Browsing by Author "Kambugu, Robert"
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Item 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, RobertDeclining 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.Item 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, PeterPit 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.Item 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.Item 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, PeterDisposal 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.Item 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 TumutegyereizeDisposal 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.Item 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 JohnOccurrence 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.Item 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, JuliaFailure 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.Item 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, AlbrechtDevelopment 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.