NRU :: Browsing by Author "Zziwa, Ahamada"

Browsing by Author "Zziwa, Ahamada"

Now showing 1 - 20 of 20

Assessing soil erosion risk in a peri‑urban catchment of the Lake Victoria basin
(Modeling Earth Systems and Environment, 2022) Ssewankambo, Gyaviira; Kabenge, Isa; Nakawuka, Prossie; Wanyama, Joshua; Zziwa, Ahamada; Bamutaze, Yazidhi; Gwapedza, David; Tally Palmer, Carolyn; Tanner, Jane; Mantel, Sukhmani; Tessema, Bezaye
Soil erosion and sedimentation contribute to deteriorating water quality, adverse alterations in basin hydrology and overall ecosystem biogeochemistry. Thus, understanding soil erosion patterns in catchments is critical for conservation planning. This study was conducted in a peri-urban Inner Murchison Bay (IMB) catchment on the northern shores of Lake Victoria since most soil erosion studies in Sub-Saharan Africa have been focused on rural landscapes. The study sought to identify sediment sources by mapping erosion hotspots using the revised universal soil loss equation (RUSLE) model in appendage with field walks. RUSLE model was built in ArcGIS 10.5 software with factors including: rainfall erosivity, soil erodibility, slope length and steepness, land cover and support practices. The model was run, producing an erosion risk map and field assessments conducted to ground-truth findings and identify other hotspots. The percentage areas for RUSLE modelled erosion rates were: 66.8% for 0–2 t ha− 1 year− 1; 10.8% for 2–5 t ha− 1 year− 1; 10.1% for 5–10 t ha− 1 year− 1; 9% for 10–50 t ha− 1 year− 1 and 3.3% for 50–100 t ha− 1 year− 1. Average erosion risk was 7 t ha− 1 year− 1 and the total watershed erosion risk was 197,400 t year− 1, with croplands and steep areas (slope factor > 20) as the major hotspots (> 5 t ha− 1 year− 1). Field walks revealed exposed soils, marrum (gravel) roads and unlined drainage channels as other sediment sources. This study provided the first assessment of erosion risk in this peri-urban catchment, to serve as a basis for identifying mitigation priorities. It is recommended that tailored soil and water conservation measures be integrated into physical planning, focusing on identified non-conventional hotspots to ameliorate sediment pollution in Lake Victoria.
Assessment of Municipal Organic Solid Waste, as a Potential Feedstock for Briquette Production in Kampala, Uganda
(Uganda. Journal of Sustainable Bioenergy Systems, 2020) Abondio, Richard B.; Komakech, Allan J.; Kambugu, Robert K.; Kiggundu, Nicholas; Wanyama, Joshua; Zziwa, Ahamada; Kyamanywa, Samuel
The current shortage of energy resources coupled with environmental degradation problems resulting from deforestation in Uganda has contributed to increased demand for renewable energy resources including municipal organic solid waste and agricultural residues. However, organic waste from Municipal Solid Waste (MSW) may contain contaminants that are harmful to public health and the environment. This study determined the heavy metal concentration in MSW in Kampala City, Uganda. Also, the physicochemical properties of briquettes produced from the MSW were compared with charcoal. The waste samples were collected from residential, institutional and market areas over a period of two weeks. They were then analyzed for the presence of heavy metals. Briquettes were made from the bio-waste and were subjected to calorific and proximate analysis. Results indicated that the mean concentrations of Cd, Cr, Cu, Fe, and Pb were 1.25 mg/kg, 2.04 mg/kg, 38.2 mg/kg, 3.97 mg/kg and 1.99 mg/kg respectively while Hg was not detected. The calorific values of briquettes ranged from 8.9 to 15.3 MJ/kg and were lower than those of charcoal. Heavy metal concentrations in bio-waste collected were below the permissible acceptable limits. These findings indicate that the sampled MSW does not pose a health hazard arising from the presence of such heavy metals and therefore could be a safe source of renewable energy
Assessment of the suitability of pineapple waste as feedstock for vermicomposting
(Agricultural Engineering International CIGR Journal, 2021) Miito, Gilbert; Komakech, Allan; Zziwa, Ahamada; Kiggundu, Nicholas; Kambugu, Robert
