Browsing by Author "Kasedde, Hillary"

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    Active Pharmaceutical Ingredients Sequestrated fromWater Using Novel Mesoporous Activated Carbon Optimally Prepared from Cassava Peels
    (Water, 2022) Kayiwa, Ronald; Kasedde, Hillary; Lubwama, Michael; Kirabira, John Baptist
    The increasing occurrence of active pharmaceutical ingredients (APIs) in water systems coupled with their recalcitrance to conventional water treatment methods calls for research into more eco-friendly and cost-effective curbing media. Mesoporous cassava peel activated carbon (CPAC) was prepared under conditions derived from optimizing the surface area and yield with the temperature and holding time as the model inputs using the response surface methodology. The sequestration potential and mechanisms of the resultant activated carbon (AC) for active pharmaceutical ingredients from wastewater were studied using batch experiments. The CPAC adsorption kinetics and isothermal mechanisms for the three pharmaceuticals (carbamazepine (CBZ), clarithromycin (CLN), and trimethoprim (TRM)) were studied in both wastewater and Milli-Q water. The API concentrations were measured using liquid chromatography coupled to a mass spectrometer (LC-MS) system. The maximum removal efficiencies were 86.00, 58.00, and 68.50% for CBZ, CLN, and TRM for wastewater, which were less than those from the Milli-Q water at 94.25, 73.50, and 84.5%, respectively. The sorption process for the CLN was better explained by the Freundlich model, whereas the CBZ and TRM adsorption processes could suitably be explained by both the Langmuir and Freundlich models. At an initial concentration of 20 mgL􀀀1 for all APIs and a CPAC dosage of 2.0 gL􀀀1, the maximum adsorption capacities were 25.907, 84.034, and 1.487 mgg􀀀1 for CBZ, TRM, and CLN, respectively. These results demonstrated the potential of CPAC to remove APIs from water, with its sequestration potential being more exhibited after the removal of the organic matter owing to the lower competition for active sites by the APIs. Additionally, positive adsorbates were better removed than negatively charged adsorbates due to the dominance of anions in the cassava peel lattice.
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    Characterization of Biogas Digestate for Solid Biofuel Production in Uganda
    (Scientific African, 2021) Ogwang, Isaac; Kasedde, Hillary; Nabuuma, Betty; Kirabira, John Baptist; Lwanyaga, Joseph Ddumba
    In this study, suitability of digestate from anaerobic digestion of cow dung, pig dung, and human waste feedstock as a solid fuel for thermal applications was investigated. The digestate was obtained at different retention times from laboratory scale and household digesters and later characterized. Carbonized briquettes were produced from the digestate followed by their physico-chemical characterization and assessment for combustion and mechanical properties. Results of the proximate analysis of the digestate were: moisture content (6.1 to 18.3%), volatile matter (27.9 to 47.7%), ash (15.0 to 48.9%), and fixed carbon (9.1 to 17.1%). The ultimate analysis results for the digestate were: carbon (19.5%), hydrogen (3.3%), oxygen (20.8%), and nitrogen (7.0%). The developed briquettes showed a moisture content, volatile matter, ash, and fixed carbon in the range of 3.7 to 8.9%, 9.9 to 21.5%, 45.6 to 76.4%, and 8.2 to 22.8%, respectively. Their ultimate analysis results were: carbon (21.1%), hydrogen (1.3%), oxygen (1.8%), and nitrogen (1.9%). The briquette combustion properties revealed an ignition time, burning rate, and water boiling time of 5.35 seconds, 0.16 g/min, 31.1 minutes, respectively with higher and lower heating values of 14.87 and 7.88 MJ/kg, respectively. The briquette ash compounds were sodium 1718.5 ppm, potassium 20017.8 ppm, copper 6.12 ppm, cadmium 1.22 ppm, and lead 25.6 ppm. TGA/ DTG analysis indicated high mass loss rates at 105°C and maximum energy release between 600 and 900°C. The mechanical compressive strength was between 19 and 50 MPa, with bulk density between 1.82 and 2.02 g/cm3. Thus, the briquettes from the biogas digestate demonstrate potential for domestic thermal applications in Uganda.
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    A Comparative Analysis of Thermal Performance, Annual Energy Use, and Life Cycle Costs of Low-cost Houses Made with Mud Bricks and Earthbag Wall Systems in Sub-Saharan Africa
    (Energy and Built Environment., 2021) Wesonga, Racheal; Kasedde, Hillary; Kibwami, Nathan; Manga, Musa
    Given the high demand for low-cost housing by the low-income earners, coupled with the tropical climate experienced in sub-Saharan Africa, new-built housing stock needs utmost attention to cost, durability, and efficiency. With the walls accounting for a substantial proportion of the total building cost, choice of a wall system for use in building construction is critical. This choice usually depends on how durable, comfortable, ecological, and economical a given system is, to meet both the quality standards and low-cost aspects of housing. Although the earthbag building system allows for the construction of strong, affordable, and sustainable housing, it is not widely known. As such, its sustainable characteristics have gone unrecognised throughout the building industry. This paper examines and compares the thermal properties and total Life Cycle Costs (LCC) of earthbag walls with the commonly used burnt brick walls - based on the Degree-Days method and Life Cycle Costing analyses of building walls located in one of the hottest regions in Uganda. In-situ measurements of temperature and heat flux were conducted in accordance with ISO 9869 and the annual energy requirements obtained. The total LCC were calculated based on the initial construction costs and annual energy costs attributed to the building wall systems. Earthbags housing was found to be thermal-physically better than the brick wall with a lower U-value resulting in lower annual energy requirements and a huge saving in annual energy costs of up to 83.2%. This saving, coupled with low initial construction costs made the earthbag unit 68.7% cheaper than the burnt brick unit over a 30-year period. Therefore, this study findings suggest earthbag walling system as an economically viable and technically feasible low-cost construction option for rural areas and low-incomers earners’ housing in warm climatic conditions, a characteristic of sub-Saharan countries – so as to promote regional development.