Browsing by Author "Vuai, Said Ali Hamad"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    A comparative in-vitro study on antimicrobial efficacy of on-market alcohol-based hand washing sanitizers towards combating microbes and its application in combating Covid-19 global outbreak
    (Heliyon, 2022) Vuai, Said Ali Hamad; Sahin Khalfani Salimi,; Sule, Mtabazi Geofrey
    The coronavirus disease 2019 (COVID-19) outbreak has created endless social, economic, and political fear in the global human population. Measures employed include frequent washing hands and using alcohol-based hand sanitisers and hand rubs as instant hand hygiene products. Due to the need to mitigate the pandermic, there is an increase in the local production of alcohol-based hand sanitisers, whose quality and efficacy against germs and the virus are questionable. Therefore, the current study investigated the in-vitro antimicrobial efficacy of on-market alcohol-based handwashing sanitizers used to mitigate the Covid-19 global outbreak toward combating enveloped bacteria such as E. Coli, P. aeroginosa, S. aureus, and a fungus C. albicans. The antimicrobial effectiveness of alcohol-based hand sanitizer was performed by the agar well diffusion method, and the analysis of variance (ANOVA) model was used for statistical analysis. Results indicate that alcohol hand-based sanitizers were more effective in inhibiting P. aeroginosa, with a mean zone of inhibition of 12.47 mm, followed by E. coli, a gram negative bacterium with a mean zone of inhibition of 12.13 mm than both S. aureus and C. albicans as gram positive bacteria, and fungi respectively had the same inhibition average of 11.40 mm. The overall mean diameter of inhibition was statistically significantly different among the fifteen tested products. Only one brand of alcohol-based hand sanitizers was the most effective in inhibiting microbes. Less effective sanitizers may impair Covid 19 mitigation efforts and put the population at risk instead of protecting it. Indicating the need for all materials used to mitigate Covid 19 pandermic, including alcohol-based hand sanitizers, to be evaluated and monitored to ensure public health safety
  • Thumbnail Image
    Item
    Attenuation of nitrate from Aqueous Solution using Raw and Surface Modified Biosorbents from Adansonia Digitata Fruit Pericarp
    (Elsevier, 2022-07-14) Mihayo , David; Vegi, Maheswara Rao; Vuai, Said Ali Hamad
    The prevalence of nitrate in potable water is a serious environmental concern. Several methods for eliminating nitrate from water have been made and implemented. During the course of this research, raw (RADFP) and surface-modified fruit pericarp (SMADFP) biosorbents derived from the Adansonia digitata plant were applied in order to remove nitrate from an aqueous solution. The external features of the biosorbents were studied with the aids of SEM and BET. The FT-IR spectrometer was utilized for identification of the functional groups of the ad sorbents. A UV-Vis device was used to quantify the nitrate concentration. The adsorbents under investigation exhibit a heterogeneous pore structure with a considerable number of mesopores, with surface areas of 361.527 and 379.877 m2 per gram for RADFP and SMADFP, respectively. FT-IR spectra revealed the presence of carboxyl, hydroxyl, carbonyl, and halogen groups on the adsorbent. The maximum nitrate removal efficiencies of RADFP and SMADFP were 64.55 and 88.95%, respectively. The maximum adsorption efficiencies are achieved when the pHis 2, the starting concentration is 27.50 mg/L, the contact period is 75.00 min, and the amount of biosorbent is 5.50 g. RADFP and SMADFP have a removal capacity of 12.45 as well as 25.18 mg per gram and adsorption intensity of 3.2300 and 5.4500, respectively. The investigational values for the elimination of nitrate ions concurred well to both Freundlich and Langmuir models with R2 values of 0.99917 and 0.99763 for RADFP and SMADFP, respectively, and pseudo-second-order kinetic model with R2 values of 0.99817 and 0.99947, respec tively for RADFP and SMADFP. It can be concluded that SMADFP is a relatively better biosorbent than RADFP, which will be utilizable for the remediation of nitrate from an aqueous solution.
