Abstract：
This study presents a bidirectional flow tidal bioreactor designed to enhance H2-driven CO2 biomethanation. The bioreactor alternated biofilms between immersion in nutrient solution and exposure to H2/CO2, creating alternating dry and wet states. This tidal operation minimized liquid film thickness during dry periods and ensured uniform nutrient distribution during wet periods. Bidirectional H2/CO2 supply was used to reduce biofilm thickness heterogeneity across the reactor height. CO2 biomethanation remained stable with an empty bed residence time of 9.7 min, achieving a methane (CH4) formation rate of 26.8 Nm3 CH4/(m3·d). The product gas contained 95.0 ± 2.5 % CH4, with a H2/CO2 conversion efficiency of 90.8 %. Tidal operation mitigated the buildup of dissolved and suspended organics, such as organic acids and detached biofilms. Dominant bacteria in biofilms included fermentative species like Petrimonas and H2-utilizing homoacetogens like Sporomusa. Enriched hydrogenotrophic methanogens, particularly Methanobacterium, were observed. Overall, this study highlights the bioreactor\'s effectiveness in improving CO2 biomethanation.
摘要：
这项研究提出了一种双向流潮汐生物反应器，旨在增强H2驱动的CO2生物甲烷化。生物反应器在浸入营养液和暴露于H2/CO2之间交替生物膜，从而产生交替的干湿状态。这种潮汐操作可最大程度地减少干燥期间的液膜厚度，并确保湿润期间的养分分布均匀。使用双向H2/CO2供应来减少跨反应器高度的生物膜厚度异质性。CO2生物甲烷反应保持稳定,空床停留时间为9.7min,甲烷(CH4)形成速率为26.8Nm3CH4/(m3·d)。产物气体含有95.0±2.5%CH4,H2/CO2转化效率为90.8%。潮汐操作减轻了溶解和悬浮有机物的积聚，如有机酸和分离的生物膜。生物膜中的优势细菌包括发酵物种，如Petrimonas和利用H2的同型乙酸原，如Sporomusa。富含氢营养产甲烷菌，特别是甲烷细菌，被观察到。总的来说,这项研究强调了生物反应器在提高CO2生物甲烷化方面的有效性。
