Browsing by Author "Menya, Emmanuel"

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    Development and appraisal of handwash-wastewater treatment system for water recycling as a resilient response to COVID-19
    (Journal of Environmental Chemical Engineering, 2021) Olupot, Peter W.; Menya, Emmanuel; Jjagwe, Joseph; Wakatuntu, Joel; Kavuma, Tonny; Wabwire, Andrew; Kavuma, Steven; Okodi, Samuel M.; 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 a 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 purpose 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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    Effects of sawdust and adhesive type on the properties of rice husk particleboards
    (Results in Engineering, 2022) Olupot, Peter Wilberforce; Menya, Emmanuel; Lubwama, Festo; Ssekaluvu, Lawrence; Nabuuma, Betty; Wakatuntu, Joel
    This study set out to investigate the effects of adhesive type, rice husk and sawdust proportions on the properties of composite particleboards. Specimens of 200 × 200 × 24 mm were made by blending 500 g of rice husks with each adhesive type at a mass ratio of 1:1. The rest of the specimens of similar dimensions were prepared with addition of sawdust in the range of 10–40 wt%, while maintaining the ratio of biomass particles to adhesive at 1:1. Three commercial synthetic adhesives Fevicol (FV), Ponal (PA) and woodfix (WF) were used. The particleadhesive mixtures were molded into a mat which was subsequently cold pressed at 10 MPa and left to dry in air. Density, water absorption (WA), linear expansion (LE), thickness swelling (TS), modulus of elasticity (MOE), modulus of rupture (MOR) and screw holding capacity of the specimens were evaluated. Adhesives were found to have over 42% solid content, with similar liquid constituents but in varying proportions. FTIR library search for the spectra of FV, PA and WF revealed correlations of 82.5%, 78.6% and 50.2%, respectively with polyvinylacetate. The developed boards had density 510–610 kg/m3, MOE 13–26 MPa, TS 9–31%, LE 3–7%. These properties suit them for furniture boards and sound proofing. The properties improved with increasing proportion of sawdust. FV and PA-bonded particleboards exhibited higher stability and strengths than WF-bonded particleboards due to higher concentrations of polyvinyl-acetate in the latter. Blending 40 wt% sawdust, 10 wt% rice husk with 50 wt% of either FV or PA showed better prospects.
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    Factors affecting adoption of mulching in Kibaale sub-catchment, South Central Uganda
    (Int. J. Sustainable Agricultural Management and Informatics, 2016) Kakaire, Joel; Mensah, Albert K.; Menya, Emmanuel
    Mulching is one of the major soil and water conservation measures applied for conserving soil moisture and modifying soil physical environment. The study aimed at determining the factors which influence the adoption of mulching in Kibaale sub-catchment, Uganda. 100 structured questionnaires; key informant interviews and observation were used to obtain the socio economic and institutional data. To determine the factors affecting adoption of mulching, descriptive statistics and factor analysis were used. Chi-square (P ≤ 05) was used to establish the relationship between the identified factors and adoption. Using chi-square test, the study also identified Education level of household head, household size, accessibility to farmland and marital status as the major factors that significantly affected adoption of mulching. The community leaders should ensure that the members attain some level of education and ensure that the land owned by individuals is within their periphery of management and control.
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    Optimization of roughing filtration unit for a handwashing wastewater recirculation point-of-use system
    (Water Science & Technology, 2022) Olupot, Peter Wilberforce; Menya, Emmanuel; Jjagwe, Joseph; Wakatuntu, Joel; Románc, 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 flowrate. 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 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 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 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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    Synthesis and application of Granular activated carbon from biomass waste materials for water treatment: A review
    (Journal of Bioresources and Bioproducts, 2021) Jjagwe, Joseph; Olupot, Peter W.; Menya, Emmanuel; Mpagi Kalibbala, Herbert
    There is an increased global demand for activated carbon (AC) in application of water treatment and purification. Water pollutants that have exhibited a greater removal efficiency by AC included but not limited to heavy metals, pharmaceuticals, pesticides, natural organic matter, disinfection by-products, and microplastics. Granular activated carbon (GAC) is mostly used in aqueous so- lutions 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 of such materials because of their availability and carbonaceous nature. This in turn can reduce on the adverse environmen- tal 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 aqueous phase. This paper provides a comprehensive review on recent advances in produc- tion 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 regener- ation potentials are reviewed. The literature reveals that biomass waste materials can produce GAC for use in water treatment with possibilities of being regenerated. Nonetheless, there is a need to explore 1) the effect of preparation pathways on the adsorptive properties of biomass de- rived 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.
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    Techno-economic assessment of municipal solid waste gasification for electricity generation: a case study of Kampala City, Uganda
    (CIGR Journal, 2015) Kivumbi, Bernard; Olwa, Joseph; Martin, Andrew; Menya, Emmanuel
    This study was aimed at assessing the techno-economic potential of municipal solid waste (MSW) generated in Kampala City for electricity production through gasification. The quantity, characteristics and gasification parameters were determined. In addition, the gasifier- engine system components were sized, and an economic analysis was conducted to obtain the net present value (NPV) and the payback period. This study found that 523 t/d of MSW is collected in Kampala City. The biomass component of MSW was found to be 459.5 t/d with moisture content of 71.09% on as-received basis. The physical characteristics of the gasified biomass included 11.8% moisture content, 88.2% total solids, 25.9% ash content and 57.7 kg/m3 bulk density. The resulting normalized producer gas constituted 11.64% H2, 13.70% CO, 16.09% CO2, 54.12% N2, 4.45% CH4 and lower heating value (LHV) of 4.75 MJ/Nm3. The design fuel flow rate of 0.23 kg/s, specific gasification rate (SGR) of 5089.29 kg h-1 m-2 and specific energy demand of 42.75 GJ m-2 h-1 were obtained. This yields a net electrical power output of 425.17 kW with an overall efficiency of 15.6%. The net annual electricity generation from a single gasifier-engine system was found to be 2.97 GWh/a. The economic analysis for this system worth $887 333 of investment cost yielded a payback period of 6.57 years while the NPV at 6% interest rate was found to be nine years with a value of $316 47.
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    Variability and Changes in Climate in Northern Uganda
    (East African Nature and Science Organization, 2024-03-18) Oriangi, George; Mukwaya, Paul Isolo; Luwa, Justine Kilama; Menya, Emmanuel; Malinga, Geoffrey Maxwell; Bamutaze, Yazidhi
    Variability and changes in climate are generally expected to occur. However, there remain gaps on dynamics of expected regional variations in climatic changes. This study assessed historic and projected climatic conditions up to the year 2033. The study hypothesized that temperature rather than rainfall significantly increased for the period 1980-2010 and rainfall rather than temperature is likely to decrease significantly by 2033 for Gulu District in northern Uganda. To determine historic climatic trends, rainfall and temperature data were obtained from Uganda National Meteorological Authority (UNMA) while for future climate, the PRECIS (Providing Regional Climates for Impact Studies) modelled data based on projected conditions at a 50 km spatial resolution was used. These data sets were subjected to trend analysis and the differences in means were detected at a 95% confidence level. Contrary to the evidences from other empirical studies, results generally indicated decreasing rainfall for the period 1980-2010. However, the decrease was not significant (P > 0.05) while both historic mean annual maximum and minimum temperature trends showed a statistically significant increase (P<0.05). Projections for 2033 reveal a significant decrease in rainfall (P < 0.05) while both maximum and minimum temperature will remain quasi uniform