Vegetable waste (VW) is highly perishable and susceptible to acidification during anaerobic digestion, which inhibits biogas production. Effective process monitoring, diagnosis and control are necessary to maintain stable anaerobic digestion at a high organic loading rate (OLR). Continuous mesophilic digestion was conducted at OLRs of 0.5, 1.0, 1.5, 2.0, 3.0, 3.5 and 4.0 g volatile solids (VS)/(L d) with effluent recirculation (ER) in a reactor with total volume of 70 L. The effectiveness of three early warning indicators was validated. The ability of trace elements (TEs) (Fe, Co and Ni) to recover unstable VW digestion systems was evaluated. The results showed that the ratio of bicarbonate alkalinity (BA) to total alkalinity (TA) was a more effective warning indicator than the ratios of methane (CH₄) to carbon dioxide and volatile fatty acids (VFAs) to TA. When the ratio of BA/TA was lower than 0.9, the digestion system tended to be unstable. ER maintained a stable OLR of 1.5 g VS/(L d). The addition of TEs achieved a maximum stable OLR of 3.5 g VS/(L d) with an average volumetric biogas production rate of 1.91 L/(L d). Severe VFAs accumulation and unrecoverable instability occurred at an OLR of 4.0 g VS/(L d). The supplementation of ammonium bicarbonate was not useful for the recovery of the unstable system when the OLR was greater than 3.5 g VS/(L d) for the digestion of VW. The specific methane production was approximately 340 L/kg VS during the stable period with a digestion efficiency of 85%.

中文翻译：

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通过使用碳酸氢盐碱度与总碱度之比添加微量元素作为早期预警指标来恢复蔬菜废弃物的不稳定消化。

蔬菜废弃物（VW）极易腐烂，在厌氧消化过程中易酸化，从而抑制了沼气的产生。有效的过程监控，诊断和控制对于在高有机负荷率（OLR）下维持稳定的厌氧消化至关重要。在总体积为70 L的反应器中，以0.5 g，1.0 g，1.5 g，2.0 g，3.0 g，3.5 g和4.0 g挥发性固体（VS）/（L d）的OLR进行连续中温消化。三个预警指标中的一个已经过验证。评估了痕量元素（TEs）（铁，钴和镍）恢复不稳定的大众消化系统的能力。结果表明，碳酸氢盐碱度（BA）与总碱度（TA）的比率比甲烷（CH ₄）转化为二氧化碳，并将挥发性脂肪酸（VFA）转化为TA。当BA / TA之比低于0.9时，消化系统趋于不稳定。ER维持1.5 g VS /（L d）的稳定OLR。TE的添加实现了3.5 g VS /（L d）的最大稳定OLR，平均沼气生产量为1.91 L /（L d）。在4.0 g VS /（L d）的OLR时发生严重的VFA积累和不可恢复的不稳定。当OLR大于3.5 g VS /（L d）进行VW消化时，补充碳酸氢铵不能用于不稳定系统的回收。在稳定时期，特定的甲烷产量约为340 L / kg V​​S，消化效率为85％。