Resistance assessment of microbial electrosynthesis for biochemical production to changes in delivery methods and CO2 flow rates

Abstract

Microbial electrosynthesis (MES) for CO2 valorization could be influenced by fluctuations in CO2 mass transfer and flow rates. In this study, we developed an efficient method for CO2 delivery to cathodic biofilm by directly sparging CO2 through the pores of ceramic hollow fiber wrapped with Ni-foam/carbon nanotube electrode, and obtained 45% and 77% higher acetate and methane production, respectively. This was followed by the MES stability test in response to fluctuations in CO2 flow rates varying from 0.3 ml/min to 10 ml/min. The biochemical production exhibited an increasing trend with CO2 flow rates, achieving higher acetate (47.0 ± 18.4 mmol/m 2 /day) and methane (240.0 ± 32.2 mmol/m 2 /day) generation at 10 ml/min with over 90% coulombic efficiency. The biofilm and suspended biomass, however, showed high resistance to CO2 flow fluctuations with Methanobacterium and Acetobacterium accounting for 80% of the total microbial community, which suggests the robustness of MES for onsite carbon conversion.

Microbial electrosynthesis of acetate from CO2 under hypersaline conditions

“…The current density was calculated as the amount of electric current flowing per projected cathode surface area [ 6 ]. The coulombic efficiency (CE, %) of the cathodes for cumulative VFA and H 2 production and the CO 2 consumption rate, , were calculated based on prior work [ 20 , [22] , [23] , [24] ], shown as follows. Here, and are the moles of the VFAs and H 2 produced at time t , is the molar conversion factor of produced VFA (it is 2 for formate, 8 for acetate, 14 for propionate, and 20 for butyrate and isobutyrate), I is the current (A), and F is Faraday's constant (96,485 C mol −1 ).…”

Long-Term Continuous Extraction of Medium-Chain Carboxylates by Pertraction With Submerged Hollow-Fiber Membranes

“…Genomic DNA extraction, DNA amplification, and sequencing were performed according to the protocol in a previous study (Alqahtani et al, 2021). Operational taxonomic unit (OTU) abundance was estimated at 97 identities using the usearch (v. 7.0.1090-usearch_global) (Bian et al, 2021). Taxonomy was assigned to representative OTUs using the RDP classifier in QIIME (Caporaso et al, 2010).…”

Biofilm matrix and artificial mediator for efficient electron transport in CO2 microbial electrosynthesis

“…On the other hand, electrode surface area-dependent bioconversion like MES still has the drawbacks of a low volumetric production rate and titer and stability. Recently, some research groups reported stable MES performance against power supply interruption and influent CO 2 flow fluctuation [7,28]. Nevertheless, these drawbacks need to be resolved before industrial and field-scale applications can be achieved [8].…”