The effect of the amount of hydrogen supplied for the in situ biological biogas upgrading was investigated by monitoring the process and evolution of the microbial community. Two parallel reactors, operated at 37°C for 211 days, were continuously fed with sewage sludge at a constant organic loading rate of 1.5 gCOD∙(L∙d)^-1 and hydrogen (H₂). The molar ratio of H₂/CO₂ was progressively increased from 0.5 : 1 to 7 : 1 to convert carbon dioxide (CO₂) into biomethane via hydrogenotrophic methanogenesis. Changes in the biogas composition become statistically different above the stoichiometric H₂/CO₂ ratio (4 : 1). At a H₂/CO₂ ratio of 7 : 1, the methane content in the biogas reached 90%, without adversely affecting degradation of the organic matter. The possibility of selecting, adapting, and enriching the original biomass with target-oriented microorganisms able to biologically convert CO₂ into methane was verified: high throughput sequencing of 16S rRNA gene revealed that hydrogenotrophic methanogens, belonging to Methanolinea and Methanobacterium genera, were dominant. Based on the outcomes of this study, further optimization and engineering of this process is feasible and needed as a means to boost energy recovery from sludge treatment.

中文翻译：

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随着 H2/CO2 比的增加，原位生物沼气升级的性能分析和微生物群落演化

通过监测微生物群落的过程和进化，研究了为原位生物沼气升级提供的氢气量的影响。两个平行反应器在 37°C 下运行 211 天，以 1.5 gCOD∙(L∙d) ^-1和氢气 (H ₂ )的恒定有机负荷率连续加入污水污泥。H ₂ /CO ₂的摩尔比从 0.5:1 逐渐增加到 7:1，以通过氢营养产甲烷作用将二氧化碳 (CO ₂ ) 转化为生物甲烷。高于化学计量的 H ₂ /CO ₂比 (4:1) ，沼气成分的变化在统计上有所不同。在 H ₂/CO ₂比为7:1，沼气中甲烷含量达到90%，对有机物降解没有不利影响。验证了用能够将 CO ₂生物转化为甲烷的靶向微生物选择、适应和富集原始生物质的可能性：16S rRNA 基因的高通量测序显示，氢营养型产甲烷菌，属于Methanolinea和Methanobacterium属，占优势。根据这项研究的结果，该过程的进一步优化和工程化是可行的，并且需要作为提高污泥处理能量回收的手段。