Declining soil fertility is a challenge to sustainable agricultural production in sub-Saharan Africa. However, large volumes of agricultural waste are generated from pineapples that could be converted into soil conditioners through vermicomposting utilizing earthworms. Several types of agricultural waste have been studied extensively as vermicompost feedstock, but little work exists on pineapple waste. The objective of this study was to investigate the suitability of pineapple waste as feedstock for vermicomposting. We assessed the physicochemical properties of fresh, pre-composted pineapple waste and the resultant vermicompost. We also studied the optimal feeding rate and stocking density of the system. The study revealed that pre-composting reduced the moisture content (29%), volatile organic carbon (VOC) (10%), and increased the pH (57%), which was helpful in waste stabilization as well as in the mass reduction of the waste. Vermicomposting after pre- composting increased the bulk density (92%), ash content (25.4%), pH (10%), EC (14%), total phosphorus (21%), and total potassium (28%). The technology also decreased the moisture content (1%), VOC (12%), total organic carbon (81%), total nitrogen (22%), and the carbon to nitrogen ratio (76.4%) of the pineapple waste hence yielding a more stabilized and mineralized vermicompost. The study further revealed an optimal feeding rate of 2 kg feeds/kg worms and a stocking density of 1 kg worms m-2 for total nitrogen and phosphorus mineralization of the pineapple waste. The degradation of the pineapple waste by earthworms demonstrated the practicability of vermicomposting as a low-cost and straightforward technology of converting pineapple waste into a nutrient-rich soil amendment.
Characterization of Banana Peels Wastes as Potential Slow Pyrolysis Feedstock
(Journal of Sustainable Development, 2018) Kabenge, Isa; Omulo, Godfrey; Banadda, Noble; Seay, Jeffrey; Zziwa, Ahamada; Kiggundu, Nicholas
Uganda is the world’s second largest producer and consumer of banana after India. This has resulted into vast quantities of banana wastes, including the leaves, pseudostem, stalks, rejected and rotten fruits and the fruit peels. This study focuses on the characterization of banana peels to yield banana peels vinegar (BPV), tar and biochar as value added products that can be useful to farmers. Dried banana peels were characterized via proximate, ultimate, lignocellulosic, thermogravimetric (TG), and calorific value analyses. The obtained results showed that the volatile matter and fixed carbon contents were 88.02% and 2.70% while carbon, nitrogen and sulphur were 35.65%, 1.94% and 20.75 ppm respectively. The hemicellulose, cellulose and lignin contents were 41.38%, 9.90% and 8.90% while the higher and lower heating values were 16.15 MJ/kg and 14.80 MJ/kg. The maximum devolatilization rate in the banana peel biomass occurred in the temperatures range of 450–550oC which was taken as the slow pyrolysis regime temperature. The high levels of fixed carbon, volatile matter and ash contents were strong indicators that banana wastes are adequate feedstock for pyrolysis work to yield bio-infrastructure products. Similarly, the lignin, cellulose and hemicellulose fractions had significant correlation between the biomass heating values and the eventual chemical compounds present BPV and biochar. The characterization properties of the banana peels are akin to the leaves and pseudostem and thus are suitable for pyrolysis process.
Characterization of Slow Pyrolysis Wood Vinegar and Tar from Banana Wastes Biomass as Potential Organic Pesticides
(Journal of Sustainable development, 2017) Omulo, Godfrey; Willett, Sarah; Seay, Jeffrey; Banadda, Noble; Kabenge, Isa; Zziwa, Ahamada; Kiggundu, Nicholas
Slow pyrolysis process has been used in the recent past to yield wood vinegar from various biomass wastes with a quest to investigate their chemical composition and possible uses. This study utilizes the abundant banana wastes in Uganda including leaves, pseudostem and peels (mpologoma, kisansa and kibuzi species) in the slow pyrolysis process to yield vinegar, tar and biochar. Characterization of these banana wastes’ vinegar and tar fractions were investigated via chromatographic and physicochemical analysis. The principle compounds present in the banana wastes vinegar and tar as per percentage peak areas were acids (68.6%), alcohols (62.5%), ketones (27.6%), phenols (25.7%) and furans (21.8%). The products characterization indicate that vinegar and tar contain compounds that can be used as pesticides, termiticide, fungicides, insect repellants, anti-leaching and soil degradation agents. Thus wood vinegar and tar can have sustainable impacts on agricultural sectors and chemical industries especially for developing countries.
