Avaliação da produção de biogás em reatores anaeróbios alimentados com resíduos alimentares e glicerol bruto
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Data
2022-08-04
Autores
Braga, Arthur Ivers
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Universidade Estadual Paulista (Unesp)
Resumo
O crescente olhar global dirigido para fatores ambientais levanta questões, envolvendo a
poluição descontrolada e a busca por energias renováveis, devido aos impactos naturais
provocados. Com isso, os combustíveis renováveis ganharam visibilidade e demanda. Um
exemplo é o biodiesel, produzido em larga escala, pela transesterificação, que, sendo
geradas elevadas concentrações de glicerol, tornando-se este último um problema
ambiental e econômico devido ao seu excedente, mesmo que ainda usado em alguns
setores industriais. Junto a isso, outra questão ambiental são os resíduos sólidos, como
orgânicos alimentares, mal reaproveitados, gerados diariamente, que podem poluir
mananciais e trazer vetores de doenças. Sendo assim, uma boa e viável alternativa para
enfrentar estes problemas é a digestão anaeróbia, com microrganismos adaptados, na
ausência de oxigênio, que degradam a matéria orgânica, produzindo compostos de
interesse, como metano (biogás) e outros elementos. Foram feitos ensaios de co-digestão
anaeróbia utilizando glicerol bruto e resíduos alimentares, para avaliar a produção de
biogás. O glicerol bruto foi oriundo de uma usina piloto de produção de biodiesel, e os
resíduos alimentares foram coletados em restaurantes próximos à Universidade.
Posteriormente, procedeu-se com os ensaios em reatores anaeróbios operados em
batelada utilizando três proporções de glicerol bruto: 0 %, 3 % e 6 % em volume. Análises
da fase líquida dos reatores foram efetuadas no início e ao final dos ensaios, para
avaliação da remoção de carboidratos, matéria orgânica e glicerol, além do
monitoramento periódico da produção de biogás. No ensaio com ausência de glicerol foi
obtida a melhor remoção de matéria orgânica, 81,12 %, e carboidratos (93,30 %). O
ensaio com 3 % de glicerol foi o melhor quanto ao volume de biogás produzido, atingindo
valores de 336,60 mL, além de possuir a segunda melhor remoção de matéria orgânica,
juntamente com a maior remoção do glicerol, com 99,68 %. Já o ensaio de 6 % de glicerol
obteve o menor e pior desempenho com máximo de 15,40 ml de biogás produzido, e a
segunda maior remoção de glicerol. Em vista dos resultados observados, constatou-se que
quando se adicionou 3 % de glicerol em co-digestão com resíduo alimentar, houve
aumento na produção de biogás (quando comparado ao ensaio com 0 % de glicerol) e
praticamente todo o glicerol foi removido. Entretanto, um aumento para 6 % de glicerol
co-digerido com resíduo alimentar não demonstrou bons resultados tanto de produção de
biogás quanto de remoção de glicerol ou DQO.
The growing global gaze directed at environmental factors raises questions, involving uncontrolled pollution and the search for renewable energies, due to the natural impacts caused. As a result, renewable fuels gained visibility and demand. An example is biodiesel, produced on a large scale by transesterification, which generates high concentrations of glycerol, making the latter an environmental and economic problem due to its surplus, even though it is still used in some industrial sectors. Along with this, another environmental issue is solid waste, such as food organics, poorly reused, generated daily, which can pollute water sources and bring disease vectors. Therefore, a good and viable alternative to face these problems is anaerobic digestion, with adapted microorganisms, in the absence of oxygen, which degrade organic matter, producing compounds of interest, such as methane (biogas) and other elements. Anaerobic co digestion assays were performed using crude glycerol and food residues to evaluate biogas production. The crude glycerol came from a pilot plant for the production of biodiesel, and the food waste was collected in restaurants close to the University. Subsequently, tests were carried out in anaerobic batch reactors using three proportions of crude glycerol: 0%, 3% and 6% by volume. Analyzes of the liquid phase of the reactors were carried out at the beginning and at the end of the tests, to evaluate the removal of carbohydrates, organic matter and glycerol, in addition to the periodic monitoring of biogas production. In the test without glycerol, the best removal of organic matter was obtained, 81.12%, and carbohydrates (93.30%). The test with 3% glycerol was the best in terms of the volume of biogas produced, reaching values of 336.60 mL, in addition to having the second best removal of organic matter, together with the highest removal of glycerol, with 99.68%. The 6% glycerol assay had the lowest and worst performance with a maximum of 15.40 ml of biogas produced, and the second highest glycerol removal. In view of the observed results, it was found that when 3% glycerol was added in co digestion with food waste, there was an increase in biogas production (when compared to the test with 0% glycerol) and practically all the glycerol was removed. However, an increase to 6% of glycerol co-digested with food residue did not show good results either in biogas production or in glycerol or COD removal.
The growing global gaze directed at environmental factors raises questions, involving uncontrolled pollution and the search for renewable energies, due to the natural impacts caused. As a result, renewable fuels gained visibility and demand. An example is biodiesel, produced on a large scale by transesterification, which generates high concentrations of glycerol, making the latter an environmental and economic problem due to its surplus, even though it is still used in some industrial sectors. Along with this, another environmental issue is solid waste, such as food organics, poorly reused, generated daily, which can pollute water sources and bring disease vectors. Therefore, a good and viable alternative to face these problems is anaerobic digestion, with adapted microorganisms, in the absence of oxygen, which degrade organic matter, producing compounds of interest, such as methane (biogas) and other elements. Anaerobic co digestion assays were performed using crude glycerol and food residues to evaluate biogas production. The crude glycerol came from a pilot plant for the production of biodiesel, and the food waste was collected in restaurants close to the University. Subsequently, tests were carried out in anaerobic batch reactors using three proportions of crude glycerol: 0%, 3% and 6% by volume. Analyzes of the liquid phase of the reactors were carried out at the beginning and at the end of the tests, to evaluate the removal of carbohydrates, organic matter and glycerol, in addition to the periodic monitoring of biogas production. In the test without glycerol, the best removal of organic matter was obtained, 81.12%, and carbohydrates (93.30%). The test with 3% glycerol was the best in terms of the volume of biogas produced, reaching values of 336.60 mL, in addition to having the second best removal of organic matter, together with the highest removal of glycerol, with 99.68%. The 6% glycerol assay had the lowest and worst performance with a maximum of 15.40 ml of biogas produced, and the second highest glycerol removal. In view of the observed results, it was found that when 3% glycerol was added in co digestion with food waste, there was an increase in biogas production (when compared to the test with 0% glycerol) and practically all the glycerol was removed. However, an increase to 6% of glycerol co-digested with food residue did not show good results either in biogas production or in glycerol or COD removal.
Descrição
Palavras-chave
Co-digestão, Digestão anaeróbia, Metano, Reator batelada, Anaerobic digestion, Batch reactor, Co-digestion, Methane