The overall objectives of this study were to evaluate the effectiveness of utilizing manure vermicompost as an additive to enhance anaerobic digestion of post-consumer cafeteria food waste in a single-stage digestion system and investigate the mechanisms associated with such enhancement. Vermicompost was chosen because of its buffering capacity, abundance of humic substance, and variety of trace metals, all of which may enhance the digestion process. The experiment was first conducted using a batch-scale biochemical methane potential assay and found that manure vermicompost added to the food waste reactors at concentrations of 2 g/L and 6 g/L both significantly increased ultimate methane yield and methane production rate. Then, a long-term study was conducted using twelve semi-continuous single-stage reactors to confirm such enhancement and further investigate the associated mechanism. The specific methanogenic activity and trace metal (iron, nickel, and cobalt) bioavailability were also evaluated. Results showed that the food waste digester without any supplement (control) had unstable and low methane production (254 mL/g VS added/day and 455 mL/g VS destroyed/day). During the experimental period, the control reactor experienced a dramatic reduction in pH (less than 6) due to a significant accumulation of volatile fatty acids (more than 2,600 mg/L). The trace metal bioavailability tests further demonstrated that the control digester could be deficient in nickel and iron. In contrast, the food waste digesters supplemented with manure vermicompost (2 g/L), trace metals (a mixture of 0.01 mg/L nickel, 0.5 mg/L Fe, and 0.01 mg/L Co) or humic acids (0.4 g/L) all had stable and significantly greater methane production compared to the control. The pH was approximately 7 and volatile fatty acids were less than 200 mg/L. Among all treatments, the food waste digesters supplemented with manure vermicompost had the greatest methane production (625 mL/g VS destroyed/day). In comparison to the control, supplementation of manure vermicompost also nearly doubled the acetate utilization rate and enhanced the propionate utilization rate by 60%. It was found that such enhanced digestion performance was likely related to the trace metals (particularly iron and nickel) provided by the vermicompost. Humic acids, naturally presented in mature vermicompost, also contributed to the enhanced performance of food waste digestion. In summary, manure vermicompost (without any additional chemical amendments) stabilized and increased methane production from anaerobic digestion of food waste in the single-stage digestion system.
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机译：这项研究的总体目标是评估在单一阶段的消化系统中利用ver肥作为添加剂来增强食用后食堂食物垃圾的厌氧消化的有效性，并研究这种增强的机制。选择Vermicompost是因为其具有缓冲能力，丰富的腐殖质和多种微量金属，所有这些都可以增强消化过程。该实验首先使用批处理规模的生化甲烷潜力测定法进行，发现以2 g / L和6 g / L的浓度添加到食物残渣反应器中的ver肥显着提高了最终甲烷产量和甲烷生产率。然后，使用十二个半连续单级反应器进行了长期研究，以确认这种增强作用并进一步研究相关的机理。还评估了比产甲烷活性和痕量金属（铁，镍和钴）的生物利用度。结果表明，不加任何补充物（对照）的食物垃圾消化池具有不稳定的甲烷生成量（每天添加254 mL / g VS，每天破坏455 mL / g VS）。在实验期间，由于挥发性脂肪酸的大量积累（超过2600 mg / L），控制反应器的pH值急剧降低（小于6）。痕量金属的生物利用度测试进一步表明对照蒸煮器可能缺乏镍和铁。相比之下，食物垃圾消化池补充了粪ver（2 g / L），痕量金属（0.01 mg / L镍，0.5 mg / L Fe和0.01 mg / L Co的混合物）或腐殖酸（0.4 g / L）。 L）与对照相比，所有甲烷都有稳定且明显更高的甲烷产量。 pH值约为7，挥发性脂肪酸小于200 mg / L。在所有处理中，辅以ver肥的食物垃圾消化池甲烷产量最高（每天625 mL / g VS被破坏）。与对照相比，补充ver粉还使乙酸盐利用率几乎翻了一番，并使丙酸盐利用率提高了60％。发现这种增强的消化性能可能与the堆提供的痕量金属（尤其是铁和镍）有关。成熟腐殖质中自然存在的腐殖酸也有助于提高食物垃圾消化的性能。总而言之，单级消化系统中粪便的厌氧消化（无任何其他化学修饰）可稳定并增加沼气厌氧消化产生的甲烷。
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