Abstract:
Elephant grass (EG) and palm empty fruit bunch fibre (EFB) have great potential for bioenergy. However, their high content of alkaline ash, chlorine and other contaminants hinders direct combustion by promoting slagging, fouling and pollutant emissions. To address this issue, the main goal of this study was to assess the effectiveness of water leaching as a mild and scalable pre-treatment to reduce the inorganic content of ash in EG and EFB, enhancing their suitability for thermochemical conversion. A factorial experimental design was applied to evaluate the effects of particle size, water-to-biomass ratio and leaching time on ash removal, using EG as a model biomass. Particle size was the most influential factor, enabling up to 41% ash reduction in milled biomass (<10 mm). Scale-up experiments under optimized conditions (14 L kg⁻¹, 10 min, <10 mm) validated the consistency of the selected parameters for both EG and EFB, with removal rates of 73.5-80% for Cl, 62.3-70.7% for K, and 50-60% for P. EG also showed a 57.1% reduction in N, contributing to NOₓ mitigation. Dry basis energy efficiency remained above 93.5%, while mass losses were below 9%. Although residual moisture (~70%) may limit direct combustion, mechanical dewatering is suggested. The leachate exhibited high conductivity and dissolved organic carbon, especially for EFB, suggesting potential for anaerobic digestion. Overall, pre-milling followed by water leaching proved to be an efficient strategy to reduce corrosive and ash-forming elements in EG and EFB, contributing to an improved inorganic profile of the biomass.
Referência:
ALMEIDA, Vittor R. S.; MOREIRA, Renata; MEYER, Dênis C.; SILVA, Ana P. de S.; BEZERRA, Breno V. R.; USHIMA, Ademar H. Enhancing combustion properties of elephant grass and palm empty fruit bunch fiber trhrough water leaching. In: BIOMASS AND BIOENERGY CONFERENCE, 2025, Sorocaba. Lecture and Pôster… 14 slides.
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