Climate trends, risks and coping strategies in smallholder farming systems in Uganda
(Climate Risk Management, 2018) Mubiru, Drake N.; Radeny, Maren; Kyazze, Florence B.; Zziwa, Ahamada; Lwasa, James; Kinyangi, James; Mungai, Catherine
Smallholder farmers in Uganda face a wide range of agricultural production risks. Climate change and variability present new risks and vulnerabilities. Climate related risks such as prolonged dry seasons are becoming more frequent and intense with negative impacts on agricultural livelihoods and food security. This paper examines farmers’ perceptions of climate change, climate-related risks affecting crop and livestock production, including climate-risk management and adaptation strategies. Drought, increasing disease and pest incidences, decreasing water sources, lack of pasture, bush fires, hailstorms, changes in crop flowering and fruiting times were the major climate-related risks reported. In order to cope with climate change and climate variability, farmers use a wide range of agricultural technologies and strategies. Mulching, intercropping and planting of food security crops were among the most commonly used practices. Other strategies included water harvesting (mainly for domestic consumption), other soil and water conservation technologies and on-farm diversification. Farmers often use a combination of these technologies and practices to enhance agricultural productivity. Average maximum temperatures increased across the two sites. Trends in average annual rainfall showed mixed results, where a general decline was observed in one district and a relatively stable trend in the other district. Perceived changes in climate included erratic rainfall onset and cessation (which were either early or late), poor seasonal distribution of rainfall and little rainfall. In addition, farmers reported variations in temperatures. Farmers’ perception of changing rainfall characteristics and increasing temperatures were consistent with observed historical climatic trends based on meteorological data.
Contextual investigation of factors affecting sludge accumulation rates in lined pit latrines within Kampala slum areas, Uganda
(Water SA, 2016) Zziwa, Ahamada; Lugali, Yvonne; Wanyama, Joshua; Banadda, Noble; Kabenge, Isa; Kambugu, Robert; Kyazze, Florence; Kigozi, Julia B.; Tumutegyereize, Peter
Pit latrines in slums areas of Uganda fill up faster than might be expected from some estimates owing to inappropriate use and failure to consider critical factors affecting sludge accumulation rates at the planning, design and construction stages. This study sought to investigate factors affecting filling rates of lined pit latrines in slum areas of Kampala with the goal of contributing to accurate planning, design, construction, emptying and overall maintenance. Fifty-five pit latrines were selected from the five divisions of Kampala city using stratified random sampling. Data collected included: number of users, frequency of emptying, years taken since last emptying, type of non-faecal materials deposited, cross-sectional dimensions of the pit, rate of sludge degradation and geo-physical factors of pit location. Methods used were: field surveys, questionnaires and key informant interviews plus on-site depth measurement. Mass loss tests to investigate the rate of sludge degradation were carried out in the laboratory at moisture content levels similar to those in pit latrines. Sludge accumulation rates were calculated using volume of sludge in the pit, number of users and time taken since last emptying. Statistical analyses included correlation and one-way ANOVA. Results revealed that number of users and type of material deposited in the pit latrines, especially non-faecal matter, had a significant (p < 0.05) effect on sludge accumulation rate. Public pit latrines with a higher number of users had lower sludge accumulation rates and this was attributed to greater degradation taking place and greater restriction on entry of non-faecal matter. The rate of sludge degradation was higher at 90–100% than 80–90% moisture content, due to better degradation conditions. Tighter restrictions on non-faecal material deposition into pit latrines are recommended to reduce filling rates of pit latrines in slum areas.
