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Advisor(s)
Abstract(s)
Portugal produz anualmente cerca de 100 mil t de azeite, 5% da produção mundial. Durante
o processo produtivo geram-se mais de 547 mil t/ano de bagaço de azeitona (BA). Atualmente,
o BA não tem valor económico, tendo os lagares que assumir o custo de transporte até as
extratoras de azeite lampante, pelo que urge procurar alternativas mais sustentáveis. O BA
contém elevado teor em C orgânico (lenhina), tornando-o ideal para a elaboração de compostos
de alta qualidade. No entanto é um material com elevado teor em água e fitotóxico quando não
devidamente gerido. Neste trabalho, apresentam-se resultados dum ensaio experimental de
compostagem a escala industrial (pilhas de 27m3
) durante 120 dias (d), usando como matériaprima principal o BA, além de estrume de ovelha (EO) e um “agente estruturante” (AE). O ensaio
permitiu testar o efeito da mistura das matérias-primas (assegurando C/N>30), doses de AE e
revolvimento mecânico. Foram realizadas amostragens para determinar humidade, densidade,
granulometria, cor, cinzas, pH, condutividade elétrica (CE), C total e N total, para além das
relações atómicas por análises elementar (H/C, O/C) e a espectroscopia de infravermelhos (IR).
Os resultados preliminares mostram que a fase termófila foi atingida nos primeiros 10 d,
mantendo-se 8 semanas até a fase de maturação. Perdas de peso de até 30% nos primeiros 30
d, e razões C/N na ordem de 25 em 60 d. Aos 120 d, o composto tinha uma cor escura, ausência
de odor desagradável, C/N<20 e baixa fitotoxicidade. Os espetros IR mostraram que os ácidos
gordos, os polifenóis e as lenhinas são transformadas na fase inicial da compostagem. Ao reduzir
o tempo da compostagem (de 9 para 5 meses), é possível reduzir os custos da compostagem
convencional de BA e contribuir para a sustentabilidade da agricultura regional.
Portugal produces about 100,000 t/y of olive oil, 5% of world production. During the production process, more than 547,000 t/y of olive pomace (OP) are generated. Currently, OP has no economic value, the transportation costs to deliver it in secondary extraction factories being covered by the olive mills; as so, it is urgent to look for more sustainable alternatives for this material. OP contains high organic C content (lignin), making it ideal for the preparation of high-quality compost. However, it is a pasty material with high water content and phytotoxic when not properly managed. In this work, the results of an experimental industrial scale composting test (27m3 heaps) for 180 days are presented, using OP as the main raw material, in addition to other raw materials and a "structuring agent" (SA). The essay allowed testing the effect of mixing the raw materials (ensuring C/N>40), doses of SA and manual aeration. Seven samples were taken to determine moisture, density, particle size, ash content, pH, EC, total C and total N, in addition to the atomic relationships by elemental analysis and FTIR infrared spectroscopy. Preliminary results show that the thermophilic phase was reached in the first 10 days, remaining for 8 weeks until the maturation phase. Weight loss of up to 30% in the first 30 days, and C/N ratios in the order of 25 in 60 days. At 120 days, the compost had a dark color, “good smell”, C/N<20 and low phytotoxicity. IR spectra showed that fatty acids, polyphenols and lignin are transformed in the initial phase of composting. By reducing the composting time (from 9 to 5 months), it is possible to reduce the costs of conventional composting and contribute to the sustainability of regional agriculture.
Portugal produces about 100,000 t/y of olive oil, 5% of world production. During the production process, more than 547,000 t/y of olive pomace (OP) are generated. Currently, OP has no economic value, the transportation costs to deliver it in secondary extraction factories being covered by the olive mills; as so, it is urgent to look for more sustainable alternatives for this material. OP contains high organic C content (lignin), making it ideal for the preparation of high-quality compost. However, it is a pasty material with high water content and phytotoxic when not properly managed. In this work, the results of an experimental industrial scale composting test (27m3 heaps) for 180 days are presented, using OP as the main raw material, in addition to other raw materials and a "structuring agent" (SA). The essay allowed testing the effect of mixing the raw materials (ensuring C/N>40), doses of SA and manual aeration. Seven samples were taken to determine moisture, density, particle size, ash content, pH, EC, total C and total N, in addition to the atomic relationships by elemental analysis and FTIR infrared spectroscopy. Preliminary results show that the thermophilic phase was reached in the first 10 days, remaining for 8 weeks until the maturation phase. Weight loss of up to 30% in the first 30 days, and C/N ratios in the order of 25 in 60 days. At 120 days, the compost had a dark color, “good smell”, C/N<20 and low phytotoxicity. IR spectra showed that fatty acids, polyphenols and lignin are transformed in the initial phase of composting. By reducing the composting time (from 9 to 5 months), it is possible to reduce the costs of conventional composting and contribute to the sustainability of regional agriculture.
Description
Keywords
Fitotoxicidade Lehnina Espectroscopia FTIR Sustentabilidade Economia circular
Citation
Hernández Hernández, Zulimar; Figueiredo, Daniel; Royer, Ana Caroline; Madeira, Filipe; Figueiredo, Tomás de (2022). Otimização do processo industrial de compostagem de bagaço de azeitona no nordeste de Portugal. In IX Simpósio Nacional de Olivicultura. Oeiras. p.53-61. ISBN 978-972-8936-46-4
Publisher
Associação Portuguesa de Horticultura (APH)