沼液回流提升推流式厌氧反应器运行效果研究

为了研究沼液回流对推流式厌氧反应器(PFR)厌氧消化效率的影响,文章采用有效容积为36 L的PFR,以牛粪为底物,进料浓度TS为7~10%,发酵温度38℃±1℃,水力停留时(HRT)为20 d条件下连续运行100 d。结果发现:50%的沼液回流能够提升反应器产气效率,在沼液回流运行期,日产气量最高达到57.92 L·d^-1,容积产气率为1.58 L·L^-1d^-1,甲烷含量为68.9%。平均挥发性有机物产气率为433.03 L·kg^-1 VS(干物质产气率为366.99 L·kg^-1 TS),相比于未回流沼液运行期提升42.46%,底物转化效率提高了17.84%。通过对沼液回流运行期的微生物群落组成分析可以看出,细菌主要以Firmicutes和Bacteroidetes具有降解纤维类及大分子的水解酸化菌为主。古菌则以Methanothrix和Methanospirillum为绝对的优势产甲烷菌为主。该研究结果可为以牛粪为原料的大型沼气工程提高整体效率和能量输出提供基础参考数据。

Biogas Slurry Reflux Promotes the Operation of the Plug-flow Anaerobic Reactor

To evaluate the effect of biogas slurry reflux on the anaerobic digestion efficiency of plug flow reactor(PFR),in this paper,a PFR with an effective volume of 36 L was adopted with cow dung as the substrate.The feed concentration of TS was 7%~10%;the fermentation temperature was 38℃±1℃.The PFR continuously operated for 100 days at the hydraulic retention(HRT)of 20 d.The result showed that 50%biogas slurry reflux could improve the gas production efficiency of the reactor.The maximum daily biogas production reached 57.92 L·d^-1,the volumetric biogas production rate was 1.58 L·L^-1,and the methane content was 68.9%.The average specific biogas yield of substrate was 433.03 L·kg^-1VS(366.99 L·kg^-1 TS),which was 42.46%higher than the control without reflux of biogas slurry.Moreover,the conversion efficiency of substrate was improved by 17.84%.Through the analysis of the microbial community composition during the biogas slurry backflow operation,the bacteria were mainly hydrolytic acidizing bacteria with the function of degrading fibers and macromolecules,mainly Firmicutes and Bacteroidetes.The archaea was dominated by methanogens genera Methanothrix and Methanospirillum.