A critical analysis of physiochemical properties influencing pit latrine emptying and feacal sludge disposal in Kampala Slums, Uganda
(African Journal of Environmental Science and Technology, 2016) Zziwa, Ahamada; Nabulime, Maureen N.; Kiggundu, Nicholas; Kambugu, Robert; Katimbo, Abia; Komakech, Allan J.
Inadequate information on physiochemical properties of faecal sludge leads to inappropriate design of pit emptying devices and poor faecal sludge disposal contributing to environmental pollution. This study undertook a critical analysis of physiochemical properties of feacal sludge that influence design and performance of pit emptying devices and faecal sludge disposal for improved faecal sludge management in urban slums. The physiochemical properties determined were; Moisture content (MC), ash content (AC), total solids (TS), volatile solids (VS), nitrogen (N), phosphorous (P), potassium (K) and pH. Samples were collected from 55 unlined pits at depths of 0, 0.5, 1 and 1.5 m from pit surface. The unlined pits in this study were purposively selected from slums in Kampala. A sample of 300 g was sucked from each depth using a manual sampling tool and emptied into a plastic container. The container was then wrapped in a black plastic bag and transported in cooler boxes to the lab for analysis. The properties were subjected to Principal Component Analysis to isolate the critical parameters that affect pit emptying and faecal sludge disposal. The mean results were: MC of 86 ± 8.37%; TS of 0.14 ± 0.08 g/g wet sample; VS of 0.73 ± 0.32 g/g dry sample; pH of 8.0 ± 1.5; AC of 0.35± 0.18 g/g dry sample; TN of 3.5 ± 0.08%; K of 2.2± 0.13% and P of 1.4± 0.05%. It was concluded that physiochemical properties in Ugandan pits are comparable to those of global pits except for the acidic conditions at top surface in some pits, and higher moisture content in pits due to the high water table. PCA results showed that moisture content and total solids affected pit emptying techniques while fractional content of N, P and pH affect most choice of faecal sludge disposal technique.
Inferring Strength Of Structural Timbers From Small Clear Specimen Strength Test Data
(International Journal of Research in Engineering & Advanced Technology, 2016) Zziwa, Ahamada; Naku Ziraba, Yasin; Mwakali, Jackson A.
Despite the existence of diverse timber species in least developed countries such as Uganda, wood has been underutilized in the construction sector on grounds of its perceived unreliability due to lack of adequate strength data. Attempts have been made to establish strength of small clear specimens but the relationship between MOE and MOR of small clear specimens and structural size tropical timber is not documented. Therefore this research was conducted to compare the flexural strength of small clear to that of structural size specimens; and particularly the effect of knots on MOE and MOR of structural size timber. Small clear tests were conducted in bending, compression and shear parallel to grain using standard procedures of the American Society for Testing and Materials (ASTM), ISO 8905 (1988), and BS 373 (1957). Structural size bending tests were conducted following ASTM ISO 8905 (1988), AS/NZS 2878 (2000); BS 4978; ASTM D198-02; ISO/FDIS 13910:2004 and BS 373 (1957). It was concluded that structural size MOE and MOR can be estimated from small clear MOE and MOR using reduction factors of 40% and 20% respectively. It was recommended that more research into the effect of complex knots, cross-grain and grain angle on timber strength be done for better structural grading of timber.
Irrigation Development in Uganda: Constraints, Lessons Learned, and Future Perspectives
(Journal of Irrigation and Drainage Engineering, 2017) Wanyama, Joshua; Ssegane, Herbert; Kisekka, Isaya; Komakech, Allan John; Banadda, Noble; Zziwa, Ahamada; Ebong, Tobias Oker; Mutumba, Charles; Kiggundu, Nicholas; Kayizi, Ronald Kato; Mucunguzi, Dominic Banaga; Kiyimba, Florence Lubwama
Policy makers in sub-Saharan African (SSA) countries have identified irrigation as a key ingredient to boosting food security and income as well as a precursor for agricultural development. However, most SSA countries have hardly exploited their irrigation potential. The overarching aim of this paper is to critically examine factors constraining exploitation of irrigation potential in Uganda. Lessons learned from previous interventions and successes elsewhere from countries comparable to Uganda are drawn and future perspectives to guide effective irrigation planning and development are recommended. From this paper, it is evident that there is no single blanket solution to constraints of irrigation development in SSA. All strategies should be implemented in a holistic manner dictated by specific local conditions. The key to successful adoption of irrigation lies in building the national irrigation capacity, improving access to reliable water for irrigation in proximity of the farms, streamlining extension services for farmers, addressing economic aspects of irrigation, and streamlining land tenure systems and management. It is recommended to operationalize government policy on irrigation by developing national guidelines on irrigated agriculture.
