ABSTRACT

Anaerobic mono- and co-digestion of fruits and vegetable waste (FVW), slaughterhouse waste (SHW), and cattle manure (CM) under mesophilic conditions (35°C) were conducted through biochemical methane potential tests to investigate how the FVW in a co-substrate formulation improves the methane yield, the degradative synergy between substrates, and especially the stability of the process. The co-digestion of FVW:SHW and FVW:CM were evaluated with volatile solids (VS) ratios of 1:2, 1:1, and 2:1. The results indicated that the highest synergistic effect was found in the co-digestion FVW:CM at 1:1 VS ratio. However, the co-digestion FWV:SHW at 1:2 VS ratio increased the methane yield by 74.2% compared to the mono-digestion of FVW (776.3 mL CH₄ g VS_added⁻¹). As a critical condition in these processes, the stability was evaluated using the early warning indicator VFA/TA (volatile fatty acids/total alkalinity). The co-substrate SHW promotes greater stability in methane production as the soluble carbohydrate content in FVW increases. It was proposed that the high protein (49.04 ± 0.96% VS) and ammonia content (693 ± 3 mg L⁻¹) of SHW leads to the formation of a dampening system known as a carbonate-acetic buffer. It was concluded that balanced distribution between carbohydrates, proteins, and lipids is crucial to increase methane yields, and the low methane productions were associated with low N-NH₄⁺ concentrations (FVW:CM co-digestions). The results obtained in this study can serve as a basis to design full-scale digesters under similar operating conditions and with the same substrate:co-substrate relationships.

Implications: The production of methane from the anaerobic digestion process of food, and lose waste presents a viable alternative of valorization and could help to mitigate environmental impacts. However, anaerobic digestion from these substrates carries high instabilities and low methane yields. The need to increase these yields and contribute to process stability must be considered in the selection of a co-substrate. In this context, this work aims to evaluate the best fruits and vegetable waste: co-substrateformulation, that promotes higher methane yield, a synergy between substrates, and to improve the AD process stability in the presence of perturbations in the substrate composition. We believe that our results could be helpful for the design processes for methane production from fruit and vegetable waste, to contribute to competitiveness with conventional energies and promote the sustainability of these processes.

摘要

在中温条件（35°C）下对水果和蔬菜废物 (FVW)、屠宰场废物 (SHW) 和牛粪 (CM) 进行厌氧单消化和联合消化，通过生化甲烷潜力测试来研究 FVW 在共底物配方提高了甲烷产率、底物之间的降解协同作用，尤其是过程的稳定性。FVW:SHW 和 FVW:CM 的共消化用挥发性固体 (VS) 比为 1:2、1:1 和 2:1 进行评估。结果表明，在 1:1 VS 比率的共消化 FVW:CM 中发现了最高的协同效应。然而，与 FVW 的单消化（776.3 mL CH ₄ g VS_添加^-1）。作为这些过程中的一个关键条件，稳定性使用预警指标 VFA/TA（挥发性脂肪酸/总碱度）进行评估。随着 FVW 中可溶性碳水化合物含量的增加，共底物 SHW 促进了甲烷生产的更大稳定性。有人提出，SHW 的高蛋白质 (49.04 ± 0.96% VS) 和氨含量 (693 ± 3 mg L ^-1 ) 导致形成称为碳酸盐-乙酸缓冲液的润湿系统。得出的结论是，碳水化合物、蛋白质和脂质之间的平衡分布对于提高甲烷产量至关重要，而低甲烷产量与低 N-NH ₄ ^{+ 相关}浓度（FVW：CM 共消化）。本研究中获得的结果可作为在类似操作条件下和相同底物：共底物关系下设计全尺寸消化器的基础。

影响：从食物的厌氧消化过程中产生的甲烷和浪费的废物是一种可行的价值化替代方法，有助于减轻对环境的影响。然而，这些底物的厌氧消化具有高不稳定性和低甲烷产率。在选择共基材时，必须考虑增加这些产量和有助于工艺稳定性的需要。在这种情况下，这项工作旨在评估最好的水果和蔬菜废物：共底物配方，促进更高的甲烷产量，底物之间的协同作用，并在底物成分存在扰动的情况下提高 AD 过程的稳定性。我们相信我们的结果可能有助于从水果和蔬菜废物中生产甲烷的设计过程，