汽爆柳枝稷乙醇发酵残留物两步厌氧消化研究

TWO-STEP ANAEROBIC DIGESTION OF STILLAGE FROM STEAM-EXPLODED SWITCHGRASS ETHANOL FERMENTATION

为探究木质纤维素乙醇发酵残留物厌氧消化产甲烷性能,以汽爆柳枝稷高底物乙醇发酵残留物为底物,通过甲烷相出水回流至酸化相的方式进行厌氧消化产甲烷研究。结果表明:乙醇发酵残留物可有效进行甲烷生产,通过回流方式,酸化相内过多的挥发酸注入到甲烷相中,甲烷相的出水回流至酸化相,平衡酸化相及甲烷相内的pH值和挥发酸的浓度,提高系统运行稳定性,进而提高厌氧消化效率和甲烷产量。随着甲烷相出水不断地循环至酸化相,甲烷相内的产甲烷菌群也被加入到酸化相内,产甲烷菌群的不断增加、pH值逐渐升高、甲烷含量逐渐上升,使酸化相内产酸菌与产甲烷菌群逐渐趋于平衡,酸化相逐渐向甲烷化发展,并最终转变为产甲烷相。500 mL发酵残留物经厌氧消化,共产生48 L沼气,其中甲烷28.8 L,甲烷产率277 mL/g COD,COD去除率达90%,甲烷含量约60%。

To explore the performance of methane produced by anaerobic digestion of lignocellulosic ethanol fermentation residue, ethanol fermentation stillage of high substrate of steam explosion switchgrass was as the substrate, the methane produced by anaerobic to acidification phase. The results digestion was researched through the way which methane phase effluent was returned demonstrate that ethanol fermentation stillage can effectively produce methane, the recirculation leads excess VFA in the acidogenic reactor transfers to the methanogenic reactor. The recirculation in turn transfers effluent from methanogenic reactor to the acidogenic reactor and balances the pH value and concentration of VFA in two reactors, thus improve the operation stability of the system, the efficiency of anaerobic digestion and yield of methane. Following continuous recirculation of effluent from methanogenic reactor to the acidogenic reactor, the the methanogenic bacteria in the methanogenic reactor is also added to acidogenic reactor, the methanogenic bacteria increases continuously, pH value and methane content rise gradually. The number of acidogenic bacteria and methnogenic bacteria tends to balance, the acidogenic phase is eventually developed to the methanogenic phase. 500 mL fermentation stillage after anaerobic digestion produces 48 L biogas which includes 28.8 L methane, methane yield is 277 mL/g COD, COD removal rate and methane content reach 90% and 60%, respectively.