Potassium Recovery Potential of Selected Agroforestry and Organic Wastes in Ibadan, Nigeria

This study explored potassium recovery from agroforestry wastes that may be a cheap alternative to imported ones. The wastes: Plantain Peel (PP), Coconut Fibre (CF), Coconut Shell (CS), Cocoa Pod (CP), Sugarcane Bagasse (SB), Sawdust (SD) and four common wood-fuel species - Antiaris toxicaria (Wd1), Cordia millenii (Wd2), Khayas senegalensis (Wd3) and Milicia excelsa (Wd4) were assessed for their ash content (AC) and moisture content (MC), using standard procedures of AOAC. Atomic Absorption spectrophotometer was used to determine mineral concentrations: potassium, sodium, magnesium, calcium, zinc, lead and iron of the wastes. In addition, efficacy of three methods of extracting potassium from ashes: cold water extraction at 35 OC, hot water extraction at 90 OC and steam extraction was assessed. Data were analysed using descriptive statistics and correlation test at p˂0.05. Wastes with highest values in terms of AC and MC were: CP (AC- 11.62 ± 0.3 %) and SB (MC- 82 ± 2.64 %). The highest concentration of K (mg·kg -1 ) was found in CP (8,387.50 ± 2.00 mg·kg-1 ). Cold water extraction gave the most potassium yield (88.44 %) and the highest solid potash content was found in PP (68 500 mg·kg -1 ) while CP had the highest K concentration (12.51±0.20 g·dm-3 ). Cocoa pod, plantain peel and Cordia millenii are very good sources of agroforestry/organic wastes for local production of potassium both in terms of solid potash yield and potassium recovery potential. Development of a suitable technology which can be used to extract potassium locally is recommended

Low Emission, Smoke Free Charcoal from Oil Palm (Elaeis Guineensis) Waste- A Cheap Energy Source for Rural Communities in Nigeria

The use of oil palm (Elaeis guineensis) waste as a potential source of soil conditioner in agriculture has long been identified. Its conversion into smokeless and low emission charcoal which is more environmental friendly has not been well investigated. The present study explored conversion of oil palm waste into low emission charcoal. Palm Kernel Fibre (PKF) and Palm Kernel Shell (PKS) were subjected to a pyrolytic process in a Closed Drum Carboniser (CDC). The raw waste and the gaseous emissions that emanated during processing of wastes and during use for cooking were analysed for its mineral composition and emissions of CO, CO2, SO2, NO2 and PM2.5 contents respectively using potable digital gas monitoring equipment and gravimetric PM sampler. The PKS had low nitrogen: (0.02 ± 0.03) Ma.-% and phosphorus: (0.18 ± 0.10) Ma.-% required for plant growth but high in potassium: (3.24 ± 2.49) Ma.-% which can be recovered from charcoal ash. The time taken to convert 25 kg of PKF and PKS into charcoal and their percentage volume reduction were: 1h: 13 min (90.00 Ma.-%) and 1h: 19 min (70 .00 Ma.-%) respectively. The charcoal produced from PKS exhibited higher stove value for cooking 200 g of rice within 25 min using 0.35 kg of the charcoal as against 28 min and 0.40 kg observed for conventional wood charcoal. The study showed that PKF and PKS form viable feed-stock to produce charcoal which emits less smoke and reduce greenhouse gas emissions when used as cooking fuels in households. Keywords: Closed drum carboniser, Low emission charcoal, Elaeis guineensis, Oil palm waste, Pyrolytic process, Stove energy valu