Research Articles

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Browsing Research Articles by Author "Jjagwe, Joseph"

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    Development and appraisal of hand wash-wastewater treatment system for water recycling as a resilient response to COVID-19
    (Elsevier, 2021-07-28) Olupot, Peter Wilberforce; Menya, Emmanuel; Jjagwe, Joseph; Wakatuntu, Joel; Kavuma, Tonny; Wabwire, Andrew; Kavuma, Steven; Okodi Mcmondo, Samuel; Nabuuma, Betty; Mpagi Kalibbala, Herbert
    In this work, results from characterization of handwashing wastewater from selected stations in Kampala City, Uganda, revealed that handwashing wastewater did not meet permissible international standards for wastewater discharge to the environment. The ratio of BOD5 to COD of ˂ 0.5 implied that handwashing wastewater was not amenable to biological treatment processes. Turbidity of ˃ 50 NTU pointed to the need for a roughing filter prior to slow sand filtration. Subsequently, a handwashing wastewater treatment system consisting of selected particle sizes of silica sand, zeolite, and granular activated carbon as filtration and/or adsorption media was developed and assessed for performance towards amelioration of the physicochemical and biological parameters of the handwashing wastewater. Treated water from the developed wastewater treatment system exhibited turbidity of 5 NTU, true color of 10 Pt-Co, apparent color of 6 Pt-Co, and TSS of 9 mgL-1, translating to removal efficiencies of up to 98.5%, 98.1%, 99.7%, and 96.9%, respectively. The residual total coliforms and E. coli of 1395 and 1180 CFU(100 mL)-1 respectively, were totally eliminated upon disinfection with 0.5 mL NaOCl (3.5% wt/ vol) per liter of treated wastewater. The treated water was thus suitable for recycling for handwashing purposes as opposed to letting handwashing wastewater merely go down the drain. This approach provides a resilient response to COVID-19, where communities faced with water scarcity can treat and recycle handwashing wastewater at the point of washing. It thus enables more people to have the opportunity to practice handwashing, abating the high risks of infection, which could otherwise arise.
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    Optimization of pyrolysis conditions for production of rice husk-based bio-oil as an energy carrier
    (Elsevier, 2023-11-09) Wakatuntu, Joel; Olupot, Peter Wilberforce; Jjagwe, Joseph; Menya, Emmanuel; Okure, Mackay
    Bio-oil is an eco-friendly energy source with potential to substitute fossil-derived fuels. This study optimized pyrolysis conditions for production of bio-oil from rice husks. Response surface methodology based on central composite design was employed to maximize bio-oil yield and high heating value (HHV) while minimizing water and ash contents. The pyrolysis process conditions were; temperature (400–650 ◦C), heating rate (6000–9750 ◦Ch-1), and holding time (600–1800 s). Analysis of variance revealed that the linear model best fits the responses of bio-oil yield and water content. On the other hand, the quadratic model best fits the responses of HHV and ash content. Pyrolysis temperature had the greatest influence on each of the studied responses, followed by holding time and lastly heating rate. Optimum pyrolysis conditions were found to be; temperature (650 ◦C), heating rate (9750 ◦Ch-1), and holding time (1800 s), leading to bio-oil yield, HHV, water, and ash contents of 38.13%, 23.40 MJ/kg, 18.27%db, and 0.16%db, respectively. These results fall in the range of standard quality values for bio-oil in published literature where >15 MJ/kg, 20–30%, 0.15–0.25% are the recommended ranges for HHV, water, and ash contents, respectively. Results from the FTIR spectroscopy revealed that phenolic compounds contributed the most to bio-oil composition. Phenolic compounds positively influenced the quality of bio-oil due to their high calorific values. Gas chromatograph and mass spectrometry results showed peaks continuing to spill up to the maximum retention time indicating good thermal stability and bio-oil quality.