Modeling sludge accumulation rates in lined pit latrines in slum areas of Kampala City, Uganda
(African Journal of Environmental Science and Technology, 2016) Lugali, Yvonne; Zziwa, Ahamada; Banadda, Noble; Wanyama, Joshua; Kabenge, Isa; Kambugu, Robert; Tumutegyereize, Peter
Disposal of faecal sludge particularly in slum areas is a difficult undertaking given the lack of space and resources. Inaccurate prediction of sludge accumulation rates (SAR) in pit latrines leads to unplanned pit latrine emptying. Given that the users and owners cannot afford the conventional emptying techniques frequently, inappropriate methods such as open defecation and emptying into storm drainages are employed which consequently contribute to environmental and health-related challenges. The main objective of this study was to develop a predictive model for sludge accumulation rates in lined pit latrines in slum areas of Kampala so as to guide routine management of pit latrines. This mathematical model was developed using a mass balance approach with a sample space of 55 lined pits. The developed model gave an average sludge accumulation rate of 81±25 litres/person/year with an efficiency of 0.52 and adjusted R2 value of 0.50. The model was found to be sufficient and most suited for rental and public pit latrines given their bigger percentage in the slums. Further studies should include geo-physical characterization of soil and drainage of pit latrine sites so as to improve model accuracy.
Modeling Sludge Accumulation Rates in Lined Pit Latrines in Slum Areas of Kampala City, Uganda
(African Journal of Environmental Science and Technology, 2016) Lugali, Yvonne; Zziwa, Ahamada; Banadda, Noble; Wanyama, Joshua; Kabenge, Isa; Kambugu, Robert; Peter Tumutegyereize
Disposal of faecal sludge particularly in slum areas is a difficult undertaking given the lack of space and resources. Inaccurate prediction of sludge accumulation rates (SAR) in pit latrines leads to unplanned pit latrine emptying. Given that the users and owners cannot afford the conventional emptying techniques frequently, inappropriate methods such as open defecation and emptying into storm drainages are employed which consequently contribute to environmental and health-related challenges. The main objective of this study was to develop a predictive model for sludge accumulation rates in lined pit latrines in slum areas of Kampala so as to guide routine management of pit latrines. This mathematical model was developed using a mass balance approach with a sample space of 55 lined pits. The developed model gave an average sludge accumulation rate of 81±25 litres/person/year with an efficiency of 0.52 and adjusted R2 value of 0.50. The model was found to be sufficient and most suited for rental and public pit latrines given their bigger percentage in the slums. Further studies should include geo-physical characterization of soil and drainage of pit latrine sites so as to improve model accuracy.
Nutrient recovery from pineapple waste through controlled batch and continuous vermicomposting systems
(Journal of Environmental Management, 2021) Zziwa, Ahamada; Jjagwe, Joseph; Kizito, Simon; Kabenge, Isa; Komakech, Allan John; Kayondo, Henry
The largest portion of pineapple peels and pulp generated from production points is disposed of haphazardly contributing to a number of environmental and health challenges. However, these wastes contain valuable plant nutrients that could be recovered to boost soil fertility, and increase agricultural production. This study evaluated the variation in physico-chemical parameters in batch and continuous vermicomposting systems as potential pathways for nutrient recovery from pineapple waste. The study compared the efficiency of waste reduction and nutrient recovery for batch (B), and continuous (C) vermicomposting systems during a 60-day period. The substrates were pineapple peels (PW), and cattle manure (CM) fed in a ratio of 4:1 (w/w). Control reactors were fed with 100% CM in both the feeding modes. Results indicated that waste degradation was 60%, and 54% while earthworm biomass increased by 57% and 129% for BPW, and CPW, respectively. pH significantly decreased with time in both systems. Total phosphorous increased with vermicomposting time with that of B being significantly higher than C systems. Nitrogen, potassium, and sodium significantly increased in the control experiments while the three elements significantly reduced for BPW, and CPW owing to high leachate production in the latter. The N, P, K, and C retention in vermicompost was 24.2%, 90.4%, 67.5%, 41.1%, and 32.6%, 91.2%, 79.3%, 46.1%, for BPW and CPW, respectively. Continuous systems produced higher earthworm biomass and retained more nutrients in vermicompost than batch systems, and can therefore, be recommended as better systems for pineapple waste vermicomposting.
