Significance of carbon to nitrogen ratio on the long-term stability of continuous photofermentative hydrogen production

Androga, Dominic Deo; Özgür, Ebru; Eroğlu, İnci; Gündüz, Ufuk; Yücel, Meral

doi:10.1016/j.ijhydene.2011.09.043

Cited by 50 publications

(18 citation statements)

References 34 publications

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“…In all of the runs, light conversion efficiencies were calculated to be in the range of 0.35-0.41 %; these are on par with the values reported previously with same bacteria in indoor conditions [21,22]. There are a few published studies which compare hup -mutant and wild-type R. capsulatus cells for their growth and hydrogen productions on various substrates.…”

Section: Resultssupporting

confidence: 66%

“…For continuous operation, 400 mL of media from photobioreactor (10 % of culture volume of 4-L photobioreactor) was replaced by fresh media daily corresponding to a dilution rate of 0.1, which was reported to be the optimum value to stabilize biomass and maximize hydrogen productivity in hydrogen production experiments using R. capsulatus [8,18]. Daily feeding to the photobioreactors was started after 2nd day.…”

Section: Photobioreactors and Operating Conditionsmentioning

confidence: 99%

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Hydrogen production by hup− mutant and wild-type strains of Rhodobacter capsulatus from dark fermentation effluent of sugar beet thick juice in batch and continuous photobioreactors

Uyar

Gürgan

Özgür

et al. 2015

Bioprocess Biosyst Eng

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Photofermentative production of hydrogen is a promising and sustainable process; however, it should be coupled to dark fermentation to become cost effective. In order to integrate dark fermentation and photofermentation, the suitability of dark fermenter effluents for the photofermentative hydrogen production must be demonstrated. In this study, thermophilic dark fermenter effluent (DFE) of sugar beet thick juice was used as a substrate in photofermentation process to compare wild-type and uptake hydrogenase-deficient (hup (-)) mutant strains of Rhodobacter capsulatus by means of hydrogen production and biomass growth. The tests were conducted in small-scale (50 mL) batch and large-scale (4 L) continuous photobioreactors in indoor conditions under continuous illumination. In small scale batch conditions, maximum cell concentrations were 0.92 gdcw/L c and 1.50 gdcw/L c, hydrogen yields were 34 % and 31 %, hydrogen productivities were 0.49 mmol/(L c·h) and 0.26 mmol/(Lc·h), for hup (-) and wild-type cells, respectively. In large-scale continuous conditions, maximum cell concentrations were 1.44 gdcw/L c and 1.87 gdcw/L c, hydrogen yields were 48 and 46 %, and hydrogen productivities were 1.01 mmol/(L c·h) and 1.05 mmol/(L c·h), for hup (-) and wild-type cells, respectively. Our results showed that Rhodobacter capsulatus hup (-) cells reached to a lower maximum cell concentration but their hydrogen yield and productivity were in the same range or superior compared to the wild-type cells in both batch and continuous operating modes. The maximum biomass concentration, yield and productivity of hydrogen were higher in continuous mode compared to the batch mode with both bacterial strains.

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Section: Resultssupporting

confidence: 66%

Section: Photobioreactors and Operating Conditionsmentioning

confidence: 99%

Hydrogen production by hup− mutant and wild-type strains of Rhodobacter capsulatus from dark fermentation effluent of sugar beet thick juice in batch and continuous photobioreactors

Uyar

Gürgan

Özgür

et al. 2015

Bioprocess Biosyst Eng

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“…S/X ratio (based on VS) could be an indicator of C/N ratio. Effect of C/N ratio is proven to be important for growth of microorganisms [36][37][38]. High initial VS impairs mass transfer between microorganisms and substrate while the very low VS restricts metabolisms in other ways.…”

Section: Introductionmentioning

confidence: 99%

Enhanced mesophilic bio-hydrogen production of raw rice straw and activated sewage sludge by co-digestion

Alemahdi

Man

Rahman

et al. 2015

International Journal of Hydrogen Energy

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Abstract:In this study, batch biohydrogen production by co-digestion of raw rice straw and activated sewage sludge was investigated with different inoculum heat treatment, pH, S/X ratio (based on VS) and substrate sizes under mesophilic condition. In order to achieve a high bio-hydrogen yield and methanogens activity inhibition, heat treatment of inoculum was optimized at different exposure times (30, 45 & 60 min) and temperature ranges (80, 90 and 100 °C) prior to dark fermentation process. Collected data was analysed using response surface methodology (RSM).The heat treatment of inoculum at 100 °C for 60 minutes produced the highest bio-hydrogen yield of 14.22 NmL H2/g VS at concentration of 70.97 % and Production of 0.073 NmLCH4/gVS at 0.17% concentration in total produced biogas. The raw rice straw was also co-digested with heat-treated inoculum at different ratios of volatile solids (2:1, 4:1 and 6:1) and initial pH (4, 4.75 and 5.5) as numerical variables and 4 categories of substrate size ( (250-500 µm], (500 µm-2mm], (2-20mm), [20-30mm]) . The highest bio-hydrogen yield of 14.70 NmL/g VS was recognized at the optimum initial pH of 5.01 and S/X ratio of 4.54:1 using 2-20 mm rice straw.

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“…Suspended systems are prone to washouts and product inhibition, which could be overcome by cell recycle. Immobilized systems offer the advantages of cell longevity and have been shown to produce hydrogen at higher rates and yields [74,75]. Studies using different HRT values indicate that longer HRT is more suitable for photofermentation as the PNSB utilized the fed organic acids slowly [34,[76][77][78]).…”

Section: Mode Of Operation: Batch Continuous and Fed-batch Systemsmentioning

confidence: 99%

“…Likewise, different materials have been used to immobilize the photosynthetic cells. Agar, alginate, carrageenan, cellulose and its derivatives, collagen, gelatin, epoxy resin, photo cross-linkable resins, polyacrylamide, polyester, polystyrene, polyurethane and porous glass are the most commonly used materials [74,82,[120][121][122]. Gel entrapment was stated to be the best means of immobilizing bacterial cells [121,123].…”

Section: Immobilization Studiesmentioning

confidence: 99%

Photofermentative Hydrogen Production in Outdoor Conditions

Androga¹,

Özgür²,

Eroğlu³

et al. 2012

Hydrogen Energy - Challenges and Perspectives

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Significance of carbon to nitrogen ratio on the long-term stability of continuous photofermentative hydrogen production

Cited by 50 publications

References 34 publications

Hydrogen production by hup− mutant and wild-type strains of Rhodobacter capsulatus from dark fermentation effluent of sugar beet thick juice in batch and continuous photobioreactors

Hydrogen production by hup− mutant and wild-type strains of Rhodobacter capsulatus from dark fermentation effluent of sugar beet thick juice in batch and continuous photobioreactors

Enhanced mesophilic bio-hydrogen production of raw rice straw and activated sewage sludge by co-digestion

Photofermentative Hydrogen Production in Outdoor Conditions

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