Enhanced bio-production from CO2 by microbial electrosynthesis (MES) with continuous operational mode.
Enhanced bio-production from CO2 by microbial electrosynthesis (MES) with continuous operational mode.
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DOI：
10.1039/d0fd00132e
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发表时间：
2021-01
影响因子：
3.4
通讯作者：
P. Izadi;Jean-Marie Fontmorin;Swee Su Lim;I. Head;E. Yu
中科院分区：
文献类型：
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作者：
P. Izadi;Jean-Marie Fontmorin;Swee Su Lim;I. Head;E. Yu
由于减少温室气体排放和化学品生产的去甲烷化的迫切需要，能够将CO2转化为燃料和化学品的各种原料的技术正在出现。微生物电合成（MES）是一种利用微生物和电子合成有机产品，特别是乙酸酯的有前途的技术。然而，该系统的效率较低。在这项研究中，我们证明了简单而有效的策略，提高MES的效率，通过应用连续进料制度。与补料分批系统相比，连续操作模式提供了更好的pH控制和恒定的培养基更新，当阴极电位为-1.0 V Ag/AgCl和溶解的CO2时，乙酸生产率更高，生物产物更多样化。水力停留时间（HRT）对产酸模式、产酸速率和库仑效率有直接影响。水力停留时间为3d时，pH值为5.2左右，乙酸盐为主要产物，最高产率为651.8 ± 214.2ppm/d，库仑效率为90%。然而，在7天的HRT下，pH较低，约为4.5，并且获得了较低但稳定的乙酸盐生产速率，为每天280 ppm，最大库仑效率为80%。此外，更多样化和更长的链的产品，如丁酸，异戊酸和己酸，检测到低浓度仅在HRT的7天。尽管微生物群落分析显示了在将补料分批模式切换为连续补料模式后，反硝化细胞群落的变化，但乙酸杆菌仍然是CO2还原为乙酸盐的负责细菌，主导阴极生物膜。
Technologies able to convert CO2 to various feedstocks for fuels and chemicals are emerging due to the urge of reducing greenhouse gas emissions and de-fossilizing chemical production. Microbial electrosynthesis (MES) has been shown a promising technique to synthesize organic products particularly acetate using microorganisms and electrons. However, the efficiency of the system is low. In this study, we demonstrated the simple yet efficient strategy in enhancing the efficiency of MES by applying continuous feeding regime. Compared to the fed-batch system, continuous operational mode provided better control of pH and constant medium refreshment, resulting in higher acetate production rate and more diverse bio-products, when the cathodic potential of -1.0 V Ag/AgCl and dissolved CO2 were provided. It was observed that hydraulic retention time (HRT) had a direct effect on the pattern of production, acetate production rate and coulombic efficiency. At HRT of 3 days, pH was around 5.2 and acetate was the dominant product with the highest production rate of 651.8 ± 214.2 ppm per day and a significant coulombic efficiency of 90%. However at the HRT of 7 days, pH was lower at around 4.5, and lower but stable acetate production rate of 280 ppm per day and a maximum coulombic efficiency of 80% was obtained. In addition, more diverse and longer chain products, such as butyrate, isovalerate and caproate, were detected with low concentrations only at the HRT of 7 days. Although microbial community analysis showed the change in the planktonic cells communities after switching the fed-batch mode to continuous feeding regime, Acetobacterium still remained as the responsible bacteria for CO2 reduction to acetate, dominating the cathodic biofilm.