Occurrence and survival of pathogens at different sludge depths in unlined pit latrines in Kampala slums
(Water Sa, 2017) Nabateesa, Sylivia; Zziwa, Ahamada; Kabenge, Isa; Kambugu, Robert; Wanyama, Joshua; Komakech, Allan John
Occurrence and survival of pathogens in faecal sludge was investigated in unlined pit latrines at varying depths in peri-urban areas of Kampala city, Uganda. A total of 55 unlined pit latrines, 7 private and 8 rental unlined pit latrines were sampled in the first and second phases (representing the rainy season) and 40 pits in the third phase (representing dry season), and analysed for indicator organisms and pathogens from 4 pit latrine sludge layers, at depths of 0, 0.5, 1.0 and 1.5 m, following APHA standard methods. Physico-chemical parameters of the faecal sludge were also measured. Three sampling phases were undertaken to determine the effect of seasonal variation. Results indicate that the mean temperature and pH were 25.4 ± 1.14°C and 8.0 ± 1.5, respectively; and moisture content increased with pit sludge depth, except between Depths 3 and 4. Average moisture content was 86.3 ± 3%. The measured parameters varied significantly (P > 0.05) between seasons. The mean reduction in total coliforms, thermo-tolerant coliforms, E. coli, and faecal enterococci with sludge depth was significant at all depths (P < 0.05), but the least significant difference was not significant at depth levels of 1.0 m and 1.5 m. Salmonella was only detected at the top layer of faecal sludge in 60% of Phase 2 samples and in only 20% of the samples in Phase 3. About 200–4 100 eggs/g of strongyles were found in 98% of the samples and 100–1 600 eggs/g of ascarids in 55% of the samples. Temperature, pH and moisture content did not show a significant correlation with observed reductions of indicators and pathogens. With extrapolation of the generated regression models, a pit of 8 m can be recommended for reduction of bacteria. It is recommended that protective field gear be used during pit emptying and that faecal sludge treatment should be done to reduce pathogens before disposal into the environment.
Performance Evaluation and Optimization of the Maize Shelling Operation of the Multi-Purpose Farm Vehicle
(CIGR Journal, 2020) Nsubuga, Denis; Kabenge, Isa; Zziwa, Ahamada; Kiggundu, Nicholas; Wanyama, Joshua; Banadda, Noble
Small-scale farmers register high postharvest losses partly due to failure to carry out primary processing operations. Most of the maize shellers on the Ugandan market lead to high percentage of broken maize grains thus raising the risk of aflatoxin infection during storage. In this study, the operation of an existing maize sheller on the market with a shelling speed of 870 rpm for maize at 13 % moisture content was tested. The main objective of this study therefore was twofold; (i) to develop and evaluate a maize sheller and (ii) to optimize the multi-purpose vehicle shelling operation. The improved maize sheller was designed, fabricated, evaluated and optimized using a factorial experiment with shelling speed and moisture content as the main effects at three levels. Analysis of Variance was done using R-studio. A cost-benefit analysis of the shelling technology was conducted. The obtained results showed that a reduction in moisture content and an increase in shelling speed increased the shelling efficiency, the grain damage percentage, output capacity and the cleaning efficiency. The optimum moisture content and the shelling speed of the multi-purpose vehicle maize shelling were 13% and 896 rpm respectively. Except the shelling efficiency, the results of the modified maize sheller were significantly different (p<0.05) from those of the market sheller. The payback period was 1.37 years while the benefit-cost ratio was 1.07. The optimized maize shelling operation of the multi-purpose vehicle is therefore economically viable.
