We investigated the feasibility of producing biogas in a fixed-bed anaerobic reactor at 4 °C with a gradual increase in organic loading rate (OLR). Reactor efficiency was highest when OLR was 4.33 kg/m3·d, whereas the reactor acidification occurred when OLR was 4.67 kg/m3·d. The values of methane content, biogas production, chemical oxygen demand (COD) removal rate, biogas production rate, acetic acid content, and propionic acid content were 69.3%, 5.33 L, 59.8%, 1.03 L/OLR, 0.17 g/L, and 1.15 g/L, respectively. The pH was stable and ranged from 7.2 to 6.8 when the reactor was operating at 4 °C during OLR increase. The 16S rRNA gene analysis revealed that the dominant archaea were Methanosaetaceae at 30 °C. At 4 °C, the dominant archaea were Methanomicrobiales, which were more abundant in adhering sludge compared to settled sludge. In conclusion, operating a fixed-bed anaerobic reactor at psychrophilic temperatures is more suitable.

中文翻译：

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4 °C 下有机负载率对固定床厌氧反应器性能和产甲烷微生物群落的影响

我们研究了在 4°C 下在固定床厌氧反应器中生产沼气的可行性，并逐渐增加有机负荷率 (OLR)。当OLR为4.33 kg/m3·d时反应器效率最高，而OLR为4.67 kg/m3·d时反应器发生酸化。甲烷含量、沼气产量、化学需氧量（COD）去除率、沼气产量、乙酸含量、丙酸含量分别为69.3%、5.33 L、59.8%、1.03 L/OLR、0.17 g/L、和 1.15 克/升，分别。当反应器在 OLR 增加期间在 4°C 下运行时，pH 值是稳定的，范围从 7.2 到 6.8。16S rRNA基因分析显示，30℃下优势古菌为甲烷菌科。在 4 °C 时，主要的古菌是甲烷微生物，与沉降污泥相比，它们在粘附污泥中更丰富。综上所述，