Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.
Biogas Institute of Ministry of Agriculture, Chengdu 610041, China.
Water Res. 2018 Aug 1;139:263-271. doi: 10.1016/j.watres.2018.04.019. Epub 2018 Apr 10.
Effective process monitoring and instability diagnosis are important for stable anaerobic digestion (AD) of vegetable waste (VW). In order to evaluate the performance of thermophilic digestion of VW, to make early diagnosis for instability after organic overload, and to reveal the dynamics of microbial community under different running states, thermophilic AD of VW was carried out under improved organic loading rates (OLR) of 0.5-2.5 g volatile solid (VS)/(L ∙ d) in this study. Gaseous parameters including volumetric methane production rate (VMPR), CH, CO, and H concentrations, and liquid parameters including pH, oxidation-reduction potential, volatile fatty acid (VFA), and total alkalinity (TA), bicarbonate alkalinity (BA), intermediate alkalinity (IA), and ammonia, were monitored. The coupling parameters, such as the CH/CO, VFA/BA, and BA/TA ratios were also used to evaluate stability. The dynamics of syntrophic acetate-oxidizing bacteria (SAOB), acetoclastic methanogens (AM), and hydrogenotrophic methanogens (HM) were analyzed by high-throughput sequencing. The main methanogenic bacteria were HM (Methanothermobacter) during the start-up period of OLR 0.5 gVS/(L ∙ d), while they were AM (Methanosarcina) during the stable period of OLR of 1.0 gVS/(L ∙ d). The VMPR of stable period was about 0.29 L/(L · d) with total VFA concentration below 100 mg/L, CH/CO > 1.3, and BA/TA>0.9. The first instability due to the accumulation of VFA and self-recovery due to syntrophic acetate oxidation occurred at an OLR of 1.5 gVS/(L ∙ d). The syntrophic acetate-oxidizing bacteria probably belong to genus S1 (family Thermotogaceae). The digestion failed at an OLR of 2.0 g VS/(L · d). H was only detected during collapsed period instead of instable period. The total ammonia nitrogen loss and bicarbonate alkalinity (BA) reduction were the primary causes for the instability of AD of VW without effluent recirculation. Compared with single parameters, the CH/CO and BA/total alkalinity (TA) ratios are recommended as early warning indicators for engineering applications of thermophilic AD of VW.
有效过程监测和不稳定性诊断对于稳定的蔬菜废物（VW）厌氧消化（AD）非常重要。为了评估 VW 高温消化的性能，对有机负荷过高后的不稳定性进行早期诊断，并揭示不同运行状态下微生物群落的动态，本研究在改进的有机负荷率（OLR）下进行了 VW 的高温 AD 研究，OLR 为 0.5-2.5 g 挥发性固体（VS）/（L·d）。监测了气态参数，包括体积甲烷产率（VMPR）、CH、CO 和 H 浓度，以及液体参数，包括 pH 值、氧化还原电位、挥发性脂肪酸（VFA）和总碱度（TA）、碳酸氢盐碱度（BA）、中间碱度（IA）和氨。还使用 CH/CO、VFA/BA 和 BA/TA 比等耦合参数来评估稳定性。通过高通量测序分析了产乙酸菌（SAOB）、乙酸分解菌（AM）和氢营养菌（HM）的动态。在 OLR 为 0.5 gVS/（L·d）的启动阶段，主要产甲烷菌为 HM（Methanothermobacter），而在 OLR 为 1.0 gVS/（L·d）的稳定阶段，主要产甲烷菌为 AM（Methanosarcina）。稳定期的 VMPR 约为 0.29 L/（L·d），总 VFA 浓度低于 100 mg/L，CH/CO>1.3，BA/TA>0.9。在 OLR 为 1.5 gVS/（L·d）时，由于 VFA 积累而首次出现不稳定性，并由于乙酸共氧化而自我恢复。产乙酸菌可能属于 S1 属（Thermotogaceae 科）。当 OLR 为 2.0 g VS/（L·d）时，消化失败。在崩溃期而不是不稳定期仅检测到 H。没有出水回流的 VW AD 不稳定性的主要原因是总氨氮损失和碳酸氢盐碱度（BA）减少。与单一参数相比，CH/CO 和 BA/总碱度（TA）比被推荐为 VW 高温 AD 工程应用的早期预警指标。
