Effects of voltage application on hydrogen production performance and stabilization in an electro-supported dynamic membrane bioreactor

Introduction A novel electro-supported dynamic membrane bioreactor (EDMBR) was by integrating electrode function into a dynamic membrane module made of a stainless steel mesh support with a pore size of 444 mm. This work aimed to investigate the effects of voltage application on stabilization time, hydrogen production performance, metabolic pathway shift, and microbial community change during continuous hydrogen production. Methods Two independent EDMBR systems were operated under continuous conditions at different applied voltages ranging from 30 to 700 mV. Hydrogen production performance, soluble byproducts, suspended biomass, biofilm concentration, and microbial community were analyzed under different operational conditions. Results Voltage application in the EDMBR influenced both process stabilization and biological responses during continuous biohydrogen production. Electrical input was associated with accelerated stabilization time through improved biomass retention, whereas sustained voltage application was related to a shift in metabolic pathways and changes in microbial community. Voltage application reduced the stabilization time required to reach pseudo-steady-state from 8 days to 3 days. However, excessive electrical input was associated with decreased hydrogen production performance and localized corrosion of the electro-supported mesh under elevated current density conditions. Discussion These results indicate a trade-off between rapid stabilization and hydrogen production performance under voltage application, suggesting that electrical input should be strategically managed rather than continuously intensified. An operational window from 0.30 to 1.21 mA/cm 2 was identified to balance rapid stabilization with hydrogen production performance while minimizing the risk of corrosion and reactor deterioration. Within this range, voltage application can be applied to restore pseudo-steady-state following reactor deterioration. However, excessive electrical input may increase the risk of metabolic pathway shifts and long-term performance decline. Therefore, further studies are recommended to develop operational strategies that maintain metabolic flux toward H2-producing pathways and preserve the dominance of H2-producing bacteria during continuous EDMBR operation.