Griffin M E, McMahon K D, Mackie R I, Raskin L
Environmental Engineering and Science, Department of Civil Engineering, 3221 Newmark Civil Engineering Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Biotechnol Bioeng. 1998 Feb 5;57(3):342-55. doi: 10.1002/(sici)1097-0290(19980205)57:3<342::aid-bit11>3.0.co;2-i.
An aggressive start-up strategy was used to initiate codigestion in two anaerobic, continuously mixed bench-top reactors at mesophilic (37 degrees C) and thermophilic (55 degrees C) conditions. The digesters were inoculated with mesophilic anaerobic sewage sludge and cattle manure and were fed a mixture of simulated municipal solid waste and biosolids in proportions that reflect U.S. production rates. The design organic loading rate was 3.1 kg volatile solids/m3/day and the retention time was 20 days. Ribosomal RNA-targeted oligonucleotide probes were used to determine the methanogenic community structure in the inocula and the digesters. Chemical analyses were performed to evaluate digester performance. The aggressive start-up strategy was successful for the thermophilic reactor, despite the use of a mesophilic inoculum. After a short start-up period (20 days), stable performance was observed with high gas production rates (1.52 m3/m3/day), high levels of methane in the biogas (59%), and substantial volatile solids (54%) and cellulose (58%) removals. In contrast, the mesophilic digester did not respond favorably to the start-up method. The concentrations of volatile fatty acids increased dramatically and pH control was difficult. After several weeks of operation, the mesophilic digester became more stable, but propionate levels remained very high. Methanogenic population dynamics correlated well with performance measures. Large fluctuations were observed in methanogenic population levels during the start-up period as volatile fatty acids accumulated and were subsequently consumed. Methanosaeta species were the most abundant methanogens in the inoculum, but their levels decreased rapidly as acetate built up. The increase in acetate levels was paralleled by an increase in Methanosarcina species abundance (up to 11.6 and 4.8% of total ribosomal RNA consisted of Methanosarcina species ribosomal RNA in mesophilic and thermophilic digesters, respectively). Methanobacteriaceae were the most abundant hydrogenotrophic methanogens in both digesters, but their levels were higher in the thermophilic digester.
采用积极的启动策略，在两个中温（37摄氏度）和高温（55摄氏度）条件下的厌氧、连续搅拌台式反应器中启动共消化。消化器接种了中温厌氧污水污泥和牛粪，并以反映美国生产率的比例投喂模拟城市固体废物和生物固体的混合物。设计有机负荷率为3.1千克挥发性固体/立方米/天，停留时间为20天。使用靶向核糖体RNA的寡核苷酸探针来确定接种物和消化器中的产甲烷群落结构。进行化学分析以评估消化器性能。尽管使用了中温接种物，但积极的启动策略对高温反应器是成功的。经过短暂的启动期（20天），观察到稳定的性能，产气率高（1.52立方米/立方米/天），沼气中甲烷含量高（59%），挥发性固体（54%）和纤维素（58%）去除率高。相比之下，中温消化器对启动方法反应不佳。挥发性脂肪酸浓度急剧增加，pH控制困难。经过几周的运行，中温消化器变得更加稳定，但丙酸盐水平仍然很高。产甲烷种群动态与性能指标相关性良好。在启动期间，随着挥发性脂肪酸的积累和随后的消耗，观察到产甲烷种群水平有很大波动。甲烷八叠球菌属是接种物中最丰富的产甲烷菌，但随着乙酸盐的积累，它们的水平迅速下降。乙酸盐水平的增加与甲烷鬃毛菌属丰度的增加平行（在中温和高温消化器中，分别高达总核糖体RNA的11.6%和4.8%由甲烷鬃毛菌属核糖体RNA组成）。甲烷杆菌科是两个消化器中最丰富的氢营养型产甲烷菌，但它们在高温消化器中的水平更高。
