热碱-分步酶水解-厌氧消化工艺处理秸秆畜粪混合物料及其甲烷高值化条件

Performance of Treating Straw and Animal Manure Mixture by an Integrated Process of Thermo-alkali-bi-enzyme Hydrolysis-anaerobic Digestion and Conditions of High Methane Yield

为获得秸秆畜粪混合物料在厌氧消化过程中的甲烷高值化产出,提出了一种新型"热碱-分步酶水解-厌氧消化"组合工艺.以玉米秸秆和牛粪混合物料作为实验对象,考察物料中纤维素、半纤维素、蛋白质获得高溶出效率的热碱预处理条件;分步投加纤维素酶和蛋白酶的剂量及水解时间;热碱预处理后的混合浆液和热碱-酶水解后的混合水解液厌氧消化甲烷产率及产气周期.结果表明,在80℃和0. 5%Na OH碱用量条件下,纤维素、半纤维素和蛋白质的溶出效率(%TS)最高,与未预处理相比(对照组),分别提高24. 84%、12. 24%和8. 92%;分步酶水解的过程和条件为:先投加80 U·g-1的纤维素酶水解18 h,再投加20 U·g-1的蛋白酶水解4 h,纤维素和蛋白质的水解效率可分别达到74. 08%和74. 01%,获得的水解液中糖类提高12～32倍;在厌氧消化阶段,热碱-酶水解后的水解液甲烷产量最高值可达750 m L·h-1,产气周期50 h,相比于热碱预处理后的底物消化(对照组),产甲烷效率提高了约14倍,产气周期缩短了约17 d.热碱-酶水解预处理能有效地解除混合物料厌氧消化过程的水解限速,研究结果可以为开发高效的农业废弃物能源高值化利用技术提供参考依据.

To obtain a high methane yield during the anaerobic digestion of a straw and animal manure mixture,an integrated process of thermo-alkali-bi-enzyme hydrolysis-anaerobic digestion was proposed. A mixture of corn straw and cattle manure was selected as the experimental object. A higher dissolution efficiency of cellulose,hemicellulose,and protein in the thermo-alkali pretreatment,dosages and hydrolysis times of cellulase and protease in the bi-enzyme hydrolysis,and the methane yield and biogas production cycle in the anaerobic digestion with mixed slurry and hydrolysates were investigated respectively. The results showed that the dissolution efficiency( % TS) of cellulose( 24. 84%),hemicellulose( 12. 24%),and protein( 8. 92%) reached their highest levels at 0. 5% Na OH and80℃( compared with the control group). The bi-enzyme hydrolysis process and conditions were as follows: cellulase hydrolysis was 80 U·g-1 and 18 h,and protease hydrolysis was 20 U·g-1 and 4 h. The hydrolysis efficiency of cellulose and protein reached 74. 08%and 74. 01%,respectively. The sugars in the hydrolysate were increased by 12-32 times. During anaerobic digestion,the maximum yield of methane from hydrolysate after thermo-alkali-bi-enzyme hydrolysis was 750 m L·h-1,and the gas production cycle was 50 h.Compared with the mixture after the thermo-alkali pretreatment,the methane production efficiency of the mixed hydrolysate after thermo-alkali-bi-enzyme hydrolysis was increased by 14 times,and the gas production cycle was noticeably shortened by 17 d. The results indicated that the thermo-alkali and enzyme hydrolysis pretreatment could effectively accelerate the hydrolysis rate in the anaerobic digestion with the mixture. The results of this study provide a new reference for developing efficient technology of high-value energy utilization of agricultural waste.