Assessing soil erosion risk in a peri-urban catchment of the Lake Victoria basin.

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.

Biofuel characteristics of non-charred briquettes from dried fecal sludge blended with food market waste: Suggesting a waste-to-biofuel enterprise as a win-win strategy to solve energy and sanitation problems in slums settlements.

This study explored the production and evaluation of briquettes made from dried fecal sludge mixed with fresh food waste as a dual strategy to solve energy poverty and poor sanitation problems in Ugandan slums. Cylindrical briquettes measuring 82 mm height by 76 mm diameter were produced from dried fecal sludge (FS) alone, and FS mixed separately with pineapple peels (FS + PP), charcoal fines (FS + CD), and bean husks (FS + BH) in a mix ratio of 50% FS: 50% biomass (wt/wt basis) using red soil as the binder. Physiochemical characteristics and fuel thermal efficiency of the briquettes were tested following ASTM standards and were compared to wood-derived charcoal and commonly traded briquettes on market in Uganda. The average moisture content was 5.1%. Bulk density was highest in FS briquettes (1.12 g/cm3) and lowest in FS + BH (0.847 g/cm3). Volatile matter (VM) was highest in FS + PP (39%) and lowest in FS alone (25.7%). The average ash content was 30.4%. FS + PP had the highest calorific value (17.92 MJ/kg) while FS alone had the lowest (6.19 MJ/kg). The highest burning rate was recorded in FS + CD briquettes (8 g/min) and was lowest in FS + PP (4 g/min). Based on the calculated burning rates and calorific values, the economic advantage calculations implied that blending one ton of dry FS with one ton of dry pineapple peels for fuel briquettes, and their use as a substitute could save consumers about USD 620 per ton of wood charcoal foregone.

Nutrient recovery from pineapple waste through controlled batch and continuous vermicomposting systems.

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.