Gulu University Digital Repository (GU-IR)
GU-IR preserves research output from the Gulu University community
Communities in GU-IR
Select a community to browse its collections.
Recent Submissions
Optimization of pyrolysis conditions for char production from rice husks and its characterization as a precursor for production of activated carbon
(Springer, 2019-03-13) Menya, E.; Olupot, P. W.; Storz, H.; Lubwama, M.; Kiros, Y.; John, M. J.
Response surface methodology was employed to optimize pyrolysis conditions for production of char with maximum yield, fixed carbon content, and with minimum ash content from Uganda’s New Rice for Africa (NERICA) 1 rice husk variety. The aim was to obtain rice husk char with more suitable properties as an activated carbon precursor. Mathematical models were developed to explain the relationships between the experimental responses and the pyrolysis parameters of temperature (400–600 °C), heating rate (10–25 °C min−1), and heating period (60–120 min). The optimized rice husk char was further characterized for elemental and proximate compositions, thermal behavior, specific surface area, as well as surface functional groups. Results from the analysis of variance (ANOVA) revealed that the quadratic model best fits each of the responses. Pyrolysis temperature had the greatest influence on each of the responses, followed by heating period, and lastly heating rate. Optimum pyrolysis conditions were found to be temperature (406 °C), heating rate (10 °C min−1), and heating period (60 min), resulting in char yield, fixed carbon, and ash contents of 35.26, 55.39, and 35.01% dry basis, respectively. Compared to raw rice husk, the resulting rice husk char was found more suited as activated carbon precursor, due to its enriched carbon content (60.35%) and specific surface area (123.9 m2 g−1). Thermogravimetric analysis of the rice husk char revealed that thermal activation temperatures higher than 400 °C may be required to considerably devolatilize the char, forming a more porous activated carbon.
Synthesis and evaluation of activated carbon from rice husks for removal of humic acid from water
(Springer, 2020-11-26) Menya, E.; Olupot, P. W.; Storz, H.; Lubwama, M.; Kiros, Y.
Activated carbon was synthesized from the New Rice for Africa (NERICA) rice husk variety, followed by its evaluation for removal of humic acid from water. Product values of carbon yield, C and total specific surface area, as,BET were employed as the performance criterion. The best physically activated carbon resulted from char activation at 800 °C for 10 min, leading to as,BET and C×as,BET values of 756.8 and 402.7 m2 g−1, respectively. The best chemically activated carbon resulted from 30 wt% H3PO4 activation of rice husk at 400 °C for 30 min, leading to as,BET and C×as,BET values of 2258.4 and 1058.7 m2 g−1, respectively. Despite the higher as,BET value, the maximum adsorption capacity of the best chemically activated carbon (5.3 mg g−1) was found lower than 8.9 and 27.2 mg g−1 exhibited by the chemically activated carbons prepared at 500 and 600 °C, respectively. The best adsorption conditions included carbon dose of 0.5 g, solution pH of 2, and contact time of 60 min. The adsorption capacity of the prepared activated carbons (27.2 mg g−1) was comparable to that of the commercial activated carbon (30.40 mg g−1). The analyses of the adsorption isotherms and kinetics revealed that the experimental data fits well the Langmuir isotherm model, as well as the pseudo-second-order kinetic model. The latter suggests that the adsorption of humic acid onto the activated carbon was controlled by the chemisorption process. Overall, the study revealed that the NERICA rice husk variety has good prospects for preparation of activated carbons for humic acid adsorption.
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; Kalibbala, Herbert Mpagi; Storz, Henning; Olupot, Peter Wilberforce
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 deployment of biomass-derived GACs (B-GACs) for 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 valorization into GAC for POU water purification. To encourage wide application of B-GACs for POU water purification, there is need to tailor available soft, low-density biomass wastes and suit them as GAC precursors for removal of ECs at the point of use. Future studies need to focus on tailoring the production of B-GACs for removal of specific ECs from water. Additional future research insights include identification of regeneration options for B-GACs, options for removal of residual nanoparticles from the filtrate, lifecycle analysis and costing of various GAC-based POU water filters.
Biogas as an alternative to fuelwood for a household in Uleppi sub-county in Uganda
(Agric Eng Int: CIGR Journal, 2013-01-24) Menya, E.; Alokore, Y.; Ebangu, B. O.
Over 93% of Uganda’s population relys on wood fuel in form of either charcoal or fuelwood for cooking. Uleppi sub-county in Arua district is a typical example of such areas in Uganda where households entirely use fuelwood to meet their energy demand for cooking. The use of fuelwood is however associated with the use of inefficient stoves that accelerate deforestation thus increasing carbon dioxide (CO2) emissions. The use of fuelwood is also associated with a smoky environment that has adverse health impacts on women and children who spend long hours in the kitchen. In addition, women and children spend long hours gathering fuelwood which significantly reduces farm productivity. This project was therefore aimed at design and construction of a biogas plant ideal for a household in Uleppi sub-county as an alternative to fuel wood. The research involved sizing of the floating drum biogas digester and gasholder, economic analysis as well as estimating CO2 emission reduction. For a household with an average of three heads of cattle managed in a free range system, the biogas digester and gasholder were sized as 1.4 m3 and 0.29 m3 respectively with 0.48 m3 of biogas produced per day. At this capacity, it was found that biogas utilization can reduce individual household consumption of wood fuel by 66.32% for a household size of five persons. The carbon emission reduction for all households was estimated at 432 tons of CO2 per year.
The benefit-cost ratio was found to be 3.26, hence worthy to invest in the biogas technology. The capital recovery period for 459 USD of the biogas plant installation with an economic life of 15 years at 23 % interest rate was found to be two years.
Managing Together: Forms of Stakeholder Participation in Technical and Vocational Training Institutions in Gulu City, Uganda
(East African Journal of Education Studies, 2026-06-02) Latim, Ongom Gaudence; Lamaro, Gloria
This study examined the forms of stakeholder participation in the management of Technical and Vocational Training Institutions (TVETs) in Gulu City, Uganda. The study was motivated by the growing recognition that stakeholder engagement improves institutional governance, accountability, and student enrolment outcomes. A mixed-methods approach was adopted using a cross-sectional design. Data were collected from instructors, principals, Board of Governors (BoG), Parents and Teachers Association (PTA) executives, and education officials using questionnaires, interviews, and document analysis. Quantitative data were analysed using descriptive statistics, while qualitative data were analysed thematically. Findings revealed that stakeholders participate in monitoring teaching and learning, attending meetings, budgeting, coordinating school activities, and supporting institutional planning. The study further found that stakeholder participation positively influences institutional effectiveness and student enrolment levels. However, challenges such as limited parental financial contribution and inconsistent participation were observed. The study concludes that structured and active stakeholder engagement is essential for strengthening TVET governance. It recommends enhanced collaboration frameworks between institutions and stakeholders to improve accountability and enrolment outcomes.