Abstract：
On-site anaerobic digesters for small agricultural farms typically have feeding schedules that fluctuate according to farm operations. Shocks in feeding, particularly for putrescible waste can disrupt the stable operation of a digester. The effect of intermittent feeding on the anaerobic digestion of rejected raspberries was investigated in four 3L reactors operated in semicontinuous mode for 350 days at 38 °C with a hydraulic retention time of 25 days and an organic loading rate (OLR) of 1gVS/L/d. During the acclimatisation period (147 days) the organic loading was 5 feeds per week. The feeding regime of two reactors was then changed while maintaining the same OLR and HRT to one weekly feed event in one reactor and 3 equal feeds per week in another. The feeding regime did not significantly affect specific methane yield (369 ± 47 L/kgVS on average) despite very different weekly patterns in methane production. Volatile fatty acids (VFA) comprised >83 % of the organics in the effluent, while the rest included non-inhibitory concentrations of phenolic compounds (515-556 mg gallic acid/L). The microbial composition and relative abundance of predominant groups in all reactors were the archaeal genera Methanobacterium and Methanolinea and the bacterial phyla Bacteridota and Firmicutes. Increasing the OLR to 2gVS/L/d on day 238 resulted in failure of all reactors, attributed to the insufficient alkalinity to counterbalance the VFA produced, and the pH decrease below 6. Overall results suggests that optimal digestion of raspberry waste is maintained despite variations in feeding frequency, but acidification can occur with OLR changes.
摘要：
用于小型农业农场的现场厌氧消化器通常具有根据农场操作而波动的饲喂时间表。在喂养的冲击，特别是易腐烂的废物会破坏消化器的稳定运行。在四个3L反应器中以半连续模式在38°C下运行350天，水力停留时间为25天，有机负荷率（OLR）为1gVS/L/d，研究了间歇进料对废弃树莓厌氧消化的影响。在适应期(147天)期间,有机负载为每周5次饲料。然后改变两个反应器的进料方案,同时保持相同的OLR和HRT在一个反应器中每周进料一次,在另一个反应器中每周进料3次。尽管甲烷产量的每周模式差异很大，但进料方式并未显着影响特定的甲烷产量（平均369±47L/kgVS）。挥发性脂肪酸（VFA）占废水中有机物的83％以上，其余包括酚类化合物的非抑制性浓度（515-556mg没食子酸/L）。所有反应器中的微生物组成和主要群体的相对丰度是古细菌甲烷菌和甲醇菌属以及细菌门细菌和Firmicutes。在第238天将OLR提高到2gVS/L/d导致所有反应堆失效，归因于碱度不足以抵消产生的VFA，pH降低到6以下。总体结果表明，尽管喂食频率不同，但仍保持了覆盆子废物的最佳消化，但酸化可随OLR变化而发生。
