Multi-stage microbial system for continuous hydrogen production
View Patent ↗A method of using sequential chemostat culture vessels to provide continuous H 2 production, in which photosynthetic O 2 evolution and H 2 photoproduction are separated physically into two separate bioreactors, comprising: a) growing a microorganism culture able to continuously generate H 2 by photosynthetically producing cells at about the early-to-late log state in a first photobioreactor operating as a sulfur chemostat under aerobic and/or conditions; b) continuously feeding cells from the first photobioreactor to a second photobioreactor operating under anaerobic conditions and sulfur deprivation conditions resulting from constant uptake of sulfate in the first bioreactor and a low rate of culture flow between the first and second bioreactors, for induction of hydrogenase and H 2 photoproduction to allow for continuous cultivation of the microorganism's cells in the first photobioreactor and constant H 2 production in the second photobioreactor, and c) H 2 gas from the second photobioreactor.
1. A method of using sequential chemostat culture vessels to provide continuous H 2 production, in which photosynthetic O 2 evolution and H 2 photoproduction are separated physically into two connected bioreactors, comprising;
a) growing a microorganism culture able to continuously generate H 2 by photosynthetically producing cells at about the early-to-late log state in a first photobioreactor operating as a sulfur chemostat under aerobic and/or anaerobic conditions;
b) continuously feeding cells from the first photobioreactor to a second photobioreactor operating under anaerobic conditions and sulfur deprivation conditions to induce hydrogenase and H 2 photoproduction to provide continuous cultivation of said microorganism's cells in the first photobioreactor and constant H 2 production at a stable rate in the second photobioreactor; and
c) collecting the H 2 gas from the second photobioreactor.
2. The method of clam 1 wherein said microorganism is selected from the group consisting of photosynthetic bacteria, cyanobacteria, and green algae.
3. The method of claim 2 wherein said green algae is Chiamydomonas reinhardtii.
4. The method of claim 3 wherein in step a) said Chiamydomonas reinhardtii is grown under fluorescence illumination.
5. The method of claim 4 wherein subsequent to fluorescence illumination said first photobioreactor is supplied with a continuous addition of a Iris-Acetate-Phosphate (TAP)-sulfur medium containing an amount of sulfate, at a rate sufficient to provide an anaerobic environment.
6. The method of claim 5 wherein, in said anaerobic environment in the first photobioreactor, the rate of photosynthetic O 2 evolution is equal to the approximate rate of respiratory O 2 consumption in cells of said Chiamydomonas reinhardtii.
7. The method of claim 6 wherein, between steps a) and b) continuous feeding of cells produced in said first photobioreactor into said second photobioreactor is commenced after H 2 photoproduction has started in said second reactor.
8. The method of claim 7 wherein, said amount of sulfate, at a rate sufficient to provide an anaerobic environment provides a steady-state chlorophyll (Chl) concentration, no detectable O 2 in said first photobioreactor, and a continuous H 2 photoproduction in said second photobioreactor.
9. The method of claim 1 , wherein H 2 is continuously produced in the second photobioreactor for at least 14 days.