以蔬菜废弃物为原料的厌氧消化系统，由于原料的易酸化特性，在高负荷条件下易失稳，而低负荷的运行会导致较低的池容产气率。本研究采用自行设计的70-L厌氧发酵罐，在中温35℃条件下进行蔬菜废弃物厌氧消化的连续冲击负荷试验，根据气体成分（CH4）的变化规律，添加微量元素（Fe, Co, Ni）以调控消化过程，使其由失稳状态恢复至稳定状态，旨在提高高负荷厌氧发酵的稳定性。研究结果表明，蔬菜废弃物中温厌氧消化系统的有机负荷率增大至2.0 g VS/(L•d)时，CH4含量由50%降至40%，从第103天开始连续添加5天微量元素（Fe, Co, Ni）后，CH4含量迅速恢复至50% ~ 55%的稳定状态，池容产甲烷率由0.38 L/(L•d) 增大至0.6 L/(L•d)左右并保持稳定。停止添加微量元素后，继续增大有机负荷率，厌氧消化系统稳定运行83天。当运行至第195天时（3.0 g VS/(L•d)），CH4含量再次出现下降趋势，由58.9%降至53.4%，添加3天微量元素后，CH4含量再次恢复到55%以上的稳定状态。微量元素的添加可有效提高蔬菜废弃物厌氧消化的稳定性，能够快速恢复失稳的系统。
The anaerobic digestion (AD) system with vegetable waste (VW) as substrate for easy acidification was always operated under low organic loading rate (OLR) with low volumetric methane production rate (VMPR) and then it would result in low efficiency of digester. In this study, continuous AD of VW was carried out in the self-designed 70 L anaerobic reactors under mesophilic conditions (35oC). The trace elements (TE) supplementation was based on the decreasing CH4 content in order to stabilize the process of high OLR for long run-length. When the AD process ran at OLR 2.0 g VS/(L•d) with the CH4 content rapidly decreased from 50% to 40%, through the TE supplementation of 5 days, the CH4 content could quickly return to the stable state 50% ~ 55% from 40%, and VMPR increased from 0.38 L/(L•d) to the stable state of 0.6 L/(L•d). Meanwhile, pH rose from 7.21 to 7.4 and ORP decreased from −509 mV to −530 mV. When the AD process ran at the 20th day of OLR 3.0 g VS/(L•d) after 83 days of the first TE supplementation, the CH4 content decreased from 58.9% to 53.4% again, and then after the TE supplementation of 3 days, the CH4 content could maintain at above 55%. The TE supplementation can effectively improve the OLR and VMPR and stabilize the AD process to increase the utilization of raw materials.
[1] 李崇光, 包玉泽. 我国蔬菜产业发展面临的新问题与对策[J]. 中国蔬菜, 2010, 1(15):1-5.
[2] 刘振东, 李贵春, 杨晓梅,等. 我国农业废弃物资源化利用现状与发展趋势分析[J]. 安徽农业科学, 2012, 40(26): 13068-13070. DOI: 10.13989/j.cnki.0517-6611. 2012.26.10
[3] 董永亮. 果蔬废弃物两相厌氧消化特征研究[J]. 能源环境保护, 2011, 25(4): 19-23, 28. DOI: 10.3969/j.issn. 1006- 8759.2011.04.005.
[4] 张丽颖, 姜永海, 邓舟, 等. 城市生物质废物厌氧消化处理可行性分析[J]. 环境科学与技术, 2010, 33(5): 143-146, 150. DOI: 10.3969/j.issn.1003-6504.2010.05.034.
[5] 郝吉明, 马广大, 王书肖. 大气污染控制工程[M]. 3版. 北京: 高等教育出版社, 2010.
[6] 刘广民, 董永亮, 薛建良, 等. 果蔬废弃物厌氧消化特征及固体减量研究[J]. 环境科学与技术, 2009, 32(3): 27-30, 49. DOI: 10.3969/j.issn.1003-6504.2009.03.007.
[7] 贾传兴, 彭绪亚, 黄媛媛, 等. 有机垃圾厌氧消化系统失稳预警指标的研究进展[J]. 中国给水排水, 2011, 27(24): 30-35.
[8] POLAG D, MAY T, MÜLLER L, et al. Online monitoring of stable carbon isotopes of methane in anaerobic digestion as a new tool for early warning of process instability[J]. Bioresource technology, 2015, 197: 161-170. DOI: 10.1016/ j.biortech.2015.08.058.
[9] EVRANOS B, DEMI?REL B. The impact of Ni, Co and Mo supplementation on methane yield from anaerobic mono- digestion of maize silage[J]. Environmental technology, 2015, 36(12): 1556-1562. DOI: 10.1080/ 09593330.2014.997297.
[10] SCHMIDT T, NELLES M, SCHOLWIN F, et al. Trace element supplementation in the biogas production from wheat stillage-optimization of metal dosing[J]. Bioresource technology, 2014, 168: 80-85. DOI: 10.1016/j.biortech. 2014.02.124.
[11] BANKS C J, ZHANG Y, JIANG Y, et al. Trace element requirements for stable food waste digestion at elevated ammonia concentrations[J]. Bioresource technology, 2012, 104: 127-135. DOI: 10.1016/j.biortech.2011.10.068.
[12] MOESTEDT J, NORDELL E, YEKTA S S, et al. Effects of trace element addition on process stability during anaerobic co-digestion of OFMSW and slaughterhouse waste[J]. Waste management, 2016, 47: 11-20. DOI: 10.1016/j.wasman. 2015.03.007.
[13] FERRY J G. The chemical biology of methanogenesis[J]. Planetary and Space Science, 2010, 58(14/15): 1775-1783. DOI: 10.1016/j.pss.2010.08.014.
[14] GLASS J B, ORPHAN V J. Trace metal requirements for microbial enzymes involved in the production and consumption of methane and nitrous oxide[J]. Frontiers in microbiology, 2012, 3: 61. DOI: 10.3389/fmicb.2012. 00061.
[15] HOCHHEIMER A, HEDDERICH R, THAUER R K. The formylmethanofuran dehydrogenase isoenzymes in Methano- bacterium wolfei and Methanobacterium thermoauto- trophicum: induction of the molybdenum isoenzyme by molybdate and constitutive synthesis of the tungsten isoenzyme[J]. Archives of microbiology, 1998, 170(5): 389-393. DOI: 10.1007/s002030050658.
[16] SHIMA S, WARKENTIN E, THAUER R K, et al. Structure and function of enzymes involved in the methanogenic pathway utilizing carbon dioxide and molecular hydrogen[J]. Journal of bioscience and bioengineering, 2002, 93(6): 519-530. DOI: 10.1016/S1389- 1723(02)80232-8.
[17] LJUNGDHAL L G. The autotrophic pathway of acetate synthesis in acetogenic bacteria[J]. Annual review of microbiology, 1986, 40: 415-450. DOI: 10.1146/ annurev. mi.40.100186.002215.
[18] JARVIS Å, NORDBERG Å, JARLSVIK T, et al. Improvement of a grass-clover silage-fed biogas process by the addition of cobalt[J]. Biomass and bioenergy, 1997, 12(6): 453-460. DOI: 10.1016/S0961-9534(97) 00015-9.
[19] CHOONG Y Y, NORLI I, ABDULLAH A Z, et al. Impacts of trace element supplementation on the performance of anaerobic digestion process: a critical review[J]. Bioresource technology, 2016, 209: 369-379. DOI: 10.1016/j.biortech. 2016.03.028.
