低温冻融-酶解预处理对稻秆厌氧发酵产气特性的影响

摘要

为利用我国寒冷地区天然冷资源,在实验室模拟低温环境(Z组:-4℃,S组:-20℃),探索低温冻融及纤维素酶液预处理对水稻秸秆中温厌氧发酵产气特性的影响.结果表明,浸泡温度30℃、浸泡时间4h、液固比15 mL/g条件下水稻秸秆持水力最佳.冷冻后解冻液中木糖质量(Z3组:6.5g,S2组:7.2g)大幅增加,半纤维素转化率(Z3组:24.1％,S2组:26.6％)增幅显著(p＜0.05).经纤维素酶解后其水解液中葡萄糖质量(Z3组:13.5g,S2组:14.5 g)大幅增加,纤维素转化率(Z3组:30.9％,S2组:33.2％)增幅显著(p＜0.05).对预处理后的原料进行厌氧发酵,累计产气量最高543 mL,较CK提升73.5％(S4组),平均甲烷体积分数最高提升160.4％(S2组),且随着冷冻时间的延长(Z组48 h以上,S组24 h以上)厌氧发酵周期缩短(共19d),产气高峰提早到来且峰值较高.过酸化现象得到有效缓解,能够更快地进入到甲烷化阶段.%In order to use of the outdoor cold climate resources as the low-temperature reaction condition,the objective of this research was to investigate the effect of freeze-thaw treatment (Z groups:-4℃,S groups:-20℃) on the efficiency of hemicellulose degradation and enzymatic hydrolysis pretreatment of rice straw to improve its biodegradability and anaerobic biogas production.A new low temperature freeze-thaw pretreatment development pathway was created for the pre-processing research and development.The results showed that water holding capacity was optimal when soaking temperature was 30℃,time was 4 h,and liquid-solid ratio was 15 mL/g.Under low temperature freeze-thaw condition,the contents of xylose in the liquid hydrolysates were increased (Z3:6.5 g,S2:7.2 g),hemicellulose conversion rate reached 24.1％ (Z3) and 26.6％ (S2),which were improved significantly(p ＜ 0.05).Glucose yield were increased (Z3:13.5 g,S2:14.5 g) after enzymatic hydrolysis,cellulose conversion rate reached 30.9％ (Z3) and 33.2％ (S2),which were improved significantly (p ＜ 0.05).These treatments conditions resulted in the highest total biogas yield (543 mL,S4),compared with the CK,the total biogas yield from S4 was improved by 73.5％.The highest average methane concentrations level was 51.3％ (S2),compared with CK,it was improved by 160.4％ (S2).Extension of time for freeze was apt to shorten the anaerobic fermentation period in the next anaerobic digestion.The digestion time for pretreatment rice straw (Z groups freeze-thaw treatment time was above 48 h,S groups freeze-thaw treatment time was above 24 h) was calculated as 19 d,and the peak values of gas production came earlier than those of other groups.The significant reduction in digestion time indicated that the straw had become more accessible and more readily biodegradable after biological pretreatment.Freeze-thaw and enzymatic pretreatment could be an effective method for improving biodegradability and enhancing the highly efficient biological conversion of rice straw into bioenergy.