Abstract: To investigate effects of mechanical stirring intensity on the biogas production characteristics and fermentation stability of cattle manure and corn straw anaerobic co-digestion and determine the optimum stirring intensity,experiments with cattle manure and corn straw(volatile solid ratio of 7∶3) as fermentation materials at different stirring intensity of 0(the control treatment),30,60,90 r/min were conducted under the conditions of 7% volatile solid and (35±1)℃ .The results showed that the biogas production and potential volatile solid methane production were increased firstly and then decreased with the increase of stirring intensity. When the stirring intensity was 60 r/min, the cumulative biogas production,total methane production and volatile solid methane production were higher than other treatments,reaching 120.67,71.44 L and 194.39 mL/g,which were 10.0%,9.9%,9.9% higher than that of the control treatment,respectively.No significant differences were observed in methane content (60%—63%) among different stirring intensity treatments.The pH value maintained between 6.60—7.30 and the ratio of volatile fatty and alkalinity was below 0.4 for all treatments,showing the stability of the anaerobic fermentation systems.Lower ratios of volatile fatty and alkalinity for stirring treatments than the control treatment showed that stirring could reduce the ratio of volatile fatty and alkalinity of biogas slurry and enhance the stability of anaerobic fermentation systems. Based on comprehensive consideration of biogas production and stability of anaerobic fermentation system,the optimal stirring intensity was 60 r/min.

Key words: Mechanical stirring intensity, Cattle manure, Corn straw, Anaerobic fermentation, Codigestion;Biogas production characteristics, System stability

摘要： 为探索机械搅拌强度对牛粪与玉米秸秆混合厌氧发酵产气性能和系统稳定性的影响，确立牛粪与玉米秸秆混合厌氧发酵适宜的搅拌强度，将牛粪和玉米秸秆按照挥发性固体（VS）质量比7∶3进行配混，在物料VS质量分数7%、发酵温度（35±1）℃条件下，进行30、60、90 r/min不同机械搅拌强度的厌氧发酵产气试验，以不搅拌的处理为对照。结果表明，牛粪与玉米秸秆混合厌氧发酵产沼气量和VS产甲烷量随搅拌强度的提高呈先升高后降低的趋势。当搅拌强度为60 r/min时，产气性能最好，累积产沼气量、甲烷总产量和VS产甲烷量均较高，分别达120.67、71.44 L和194.39 mL/g，分别较对照高出10.0%、9.9%、9.9%，各处理平均甲烷含量为60%~63%，无明显差异。反应过程中，各处理pH值始终维持在6.60～7.30，VFA/碱度值小于0.4，厌氧发酵系统均能稳定运行。但是搅拌处理的VFA/碱度值均低于对照，说明搅拌可降低发酵料液的VFA/碱度值，增强厌氧发酵系统的稳定性。因此，从产气量和系统稳定性综合考虑，适宜的搅拌强度为60 r/min。

关键词: 机械搅拌强度, 牛粪, 玉米秸秆, 厌氧发酵, 混合发酵, 产气性能, 系统稳定性