Hyperthermophilic Hydrogen Production from Cattle Manure by Two-Stage Dark Fermentation and Microbial Electrolysis Cell

Date

2023-8-24

Author

Tunca, Berivan

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The objective of this study is to implement an efficient two-stage DF and MEC system operation to produce hydrogen from unpretreated cattle manure (UCM) at hyperthermophilic temperatures. In the first part of this thesis, the DF of UCM at high loadings (up to 50 g volatile solids (VS)/L) by hyperthermophilic cellulolytic bacterium Caldicellulosiruptor bescii was studied in batch reactors operated at 75 oC. To increase the yield and the rate of H2 production, the impact of intermittent gas sparging and adaptation of inoculum were investigated. The results revealed that adaptation strategy has a superior effect on biohydrogen production. The highest hydrogen yield was achieved with the adapted culture as 161.3 mL H2/g VSadded at 15 g VS/L UCM and the maximum hydrogen production rate was 7.77 mL H2/mL/h at 25 g VS/L of UCM. In the second part of the thesis, bioelectrochemical hydrogen production from fermentation effluent, rich in acetate, was studied in MEC at 80 oC using hyperthermophilic electro-active archaea. The experimental work included the selection of inoculum for hyperthermophilic MECs and electrode material for biofilm formation. Further, the utilization of DF effluent in single chamber MECs were studied to enhance the hydrogen production by Geoglobus acetivorans and finally adaptation strategy similar to the first part was used for performance enhancement. Hydrogen production rate (0.52 ± 0.07 m3 H2/m3d) was successfully increased by 11.5 times via the use of adapted culture compared to the acetate-grown wild type culture (and 0.05 ± 0.02 m3 H2/m3d). A variety of biofilm imaging analyses such as confocal laser scanning and scanning electron microscopy were conducted to study the viability of the adapted culture biofilm. This study demonstrates the promising potential of a two-stage hyperthermophilic DF and MEC process for hydrogen production from UCM, achieving a significant hydrogen yield of 506.8 mL H2/g VSadded.

Subject Keywords

Dark fermentation (DF), Microbial electrolysis cell (MEC), Culture adaptation, Biohydrogen production, Lignocellulosic biomass

URI

https://hdl.handle.net/11511/105335

Collections

Graduate School of Natural and Applied Sciences, Thesis