Research Article
Volume 5 Issue 5
Onwujiariri CE*, Bull OS, Boisa N and Gogonte EE
April 28, 2025
Abstract
As a result of high cost of fossil fuel and upsurge use of wood as an alternative source of fuel for domestic cooking and growing concern about the health risk associated with this practice, warranted the combustion and harvest of fly ash from selected fire woods such as African Oil Bean (Ugba), African Velvet Tamarind (Icheku), African Mango (Ugiri), African Pear (Ube), Mango (Mangoro) and African Bread Fruit (Ukwa) commonly used in Oru Community, Ahiazu-Mbaise, Imo State, South East Nigeria. Characterization of their fly ashes was carried out in order to determine the woods that generate lesser pollutants into the atmosphere. The woods fly ash were generated and analyzed for Heavy metals, Polycyclic Aromatic Hydrocarbons (PAHs), Morphology and Mineral contents. Heavy metals (Nickel, Zinc, Chromium, Manganese, Cadmium and Lead) were analyzed using Atomic Absorption Spectrophotometer (AAS), 16-priority PAHs were analyzed using Gas Chromatography-Mass Spectrometer (GC- MS), Minerals were determined using X-ray Diffractometer (XRD) and Scanning Electron Microscope (SEM) was used to determine the morphology of the fly ashes. The results obtained showed low concentrations of heavy metals in the fly ash of the woods, which were below W.H.O permissible limit (2.0mg/kg) except lead (Pb) and zinc (Zinc) that recorded high concentrations in all the fly ashes. PAHs concentrations across the fly ashes recorded an average value range from (0.02 mg/kg - 0.21 mg/kg) which was below USEPA permissible exposure limits (0.02 mg/kg - 0.5 mg/kg). Total PAHs concentrations recorded in woods fly ash were between (0.02 mg/kg and 4.63 mg/kg). Icheku wood fly ash recorded the highest total concentration of PAHs (4.63 mg/kg) while Ube wood fly ash, had the least (0.2 mg/kg). Highly carcinogenic PAHs such as Benzo (b) Fluoranthenene, Benzo (a) Pyrene, Benzo (k) Fluranthene, Chrysene, Dibenzo (G,h) anthracene and Indeno (1,2,3 c-d)were not detected in the woods fly ash. For minerals, mangoro fly ash recorded the most abundant essential mineral (24.97%) phosphorus content while Ugba fly ash recorded the lowest essential mineral (16.21%) sodium content. Aluminum and lithium, which are non- essential mineral elements, were found in the woods fly ash. SEM analysis in the woods fly ash recorded results of the range of particle sizes. Ugba (16 µm - 66 µm), Icheku (16 µm -200 µm) Ugiri (10 µm - 33 µm) Ube (36 µm -76 µm) Mangoro (20 µm - 60 µm) and Ukwa (33 µm - 86 µm). Icheku fly ash recorded the largest particle size range(16 µm - 200 µm) which is above the USEPA threshold value range (10 µm - 100 µm) for woods fly ash inhalation while Ugiri fly ash recorded the lowest particle size range (10 µm - 33 µm). From the SEM results, constant exposure to the woods fly ash could possibly lead to lungs inflammation and other respiratory diseases especially that of Ugiri wood. The best woods in relation to Heavy metals concentrations, PAHs, Particle sizes and Minerals are Ugba and Mangoro wood and are recommended for wood fuel. Other woods like Ube, Ukwa and Ugiri are also recommended for usage but under strict regulation, while Icheku wood should be rarely used since it contains very high concentrations in all the parameters analyzed in this study.
Keywords: Fly Ash; Biomass (wood); Oru; Ahiazu-Mbaise (Imo State)
References