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<p>Banana waste is a promising substrate for anaerobic digestion due to its high organic content; however, the recalcitrance of lignocellulosic structures limits hydrolysis efficiency. This study evaluated the effect of alkaline thermal pretreatment of banana waste using sodium hydroxide (NaOH) at concentrations ranging from 0.2% to 3.0%, aiming to enhance carbohydrate solubilization and methane production. Anaerobic batch reactors (1&#xa0;L) fed with pretreated banana waste in alkaline hydrolysis with NaOH as the main substrate were operated at 37&#xa0;°C for 15 days under mesophilic conditions, with co-digestion using synthetic sewage. Seven assays were evaluated: assay 1 (0.2% NaOH), assay 2 (0.4% NaOH), assay 3 (0.5% NaOH), assay 4 (1.0% NaOH), assay 5 (2.0% NaOH), assay 6 (3.0% NaOH) and assay 7 (control). The highest carbohydrate release was obtained by assay 1 (0.2% NaOH) with 12,110 mgL<sup>− 1</sup>, whereas untreated waste exhibited the lowest solubilization (4785 mgL<sup>− 1</sup>). The highest cumulative methane production was observed in assay 2 (0.4% NaOH), reaching 2471 mLCH₄Lr<sup>− 1</sup>, while the maximum methane production rate was achieved in assay 1 (0.2% NaOH), with 525.21 mL CH₄ Lr⁻¹ d⁻¹. Carbohydrate removal exceeded 98% in all assays, whereas COD removal ranged from 71.58% to 94.54%. Metagenomic analysis of assay 2 revealed the predominance of <i>Paraclostridium</i> and <i>Clostridium</i> among bacteria and <i>Methanothrix</i> and <i>Methanoregula</i> among archaea, indicating a shift from acetoclastic to hydrogenotrophic methanogenesis. Overall, the management of lignocellulosic biomass, aligned with circular economy principles, promotes the valorization of lignocellulosic agricultural waste into value-added products such as biogas, enhancing resource recovery and sustainability.</p> Graphical Abstract <p>Graphical abstract illustrating the effect of alkaline hydrolysis pretreatment on banana waste anaerobic digestion, highlighting the trade-off between methane production rate and cumulative yield and the associated microbial pathway shifts.</p> <p></p>

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Agroindustrial Banana Wastes Applied in Biogas Production: Evaluation of Thermal Pretreatment on Alkaline Hydrolysis

  • 期刊论文

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  • 发表日期：

    2026年5月25日

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  • Larissa Ayumi Yamamoto,
  • Ana Gabriela Oliveira Ferreira Janas,
  • Sandra Imaculada Maintinguer

摘要

Banana waste is a promising substrate for anaerobic digestion due to its high organic content; however, the recalcitrance of lignocellulosic structures limits hydrolysis efficiency. This study evaluated the effect of alkaline thermal pretreatment of banana waste using sodium hydroxide (NaOH) at concentrations ranging from 0.2% to 3.0%, aiming to enhance carbohydrate solubilization and methane production. Anaerobic batch reactors (1 L) fed with pretreated banana waste in alkaline hydrolysis with NaOH as the main substrate were operated at 37 °C for 15 days under mesophilic conditions, with co-digestion using synthetic sewage. Seven assays were evaluated: assay 1 (0.2% NaOH), assay 2 (0.4% NaOH), assay 3 (0.5% NaOH), assay 4 (1.0% NaOH), assay 5 (2.0% NaOH), assay 6 (3.0% NaOH) and assay 7 (control). The highest carbohydrate release was obtained by assay 1 (0.2% NaOH) with 12,110 mgL− 1, whereas untreated waste exhibited the lowest solubilization (4785 mgL− 1). The highest cumulative methane production was observed in assay 2 (0.4% NaOH), reaching 2471 mLCH₄Lr− 1, while the maximum methane production rate was achieved in assay 1 (0.2% NaOH), with 525.21 mL CH₄ Lr⁻¹ d⁻¹. Carbohydrate removal exceeded 98% in all assays, whereas COD removal ranged from 71.58% to 94.54%. Metagenomic analysis of assay 2 revealed the predominance of Paraclostridium and Clostridium among bacteria and Methanothrix and Methanoregula among archaea, indicating a shift from acetoclastic to hydrogenotrophic methanogenesis. Overall, the management of lignocellulosic biomass, aligned with circular economy principles, promotes the valorization of lignocellulosic agricultural waste into value-added products such as biogas, enhancing resource recovery and sustainability.

Graphical Abstract

Graphical abstract illustrating the effect of alkaline hydrolysis pretreatment on banana waste anaerobic digestion, highlighting the trade-off between methane production rate and cumulative yield and the associated microbial pathway shifts.