotspots
(Elsevier, 2025-01-19) Kahigi, Nickson; Mkunda, Josephine; Mwema, Mwema; Machunda, Revocatus
This study presents a comprehensive life cycle assessment (LCA) of sisal yarn production, covering key phases such as cultivation, transportation, decortication, brushing, baling, and yarn making to assess the environmental impacts associated with the production of 1 kg of sisal yarn. The results show that cultivation contributes the most to global warming potential (7.29 kg CO eq, 51% of total emissions) and terrestrial ecotoxicity (112.02 kg 14-DCB eq, 97.7%), driven largely by the excessive use of pesticides, herbicides, and fertilizers. Decortication contributes significantly to marine eutrophication (83.7% of total impacts) and global warming (5.52 kg CO eq, 40%). Although yarn making accounts for a smaller share of the global warming potential (0.97 kg CO eq, 6.8%), it has a notable impact on human toxicity (contributing 21.7% to non-carcinogenic toxicity) and fossil fuel depletion (305.8 g oil eq, 10% of the total). A sensitivity analysis indicates that reducing chemical inputs, improving energy efficiency, and optimizing water use can reduce environmental impacts by up to 30%, lowering global warming potential to 11.59 kg CO eq in the improvement scenario. These results align with Sustainable Development Goals (SDGs) on responsible production (SDG 12), climate action (SDG 13), and life on land (SDG 15), positioning sisal yarn as a sustainable alternative to synthetic fibers. Future research should focus on incorporating renewable energy, expanding region-specific LCA inventories, and exploring social and economic sustainability to further enhance the sisal value chain’s sustainability.
A comprehensive review on the distribution of per- and poly-fluoroalkyl substances in the environment across Sub-Saharan Africa revealed significant variation in their concentrations
(Elsevier, 2024-08) Kasambala, Hildegard; Rwiza, Mwemezi; Mpumi, Nelson; Mwema, Mwema; Machunda, Revocatus; Mtei, Kelvin; Njau, Karoli
Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic chemicals known for their widespread use in various industrial and consumer products. They enter the food chain via contaminated water, air, and soil, resulting in bioaccumulation in plants, fishes, foods, human milk, and blood serum. Here, we critically reviewed the literature published from 2005 to 2021 on the occurrence and distribution of Perfluorooctanoic acid (PFOA) and perfluoro-octane sulfonate (PFOS) as the most occurring PFAS in the aquatic environment in sub-Saharan Africa (SSA). To our knowledge, this is the first paper to review the status of PFAS in the SSA environment. This review found that almost all matrices studied in SSA regions have been polluted by PFAS with varying concentrations. This information suggests that the levels of PFAS in the environment deserve immediate attention. Furthermore, SSA faces unique challenges in understanding and managing PFAS contamination due to the scarcity of data in specific regions and the need for more administrative guidelines for monitoring PFAS in water. This review provides vital baseline information on the occurrences, distribution and contributing factors for their distribution in the SSA environment for better understanding to protect the environment and public health, and to develop sustainable solutions for the PFAS growing concern.
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 chal- lenges. 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 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.
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.
Prevalence of chronic obstructive pulmonary disease and associated factors among smallholder fish vendors along coastal areas in Tanzania
(BMC Pulmonary Medicine, 2023-08-02) Onesmo, Brigitha; Mamuya, Simon; Mwema, Mwema; Hella, Jerry
Background In Tanzania little is known about how the respiratory system of small-holder fish vendors is affected by occupational exposure to biomass smoke and other associated factors. This study assessed the prevalence of lung obstruction and associated factors among small-holder fish vendors along coastal areas in Tanzania. Methods A cross-sectional descriptive study was conducted in Bagamoyo and Kunduchi fish markets along coastal areas of Tanzania. Environmental air pollutant levels and composition were measured using a hand-held device. A standardized questionnaire was used to assess respiratory symptoms while EasyOne spirometer was used to test for lung function among small-holder fish vendors. Chronic Obstructive Pulmonary Disease (COPD) was defined as FEV1/ FVC below the lower limit of normal. Data were analyzed using STATA Version 17. Descriptive statistics was performed and logistic regression analysis was used to determine factors that are associated with poor lung function presented as crude and adjusted odds ratio and their 95% confidence intervals. Results A total of 103 participants were included in the study who were predominantly males 82 (79.6%). The participants’ mean age was 35.47 (±8.77 SD) years. The hourly average concentration levels of PM1, PM2.5, PM10, and CO exposure during fish frying were 653.6 (±206.3 SD) μg/m3 , 748.48 (±200.6 SD) μg/m3 , 798.66 (±181.71 SD) μg/m3 and 62.6 (±12.3 SD) ppm respectively which are higher than the WHO recommended limits. The prevalence of COPD was found to be 32.04% (95% CI 0.23–0.42). Most of the participants reported respiratory symptoms like coughing, wheezing, sputum production and breathlessness during performing their daily activities. Conclusion Findings suggest that three out of ten participants had COPD and the major environmental air pollutants (PMs and CO) concentration levels were too high, suggesting that occupational exposure to biomass smoke may be a risk factor. This calls for effective approaches to reduce exposure and prevent known acute and chronic respiratory diseases that are associated with such exposure to air pollutants. Also the study calls for follow up or cohort studies to be conducted in this area
Unraveling the potential of sisal fiber in sustainable innovation: A bibliometric perspective
(Taylor and Fransis, 2025) Kahigi, Nickson; Mkunda, Josephine; Mwema, Mwema; Machunda, Revocatus
Sisal fiber has increasingly attracted attention as a sustainable bio-based material due to its biodegradability, availability, and relevance to circular economy initiatives. Given its underutilization in high-impact applications and the limited integration of East African contributions, there is a growing need to assess the global research dynamics surrounding sisal fiber. This study hypothesizes that a bibliometric approach can reveal critical patterns, emerging themes, and collaboration gaps in sisal fiber research over the past decade. Using 59 curated articles from the Dimensions database (2012–2024), the study employed VOSviewer and Excel to analyze thematic evolution, citation patterns, and co-authorship networks. Findings show a rapid growth in publications from 2021 to 2024 (67.8%), led by Brazil and India, with emerging focus areas including waste valorization, biocomposites, and LCA-based sustainability assessments. The study concludes that targeted research investment, policy support, and international collaboration are essen-tial to enhancing sisal fiber’s role in global sustainability transitions.