糖浆废水与牛粪厌氧共发酵产甲烷特性研究

Performance of anaerobic co-digestion of molasses wastewater and cattle dung

以糖浆废水和牛粪为底物,采取半连续发酵工艺运行CSTR厌氧发酵系统,考察混合底物中温(35℃)厌氧共发酵产甲烷特性。结果表明:厌氧发酵系统启动后产沼气速率较快,第8 d的沼气产量为350 m L/(L·d),进入稳定期后达到620 m L/(L·d);液相发酵短链挥发性脂肪酸(VFAs)的乙酸含量高于68%。调节进料有机负荷和水力停留时间分别为3.5 g/(L·d)和40 d时,系统运行稳定性与效能最佳,沼气产量为1180 m L/(L·d),甲烷含量高于57%。运用454焦磷酸高通量测序技术分析厌氧发酵系统启动稳定期(40 d)的细菌群落结构和多样性,在细菌属分类水平存在846个OTU,ACE和Chao1分别为2 224.8和1 498.8;Firmicutes门、Proteobacteria门和Bacteroidetes门属优势细菌类群,分别占细菌总数的64.9%,18.2%和9.1%;在属分类水平上,Syntrophomonas sp.为最优势细菌类群,占总丰度的14.5%,其次是Clostridium XI sp.,占总丰度的6.9%。

The anaerobic co-digestion （AD） of molasses wastewater and cattle dung was performed at various process parameters in CSTR system under 35 ℃. The biogas yields increased makedly after start-up period and achieved 350 mL/（ L·d） on 8 day of operation. During a stable time of AD system, biogas production reached 620 mL/（ L·d）, and acetic acid content accounted for more than 68% of total volatile fatty acids （VFAs）. The optimum process of AD system were operated at an organic load rate （OLR） of 3.5 g/（L·d） and a hydraulic retention time （HRT） of 40 d. The optimum biogas yields achieved 1 180 mL/（ L ·d） with a 57% of methane content. Furthermore, 454 pyrosequencing technique was employed to analyze the bacterial diversity on 40 day of operation in AD system. There were 846 OTU obtained at 95% cutoff of sequence similarity, the richness of ACE and Chaol were 2 224.8 and 1 498.8, respectively. The dominant bacteria belonged to Firmicutes （64.9%）, Proteobacteria （18.2%） and Bacteroidetes （9.1%）. At genus level, Syntrophomonas sp. were the most dominant bacteria accounted for 14.5%, and the secondary dominant bacteria were Clostridium XI sp. accounted for 6.9% of total sequences.