Potential of Densification of Mango Waste and Effect of Binders on Produced Briquettes

In Uganda, agro-processing of fruits produces large volumes of agricultural wastes much of which are not utilized but disposed in the landfill. This study explored the possibility of producing biomass briquettes from mango waste (seed covers) that could be used for energy supply in small factories and for domestic cooking. Dried mango seed covers were crushed to particles of size 2 mm and bonded with three different binders; starch, starch-clay soil, and starch-red soil. The best mixing ratios for briquettes were; 4:1 (seed-cover: starch), 9:2:1 (seed cover: starch: clay soil), and 16:4:1 (seed-cover: starch: red soil). The formed briquettes were subjected to several standard methods to verify their suitability as fuels. The briquette properties tested were moisture content, volatile matter, ash content, fixed carbon content, calorific value, compressive strength, and gaseous emissions. Results showed that briquettes bonded with only starch had a significantly (p ≤ 0.05) higher fuel properties with low: moisture content (11.9%), volatile matter (16.0%), ash content (2.8%) and emissions (0.178% CO, 0.0021% (CH)X , 1.14% CO2 and no NOx); higher fixed carbon (69.3%), breaking strength (maximum force, 34 N and compressive stress, 273 N/mm2) and calorific values (16,140 KJ/Kg)  compared to starch-red soil and starch-clay soil briquettes.  But after a linear regression analysis, results further showed that maximum force (R2 = 0.636) and ash content (R2 = 0.520) were good indicators of energy content of a particular briquette. However, more research is needed on using other binder types rather than cassava starch which is considered as food

Modeling sludge accumulation rates in lined pit latrines in slum areas of Kampala City, Uganda

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.Keywords: Faecal, sludge accumulation rates, slum areas, lined pit latrine

Contextual investigation of factors affecting sludge accumulation rates in lined pit latrines within Kampala slum areas, Uganda

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.Keywords: sludge accumulation rates, slum areas, faecal matter, degradation, lined pit latrine

Factors affecting dairy production in peri-urban areas of Kampala

The number of small holder dairy farms in the peri-urban areas of Kampala are increasing. This could be due to the high demand for dairy products by the increasing urban population and the need to provide an alternative source of income especially for the resource poor urban population. The farmers rear both improved breeds and local breeds. However, no detailed study has been carried out to address the factors that affect peri-urban dairy production. A survey was carried out in the peri-urban areas of Kampala to find out how these factors affect production. Specifically the study aimed at investigating how socio-economic factors affect dairy production. The econometric model (Cobb-Douglas production function) and descriptive statistics were used. The results showed that the breed of the cows, experience in dairy farming, purchased feeds and labour were the biggest vAriables affecting dairy farming in the peri-urban areas of Kampala city.lt was therefore recommended that if milk production in the peri-urban areas of Kampala is to be increased, farmers should be encouraged to rear improved breeds.Key words: Dairy production, peri-urban, Kampal