  • Thumbnail Image
    Item
    Characterization of MSW and related waste-derived compost in Zanzibar municipality
    (wm&r, 2010) Vuai, Said Ali Hamad
    The spread of municipal solid waste (MSW) in Zanzibar municipality has been associated with environmental pollution, unpleasant city conditions, contamination of water sources and coastal areas together with harbouring of malaria vectors. The contamination has a close relationship with eruption of diarrhoea, cholera and typhoid which claim the lives of the residents. Most of the wastes are of domestic and market origin and have the potential for compost production. This study examined the possibility of composting MSW from Zanzibar municipality as an alternative way of SW management and assessed the nutrient contents of the compost for application in agricultural production. Two major classes of SW were selected for the study: munic ipal solid waste and rice milling by-products. The samples were composted aerobically and anaerobically. The results showed that aerobic composting reduced about 60% of the waste volume. This volume reduction suggests that composting can be a promising SW management technique by reducing the large demand of space for landfilling. Municipal solid waste composted under anaerobic conditions produced compost with relatively higher concentrations of dissolved species than that produced under aerobic conditions. The trace metal contents were higher in MSW than in rice milling by-products. It was found that the unmanaged compost collected from the dumping site had low nutrient contents and was enriched with trace metals. Generally, physico-chemical characteristics, nutrients and trace metal levels suggest that Zanzibar municipal solid waste can produce high quality compost for application to a wide range of soil types to improve their fertility, under proper management.
  • Thumbnail Image
    Item
    Ecological Consequences of Antibiotics Pollution in Sub-Saharan Africa: Understanding Sources, Pathways, and Potential Implications
    (ELSEVIER, 2025-01-23) Ripanda, Asha; Rwiza, Mwemezi J.; Nyanza, Elias Charles; Hossein, Miraji; Alfred, Mateso Said; Mahmoud, Alaa El Din; Murthy, H.C. Ananda; Bakari, Ramadhani; Vuai, Said Ali Hamad; Machunda, Revocatus L.
    In Sub-Saharan Africa (SSA), the increasing use of antibiotics in human and veterinary medicine, combined with inadequate waste and water management systems, has intensified the problem of antibiotic pollution. Untreated or partially treated wastewater from industries, agricultural runoff, residential areas, and healthcare facilities is frequently discharged into the environment, often used for irrigation, contributing to antibiotic accumulation, the spread of resistance genes, and the rise of antibiotic resistance, posing serious threats to public health and environmental sustainability. The region's climatic conditions favour the survival and proliferation of microbial communities, including pathogens. Additionally, the high prevalence of infectious diseases such as HIV/AIDS, tuberculosis, and malaria, which often necessitate antibiotic use, further amplifies the issue. Systemic challenges, including poor waste management, inadequate or absent wastewater treatment infrastructure, weak regulatory enforcement, and the over-the-counter sale of antibiotics, exacerbate the crisis. Limited healthcare access often results in self-medication and improper antibiotic use, accelerating resistance spread. Evidence shows antibiotics in surface water, groundwater, effluents, food crops, environmental samples, and aquatic organisms, indicating their potential circulation through the food chain. However, a lack of comprehensive data on antibiotic pollution and its impacts on aquatic ecosystems in SSA hampers a thorough understanding of its scope and long-term effects. Addressing this crisis requires identifying contamination hotspots, evaluating ecological impacts, and establishing robust, region-specific regulatory frameworks to ensure environmental and public health safety.
  • Thumbnail Image
    Item
    Water Hyacinth Derived Activated Carbon Electrode Materials for Water Defluoridation Using Capacitive Deionization Technology
    (ELSEVIER, 2025) Kalilo, Hassan Johnson; Elisadiki, Joyce; Vegi, Maheswara Rao; Vuai, Said Ali Hamad
    Safe water is a vital component of human life that requires purification to reduce the concentration of ionic pollutants using appropriate water treatment techniques, such as capacitive deionization (CDI) water treatment technology. The porous activated carbon electrode materials have prepared via the carbonization of water hy- acinth plants followed by chemical activation using KOH at different temperatures (400-700◦C with an incre- ment of 100◦C) labeled as CWH-400, WHAC-500, WHAC-600 and WHAC-700 all being activated for 1 h where CWH represents carbonized water hyacinths and WHAC represents water hyacinths activated carbon. The activation temperature has a significant effect on the specific surface area of the porous carbon prepared, as it increases from 464.67 m²/g for CWH-400 to 1020.01 m²/g for WHAC-700. The defluoridation experiments were done using water samples with initial fluoride concentrations of 4.21, 4.61 and 3.51 mg/L for water samples from Arusha (A), Manyara (B) and Shinyanga (C) respectively when the 2 V was supplied to the cell with 10 mL/ min flow rate at 3 hours charging time. The defluoridation results were 1.28, 1.37, and 1.15 mg/L for water samples A, B, and C, respectively. The WHAC-700 electrode was found to possess a capacitance of 501.89 F/g, exhibiting removal efficiencies of 69.60%, 70.28%, and 67.24% for water samples from Arusha (A), Manyara (B), and Shinyanga (C), respectively, at a potential of 2 V with a charging time of 3 hours. Therefore, the water hyacinth plants are suitable precursors for preparing porous activated carbon electrodes to be used in a CDI cell for the defluoridation of any water sample