Varel V H, Isaacson H R, Bryant M P
Appl Environ Microbiol. 1977 Feb;33(2):298-307. doi: 10.1128/aem.33.2.298-307.1977.
Methane production from waste of cattle fed a finishing diet was investigated, using four 3-liter-working volume anaerobic digestors at 60 degrees C. At 55 degrees C a start-up culture, in which waste was the only source of bacteria, was generated within 8 days and readily adapted to 60 degrees C, where efficiency of methanogenesis was greater. Increasing the temperature from 60 to 65 degrees C tended to drastically lower efficiency. When feed concentrations of volatile solids (VS, organic matter) were increased in steps of 2% after holding for 1 months at a given concentration, the maximum concentrations for efficient fermentation were 8.2, 10.0, 11.6, and 11.6% for the retention times (RT) of 3, 6, 9, and 12 days, respectively. The VS destructions for these and lower feed concentrations were 31 to 37, 36 to 40, 47 to 49 and 51 to 53% for the 3-, 6-, 9-, and 12-day RT digestors, respectively, and the corresponding methane production rates were about 0.16, 0.18, 0.20, and 0.22 liters/day per g of VS in the feed. Gas contained 52 to 57% methane. At the above RT and feed concentrations, alkalinity rose to 5,000 to 7,700 mg of CaCo3 per liter (pH to 7.5 to 7.8), NH3 plus NH4+ to 64 to 90 mM, and total volatile acids to 850 to 2,050 mg/liter as acetate. The 3-day RT digestor was quite stable up to 8.2% feed VS and at this feed concentration produced methane at the very high rate of 4.5 liters/day per liter of digestor. Increasing the percentage of feed VS beyond those values indicated above resulted in greatly decreased organic matter destruction and methane production, variable decrease in pH, and increased alkalinity, ammonia, and total volatile acid concentrations, with propionate being the first to accumulate in large amounts. In a second experiment with another lot of waste, the results were similar. These studies indicate that loading rates can be much higher than those previously thought useful for maximizing methanogenesis from cattle waste.
使用四个工作容积为3升的厌氧消化器，在60摄氏度下研究了育肥牛粪便产生甲烷的情况。在55摄氏度下，以粪便作为唯一细菌来源的启动培养物在8天内生成，并很容易适应60摄氏度，在此温度下甲烷生成效率更高。将温度从60摄氏度提高到65摄氏度往往会大幅降低效率。当在给定浓度下保持1个月后，挥发性固体（VS，即有机物）的进料浓度以2%的步长增加时，对于3、6、9和12天的停留时间（RT），有效发酵的最大浓度分别为8.2%、10.0%、11.6%和11.6%。对于3天、6天、9天和12天停留时间的消化器，这些进料浓度及更低进料浓度下的VS去除率分别为31%至37%、36%至40%、47%至49%和51%至53%，相应的甲烷产生率分别约为每克进料VS每天0.16升、0.18升、0.20升和0.22升。气体中甲烷含量为52%至57%。在上述停留时间和进料浓度下，碱度升至每升5000至7700毫克碳酸钙（pH值为7.5至7.8），NH3加NH4+升至64至90毫摩尔，总挥发性酸以乙酸计升至850至2050毫克/升。3天停留时间的消化器在进料VS高达8.2%时相当稳定，在此进料浓度下，每升消化器每天产生甲烷的速率高达4.5升。将进料VS的百分比增加到上述值以上会导致有机物破坏和甲烷产生大幅减少，pH值可变降低，碱度、氨和总挥发性酸浓度增加，丙酸首先大量积累。在另一批粪便的第二个实验中，结果相似。这些研究表明，负荷率可以比以前认为对牛粪便甲烷生成最大化有用的负荷率高得多。