Quantification Of Physico-Chemical Characteristics And Modeling Faecal Sludge Nutrients From Kampala City Slum Pit Latrines
(Int. J. Res. Eng. Adv. Technol, 2016) Kimuli, Daniel; Zziwa, Ahamada; Banadda, Noble; Kabenge, Isa; Kiggundu, Nicholas; Kambugu, Robert; Wanyama, Joshua; Tumutegyereize, Peter; Kigozi, Julia
Failure to quantify nutrients in feacal sludge usually leads to its poor disposal resulting into surface water and groundwater pollution. Therefore, this study was conducted to determine and model the distribution of nutrients in pit latrine sludge as a step towards reuse of available nutrients. Sampling was done at 0.0, 0.5, 1.0 and 1.5 m depths from 31 lined and 31 unlined latrines during rainy and dry season. Physico-chemical characteristics such as chemical oxygen demand (COD), dissolved oxygen (DO), moisture content, temperature and nutrients including ammonia,nitrate, total nitrogen, phosphorus and potassium were determined. Results indicated that COD, temperature and DO decreased and moisture content increased with sludge depth. There was no significant variation (P˃0.05) in nutrients and physico-chemical properties except COD. Strong correlations of R2 Adj ˃ 0.85 were obtained between modeled and measured values. The relative root mean square error of the predicted nutrients was less than 10%. Results revealed that the model is good estimator phosphorus concentrations in lined pits followed by total nitrogen in unlined pits and nitrates in lined pits.
Relative efficiency of sawmill types operating in Uganda's softwood plantations
(Uganda Journal of Agricultural Sciences, 2005) Kambugu, Robert K.; Banana, Abwoli Y.; Zziwa, Ahamada; Agea, Jacob G.; Kaboggoza, John R. S.
The overall aim of this study was to determine the appropriate saw milling technologies that should be promoted for use in Uganda's softwood plantation. Conversion efficiency, sawing accuracy, and sawing capability of four sawmill categories were evaluated. Data were collected from sawing of 604 good Aquality logs using eleven Rolling ATable Sawmills, Dimensional Swivel Sawmills, Band Sawmills, and Locally Afabricated Snwmills. Sawing accuracy data were collected from 165 boards in three timber sizes (75 mm x 50 mm, 100 mm x 50 mm, 150 mm x SO mm). Sawing capability was assessed from saw blade parameters, merchantable timber size, and size of available logs. AN OVA was used to show differences in recovery and sawing accuracy between and within sawmills. Band sawmills exhibited the most efficient sawmill technology for converting logs into sawn timber while rolling-table sawmills were more efficient than dimensional swivel and locally manufactured sawmills. Band sawmills were more accurate than sawmills in the other categories. Therefore, band sawmills should be promoted in Uganda and mechanical modifications carried out on the swivel and locally-manufactured sawmills operating in softwood plantations to improve their feed A work and setwork mechanisms
Reverse Engineering of Plastic Waste into Useful Fuel Products
(Journal of Analytical and Applied Pyrolysis, 2018) Owusu, Prosper Achaw; Banadda, Noble; Zziwa, Ahamada; Seay, Jeffrey; Kiggundu, Nicholas
This paper’s twofold aims are: to assess the potential of converting plastic waste into useful fuels in both continuous and batch pyrolysis reactors using an appropriate technology and to investigate the effect of silica-alumina catalyst on the yield and quality of pyrolytic liquid oil. The plastic waste used (HDPE, PP and PS) were obtained from Kiteezi landfill site, Kampala (Uganda). In a further step, the properties of the liquid fuel obtained from pyrolysis were also compared with commercial transportation fuel to ascertain its suitability on diesel engines.The fuel qualities were analysed using ASTM standard test methods At a degradation temperature of 450 °C, thermal pyrolysis in a batch reactor resulted in the highest yield of liquid fractions. The liquid yield of HDPE, PP and PS was found to be 80%, 82.6% and 80% by mass, respectively. In contrast, silica-alumina catalyst to feedstock ratio of 1:10 was the most effective in terms of gaseous fraction production. The gaseous fractions were: 60 wt% for the mixture, followed by HDPE (59.63 wt%), PS (59.07 wt%) and PP (49.33 wt%). A catalyst/polymer ratio of 1:10 greatly reduced the degradation temperature. The degradation temperature for HDPE, PP and PS was reduced by about 33%, 23% and 17%, respectively. The liquid oils from HDPE and PP had densities of 0.796 g/cm3 and 0.786 g/cm3; kinematic viscosities of 2.373 mm2/s and 2.115 mm2/s, dynamic viscosities of 1.889 mPas and 1.856 mPas; boiling point ranges of 119–364 °C and 148–355 °C; and cetane indices of 46 and 63, respectively. The characteristics of HDPE and PP pyrolytic sample oils are similar to conventional transportation fuel.
