Abstract Marigold (Calendula officinalis) market is focused on the extraction of compounds from the flower for homeopathic applications. However, most of the body plant is left as waste for final disposition. This work aims to show an integral valorization of leaves and stem of marigold to produce biogas and phenolic compounds such as vanillin and vanillic acid in a biorefinery scheme. An alkaline pretreatment was carried out to obtain black liquor and to favor the digestibility of the solid residue. The black liquor was oxidized in a high-pressure reactor, reaching experimental yields of 5.09% and 1.16% (based on lignin) for vanillin and vanillic acid, respectively. The remaining solid fraction was fermented through anaerobic digestion, achieving biogas productivity of 1621.3 mL/g of volatile solids. Afterward, these experimental results were used as input parameters to simulate and analyze a potential biorefinery. It was demonstrated that the anaerobic digestion stage affects up to 59% of the capital costs and that the positive economic gains were achieved at flow rates greater than 6.64 ton/h.

中文翻译：

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用于对万寿菊（Calendula officinalis）残留物进行增值以生产沼气和酚类化合物的生物精炼厂

摘要万寿菊 (Calendula officinalis) 市场专注于从花中提取化合物以用于顺势疗法应用。然而，大部分身体植物都作为废物留待最终处置。这项工作旨在展示万寿菊叶和茎的整体增值，以在生物精炼方案中生产沼气和酚类化合物，如香草醛和香草酸。进行碱性预处理以获得黑液并有利于固体残渣的消化。黑液在高压反应器中氧化，香草醛和香草酸的实验产率分别达到 5.09% 和 1.16%（基于木质素）。剩余的固体部分通过厌氧消化进行发酵，达到 1621.3 mL/g 挥发性固体的沼气生产率。之后，这些实验结果被用作输入参数来模拟和分析潜在的生物精炼厂。结果表明，厌氧消化阶段影响了高达 59% 的资本成本，并且在流速大于 6.64 吨/小时时实现了积极的经济收益。