The experiments were carried out in continuous flow acidogenic reactors with molasses used as substrate to study the effects of pH and redox potential on fermentation types. The conditions for each fermentation type w...The experiments were carried out in continuous flow acidogenic reactors with molasses used as substrate to study the effects of pH and redox potential on fermentation types. The conditions for each fermentation type were investigated at different experimental stages of start up, pH regulating and redox potential regulating. The experiments confirmed that butyric acid type fermentation would occur at pH > 6, the propionic acid type fermentation at pH about 5.5 with E h> -278 mV, and the ethanol type fermentation at pH < 4.5. A higher redox potential will lead to propionic acid type fermentation because propionogens are facultative anaerobic bacteria.展开更多
Dark fermentation is a biological process that converts organic molecules into molecular hydrogen and stands out as one of the most promising methods for extracting bioenergy from wastewater.The accumulation of endpro...Dark fermentation is a biological process that converts organic molecules into molecular hydrogen and stands out as one of the most promising methods for extracting bioenergy from wastewater.The accumulation of endproducts causes varying inhibitory effects on the process,posing a key challenge.This study explored the efficacy and mechanisms of biochar as a cost-effective solution to mitigating the inhibitory effects of end-products in major types of dark fermentative hydrogen production processes and provided for the first time a quantitative analysis of the relative contribution of each mechanistic pathway.Results showed that biochar was more effective in butyratetype than ethanol-type fermentations.In butyrate-type fermentation facing endogenous and exogenous volatile acid inhibition,biochar increased hydrogen production by 145.74%and 64.95%,respectively.In ethanol-type fermentation,biochar increased hydrogen production by 10.53%and 18.09%under endogenous and exogenous inhibitions from ethanol,respectively.Mechanistic analyses revealed three primary pathways through which biochar mitigated product inhibition:pH buffering,cell colonization,and inhibitor adsorption.The relative contribution of each pathway varied by fermentation type.In butyrate-type fermentation,pH buffering was critical,accounting for 42.9%of the mitigation effect,while cell colonization was primary in ethanol-type fermentation,contributing 32.4%.This study demonstrated the different roles of biochar in mitigating production inhibition in diverse fermentation types,highlighting its potential to enhance hydrogen energy recovery in dark fermentation.展开更多
文摘The experiments were carried out in continuous flow acidogenic reactors with molasses used as substrate to study the effects of pH and redox potential on fermentation types. The conditions for each fermentation type were investigated at different experimental stages of start up, pH regulating and redox potential regulating. The experiments confirmed that butyric acid type fermentation would occur at pH > 6, the propionic acid type fermentation at pH about 5.5 with E h> -278 mV, and the ethanol type fermentation at pH < 4.5. A higher redox potential will lead to propionic acid type fermentation because propionogens are facultative anaerobic bacteria.
基金supported by the National Key R&D Program of China(Grant No.2024YFD1501303)National Natural Science Foundation of China(Grant No.42477248,52200041)+2 种基金CAS Pioneer Hundred Talents Program,Natural Science Foundation for Excellent Young Scholars of Liaoning Province(No.2024JH3/10200025)the Liaoning Revitalization Talents Program(XLYC2007192)the Youth Innovation Promotion Association CAS(2020200).
文摘Dark fermentation is a biological process that converts organic molecules into molecular hydrogen and stands out as one of the most promising methods for extracting bioenergy from wastewater.The accumulation of endproducts causes varying inhibitory effects on the process,posing a key challenge.This study explored the efficacy and mechanisms of biochar as a cost-effective solution to mitigating the inhibitory effects of end-products in major types of dark fermentative hydrogen production processes and provided for the first time a quantitative analysis of the relative contribution of each mechanistic pathway.Results showed that biochar was more effective in butyratetype than ethanol-type fermentations.In butyrate-type fermentation facing endogenous and exogenous volatile acid inhibition,biochar increased hydrogen production by 145.74%and 64.95%,respectively.In ethanol-type fermentation,biochar increased hydrogen production by 10.53%and 18.09%under endogenous and exogenous inhibitions from ethanol,respectively.Mechanistic analyses revealed three primary pathways through which biochar mitigated product inhibition:pH buffering,cell colonization,and inhibitor adsorption.The relative contribution of each pathway varied by fermentation type.In butyrate-type fermentation,pH buffering was critical,accounting for 42.9%of the mitigation effect,while cell colonization was primary in ethanol-type fermentation,contributing 32.4%.This study demonstrated the different roles of biochar in mitigating production inhibition in diverse fermentation types,highlighting its potential to enhance hydrogen energy recovery in dark fermentation.