Structural suitability of 10-year old Pinus caribaea timber with a forest fire history in farm buildings
(Agricultural Engineering International: CIGR Journal, 2020) Zziwa, Ahamada; Mukasa, Joseph; Kizito, Simon
Forest fires in pine and eucalyptus plantations are common in Uganda especially in the dry periods. In an event of fire gutting a nearly mature plantation, tree farmers usually try to reduce losses by extracting and lumbering the residual trees for use in agricultural buildings. However, there is no empirical data to guide material selection based on strength and structural integrity of the timbers from burnt plantations. Therefore, this study investigated the effect of fires on selected physical and strength properties of timber extracted from a 10-year old stand of Pinus caribaea that had been burnt. Test specimens were prepared and tested for Modulus of elasticity (MOE), Modulus of Rupture (MOR) and compression parallel to the grain using a Testometric AX M500 – 25KN Universal Testing Machine in accordance with ASTM D 198 and BS 373. For comparison purposes, structural size specimens from the same age stands that were unaffected by fire were concurrently tested. The data were statistically analyzed using one-way Analysis of Variance test. The results indicated that burnt trees had significantly lower density, MOE and MOR than that of the unburnt trees. It is recommended that timber extracted from burnt trees should not be used for high strength structural purposes but could rather be used in low strength construction works such as shuttering and ceiling works.
Transforming corn stover to useful transport fuel blends in resource-limited settings
(Energy Reports, 2021) Munu, Nicholas; Banadda, Noble; Kiggundu, Nicholas; Zziwa, Ahamada; Kabenge, Isa; Seay, Jeffrey; Kambugu, Robert; Wanyama, Joshua; Schmidt, Albrecht
Development of local technologies is crucial to the sustainable energy agenda in resource-limited countries and the world. Strengthening local green technologies and promoting local utilization will reduce carbon emissions that could be generated during transportation and delivery of green products from one country to another. In this paper we developed bio-oil/diesel blends using a low-tech pyrolysis system designed for smallholder farmers in developing countries and tested their appropriateness for diesel engines using standard ASTM methods. Corn stover retrieved from smallholder farmers in Gayaza, Uganda were pyrolyzed in a batch rocket stove reactor at 350 ◦C and liquid bio-oil harvested. Bio-oil chemical composition was analyzed by Gas Chromatography equipped with Flame Ionization Detector (GC-FID). Bio-oil/diesel emulsions in ternary concentrations 5%, 10% and 20% bio-oil weight were developed with 1% concentration of sorbitan monolaurate as an emulsifier. The bio-oil/diesel emulsions and distillates had property ranges: specific gravities at 15 ◦C 827.4–830.7 kg m−3, specific gravities at 20 ◦C 823.9–827.2 kg m−3, kinematic viscosities at 40 ◦C 3.01–3.22 mm2/s, initial boiling points 140–160 ◦C, final boiling points 354–368 ◦C, and calculated cetane indexes 56.80– 57.63. These properties of the bio-oil/diesel blends and their distillates compare well with standard transportation diesel fuel. The emulsion distillates meet the standard requirements for automotive diesel in East Africa.

Browsing by Author "Zziwa, Ahamada"

Results Per Page

Sort Options