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    Optimization of roughing filtration unit for a handwashing wastewater recirculation point-of-use system
    (IWA PUBLISHING COMAPANY, 2022-11-22) Olupot, Peter Wilberforce; Menya, Emmanuel; Jjagwe, Joseph; Wakatuntu, Joel; Román, Franz; Hensel, Oliver
    A downward roughing filter unit consisting of silica sand as the filter medium was optimized for performance towards removal of turbidity and suspended solids from handwashing wastewater. Design-Expert software was employed to optimize media particle size, filter depth, and flow rate. Linear and quadratic models were found to best fit the responses of turbidity and suspended solids removal, respectively. Particle size and flow rate were the only parameters with significant effects on the removal of turbidity and suspended solids. Optimal conditions were found to be media particle size 0.6 mm, filter depth 12 cm, and flow rate 0.3 Lmin 1 , corresponding to removal efficiencies of 62 and 67% for turbidity and total suspended solids (TSS), respectively, as predicted by the model. Validation of the model at optimal conditions resulted in turbidity and TSS removal of 55 and 53%, respectively. Additionally, removal efficiencies of the roughing filter towards apparent colour, true colour, biochemical oxygen demand (BOD5), and chemical oxygen demand (COD) from handwashing wastewater were 56, 20,32, and 5%,respectively. Overall, although the turbidity of filtered water was .50 NTU, the reduction achieved by roughing filtration is a significant step in enhancing the performance of water treatment processes downstream, including filtration and adsorption by slow sand filters and activated carbon, respectively.
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    Progress in deployment of biomass-based activated carbon in point-of-use filters for removal of emerging contaminants from water: A review
    (Elsevier, 2023-03-01) Menya, Emmanuel; Jjagwe, Joseph; Mpagi Kalibbala, Herbert; Storz, Henning; Wilberforce Olupot, Peter
    Emerging contaminants (ECs) are increasingly being detected in drinking water, posing numerous public health concerns. Granular activated carbon (GAC) offers good prospects for removing ECs at point-of-use (POU), enabling households to have access to safe water. This paper reviews the current advances in the deployment of biomass-derived GACs (B-GACs) for the removal of ECs at POU. It highlights key sources, pathways, and impacts of ECs on public health. It also reveals preparation routes and performance aspects of B-GACs for POU water purification. Knowledge gaps on the subject matter were identified. The review revealed that shells of nuts, which are typically hard and of high density are the most investigated for valorisation into GAC for POU water purification. To encourage the wide application of B-GACs for POU water purification, there is a need to tailor available soft, low-density biomass wastes and suit them as GAC precursors for the removal of ECs at the point of use. Future studies need to focus on tailoring the production of B-GACs for the removal of specific ECs from water. Additional future research insights include the identification of re-generation options for B-GACs, options for removal of residual nanoparticles from the filtrate, lifecycle analysis, and costing of various GAC-based POU water filters.
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    Synthesis and Application of Granular Activated Carbon from Biomass Waste Materials for Water Treatment :
    (Keai publishing, 2021-04-06) Jjagwe, Joseph; Olupot, Peter Wilberforce; Menya, Emmanuel; Mpagi Kalibbala, Herbert
    There is an increased global demand for activated carbon (AC) in the application of water treatment and purification. Water pollutants that have exhibited a greater removal efficiency by AC included but are not limited to heavy metals, pharmaceuticals, pesticides, natural organic matter, disinfection by-products, and microplastics. Granular activated carbon (GAC) is mostly used in aqueous solutions and adsorption columns for water treatment. Commercial AC is not only costly but also obtained from non-renewable sources. This has prompted the search for alternative renewable materials for AC production. Biomass wastes present a great potential for such materials because of their availability and carbonaceous nature. This, in turn, can reduce the adverse environmental effects caused by poor disposal of these wastes. The challenges associated with biomass waste-based GAC are their low strength and attrition resistance which make them easily disintegrate under the aqueous phase. This paper provides a comprehensive review of recent advances in the production of biomass waste-based GAC for water treatment and highlights future research directions. Production parameters such as granulation conditions, use of binders, carbonization, activation methods and their effect on textural properties are discussed. Factors influencing the adsorption capacities of the derived GACs, adsorption models, adsorption mechanisms, and their regeneration potentials are reviewed. The literature reveals that biomass waste materials can produce GAC for use in water treatment with the possibility of being regenerated. Nonetheless, there is a need to explore 1) the effect of preparation pathways on the adsorptive properties of biomass-derived GAC, 2) sustainable production of biomass-derived GAC based on life cycle assessment and techno-economic analysis, and 3) adsorption mechanisms of GAC for removal of contaminants of emerging concerns such as microplastics and unregulated disinfection by-products.