Browsing by Author "Sarah Kizza-Nkambwe"

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    Assessing the economic feasibility of integrated waste to use systems for Uganda
    (Avanti Publishers, 2021-09-08) Miria Frances Agunyo; Sarah Kizza-Nkambwe; Kukunda Elizabeth Bacwayo
    Waste and sanitation Management is a major challenge in urban areas in Uganda where waste is composed of at least 70% organic content and is basically collected and disposed of in landfills. While 90% of the sanitation facilities used are onsite systems often requiring additional treatment of sewage and faecal matter sewage, yet faecal and sewage sludge treatment plants are few. The projected population increase is expected to further influence urbanization, increasing the need for basic waste and sanitation services. Integrated Waste to Use systems that consider combined management of organic waste streams i.e. biowaste, animal waste, sewage and faecal sludge, could be a viable solution for the urban areas. The systems which consist of a combination of anaerobic digestion, composting, incineration and solar drying technologies promote resource recovery in the form of biogas, briquettes and organic fertilizer. The economic feasibility of the Waste to Use systems was carried out and the results indicated that the feasibility of the systems was positively influenced by the inclusion of the anaerobic digestion process, which allowed for recovery of biogas and digestate as organic fertilizer. Furthermore, a combination of low system investment costs, increased revenues from resource recovery, consideration of equity capital of at least 30%, interest rate of at most 10% and fugitive emissions less than 7 % would positively influence the economic feasibility of the system alternatives.
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    Compost quality of a peri-urban waste composting facility: A case of Mukono municipality, Uganda
    (Taylor & Francis, 2023-08-21) Sarah Kizza-Nkambwe; Maxmillan Mpewo; Junior Senyonga Kasima; Kheria Mfuranzima
    Effective management of windrow-based composting technology in developing cities is a major challenge, especially for municipal authorities mandated to offer these services. Poorly managed waste composting systems could affect the quality of compost and cause complex environmental impacts. The aim of this study was to assess the quality of compost of a waste composting facility in Mukono municipality, central Uganda. Mature compost samples were collected from windrows in the waste composting facility and the samples analyzed for physicochemical parameters (temperature, pH, moisture content, organic matter, total nitrogen, total phosphorus, and potassium) and for heavy metals (lead, cadmium, copper) and metalloids (arsenic). To assess the quality of the compost, the analyzed results of the samples were compared with common ranges for compost quality. Concentration of heavy metals ranged between 0.01 mg/l (cadmium) and 0.4 mg/l (copper). Except for alkaline pH (9.1), which was higher than the recommended range for mature compost quality, all physicochemical parameters and heavy metals were within common ranges for compost quality. Moisture content and pH correlated with heavy metals, 0.75 and 0.78, respectively. Mean total nitrogen and phosphorus were 0.8% and 0.4%, respectively, while organic matter was 21.7% and potassium 0.3%. Compost quality did not differ between seasons (P = 0.05). Based on the study results, continuous investigative research is recommended to safeguard the compost quality.
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    Evaluation of Agricultural Waste-Based Briquettes as an Alternative Biomass Fuel for Cooking in Uganda
    (East African Nature & Science Organisation, 2024-02-27) Sarah Kizza-Nkambwe; Junior Senyonga Kasima; Maxmillan Mpewo; Miria Frances Agunyo
    Wood fuel has been adopted as a feasible alternative to cooking energy sources in efforts to replace fossil fuels. However, the exorbitant use of wood fuel has raised concern as it is the major cause of forest cover loss in Uganda. Briquettes have been recommended as sources of cooking energy with potential to substitute wood fuel. Unfortunately, sawdust, a product of deforestation, is the primary material used in making briquettes in Uganda. This instead augments the problem of fuel-induced deforestation. Agricultural wastes could potentially be converted into briquetting materials for generation of cooking energy, although these are less studied in Uganda. Thus, this study established the potential of agricultural wastes as alternative briquetting materials for use in cooking. Four fuel types: charcoal from Mangifera indica, firewood of Eucalyptus grandis, carbonized and non-carbonized briquettes from agricultural wastes, all from within Mukono District were used for the study. Laboratory based experiments were used to determine the physico-chemical characteristics of the fuels. Data were analysed using R software, Ver. 4.2.3. Carbonised briquettes’ mean performance measures were higher than conventional fuels (p≤0.05) and non-carbonised briquettes. The amount of energy required to attain experimental boiling point of water was higher (p≤0.05) in conventional fuels and non-carbonised briquettes than in carbonised briquettes. Duration to boil 5 litres of water was least with the conventional fuel sources. All the fuel sources’ emissions exceeded the maximum range recommended for indoor carbon monoxide levels. However, the particulate matter emission was lower in carbonised briquettes and charcoal than the other fuel sources. Agricultural waste-based carbonised briquettes could effectively be used as an alternative cooking energy source in Uganda. The study recommends conducting cost benefit analyses on the use of agricultural waste-based briquettes as cooking energy sources.
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    Plant Communities as Indicators of Anthropogenic Disturbance on a Peri-Urban Tropical Wetland of Lutembe Bay Wetland System, Uganda
    (Taylor & Francis, 2024-08-21) Nuubu Takuwa; Eleanor Wozei; Sarah Kizza-Nkambwe; Geoffrey Malinga; George Kilande; Joel Kinobe
    Wetland degradation linked to peri-urban anthropogenic pressures is a major threat to wetland biodiversity. However, little is known of the response of biodiversity to this disturbance. Biotic indicator species are useful for assessing the health and ecological integrity of wetlands. This study evaluated patterns of plant species richness and composition and determined species character izing each of three differently disturbed wetland sites ofLutembe Bay Wetland, a peri-urban Ramsar Wetland of International Importance and an Important Bird Area in Uganda. The study revealed that total nitrogen decreased following wetland degradation, but total phosphorous was not affected; pH values were <5.5, while OM content was low in the lightly and heavily (2.5–4.4%) degraded sites. While plant species richness did not differ among the sites, total species richness was higher in heavily disturbed, compared to lightly disturbed and relatively intact sites. Community composition differed significantly among the three sites. Indicator plant species were then identified which could be employed as a rapid assessment tool to infer the level of degradation in the sustainable management of Afrotropical wetlands by practitioners. Results show that continued unsustainable use of wetlands results in changes in soil properties and plant species composition, highlighting the need to restore anthropogenically disturbed parts of wet lands and to prevent further degradation of less degraded areas.