Electro-extractive fermentation for efficient biohydrogen production

Abstract

Electrodialysis, an electrochemical membrane technique, was found to prolong and enhance the production of biohydrogen and purified organic acids via the anaerobic fermentation of glucose by Escherichia coli. Through the design of a model electrodialysis medium using cationic buffer, pH was precisely controlled electrokinetically, i.e. by the regulated extraction of acidic products with coulombic efficiencies of organic acid recovery in the range 50-70% maintained over continuous 30-day experiments. Contrary to previous reports, E. coli produced H 2 after aerobic growth in minimal medium without inducers and with a mixture of organic acids dominated by butyrate. The selective separation of organic acids from fermentation provides a potential nitrogen-free carbon source for further biohydrogen production in a parallel photofermentation. A parallel study incorporated this fermentation system into an integrated biohydrogen refinery (IBR) for the conversion of organic waste to hydrogen and energy.

Lignocellulose biohydrogen: Practical challenges and recent progress

“…In the removal of fermentation inhibitors, an interesting concept, referred as Integrated Biohydrogen Refinery [61] may stand as a way forward. This strategy involves so-called electro-extractive fermentation [62] which, in principles, combines bacterial hydrogen production with a membrane process: electrodialysis. This application enables the user to regulate pH by separation of organic acids -formed as secondary metabolic products -from the culture media and hence prolong efficient hydrogen production activity.…”

Electro-Fermentation in Aid of Bioenergy and Biopolymers

“…Similarly, an electrodialysis system was used to extract the organic acids produced during dark fermentation of glucose for H 2 production by Escherichia coli. The extracted organics were later used as a potential nitrogen free carbon source for photo-fermentative H 2 production by Rhodobacter sphaeroides [111]. Later, this process was successfully demonstrated on food waste hydrolysates [112].…”

Removal and recovery of inhibitory volatile fatty acids from mixed acid fermentations by conventional electrodialysis

“…Theoretically, it is possible to produce 4 mol H 2 ·mol -1 hexose sugar when acetic acid is the only product Studies have demonstrated that reducing the concentrations of acetic acid and n-butyric acid in hydrogen fermentation broths, via bipolar membrane electrodialysis, increases hydrogen yields (Redwood et al, 2012a(Redwood et al, , 2012bTang et al, 2014). Bipolar membrane electrodialysis is one of several electrodeionisation and electrodialysis processes, the majority of which were described by Huang et al (Huang et al, 2007).…”

“…Bipolar membrane electrodialysis requires expensive, bipolar, water-splitting, membranes in order to work and reported increases in hydrogen yield using glucose as a substrate are inconsistent. For example, Tang et al (Tang et al, 2014) report an increase from 1.7 to 2.2 mol H 2 ·mol -1 glucose, whereas Redwood et al (Redwood et al, 2012b) claim that the removal of organic acids via bipolar membrane electrodialysis prolongs fermentation time from 3 days to 3 weeks, tripling H 2 production in doing so from 1 to 3 mol H 2 ·mol -1 glucose. More recent work used activated carbon as a means to extract inhibitory byproducts from hydrogen reactors fed by water hyacinth, and increased hydrogen yields from 124.9 ml H 2 ·g -1 total volatile solids to 134.9 ml H 2 ·g -1 total volatile solids (Cheng et al, 2015).…”