搅拌强度对“两相分区一体”沼气发酵工艺产气效率的影响

Effect of stirring intensity on integrated two-phase biogas digestion

为探讨纤维素原料沼气发酵中立式发酵罐易形成浮渣、进料量多容易酸败等瓶颈问题的解决途径,开发了高径比为3.5的"两相分区一体"新工艺装置,对新鲜及青贮玉米秸秆的发酵体系中上部酸化相、下部产甲烷相在微搅拌和每日定时强搅拌2种工艺下的产气效率和各种发酵参数进行了动态测定。结果表明,微搅拌条件下的原料产甲烷潜力高于强搅拌;2种搅拌强度下,鲜秸秆的产甲烷潜力均高于青贮秸秆。在立式反应器中,挥发性有机酸(VFA)质量浓度、可溶性化学需氧量(SCOD)、pH及产甲烷菌和细菌的数量上下明显分层,形成鲜明的"两相分区一体"发酵体系,实现了在同一空间的不同区域分别行使着分解产酸和产甲烷的2种功能。

The easily generation of scum and acidified system caused by largely fed feedstock in vertical reactors has been the bottleneck problem about lignocellulosic materials biogas digestion. Integrated two-phase anaerobic reactor （ITPAR） with height-diameter ratio 3.5 composed by upper and lower space acting as acidogenic and methanogenic phases, respectively, was developed in this study. The biogas production efficiency and fermentation parameters dynamic based on fresh and silage cornstalk digestion were determined comparatively. The tests were conducted by using two identical ITPARs： One was stirred slightly （R1） and the other one was stirred vigorously （R2） at regular time each day. The results showed that=The methane yields of each kind of cornstalk obtained from R1 were higher than those from R2. The methane yields of fresh cornstalk obtained from two reactors were both higher than those of silage cornstalk. Volatile fatty acids concentrations, soluble chemical oxygen demand, pH, and acidogenic and methanogenic community differed in upper and lower phases in these vertical reactors, forming an obvious integrated two-phase fermentation system. The hydrolysis and methanogenesis occurred at different phases in the same space.