• Transactions of the Korean hydrogen and new energy society
• /
• v.24 no.2
• /
• pp.99-106
• /
• 2013

The variations of performance and metabolites at an early stage were investigated for the successful start-up technology in continuous fermentative hydrogen production. Unsuccessful start-up was observed when the operation mode was changed from batch to continuous mode after the yield was reached to 0.5 mol $H_2$/mol $hexose_{added}$ by batch mode. $H_2$ production continued till 12 hours accompanied by butyrate production, but did not last with propionate production increase. It was suspected that the failure was due to the regrowth of propionic acid bacteria during batch mode which were inhibited by heat-shock but not completely killed. Thus, successful start-up was tried by early switchover from batch to continuous operation; continuous operation was started after the $H_2$ yield was reached to 0.2 mol $H_2$/mol $hexose_{added}$ by batch mode. Although $H_2$ production rate decreased at an early stage, stable $H_2$ yield of 0.8 mol $H_2$/mol $hexose_{added}$ was achieved after 10 days by lowering down propionate production. And it was also concluded that the reason for $H_2$ production decrease at an early stage was due to alcohol production by self detoxification mechanism against VFAs accumulation.

• Microbiology and Biotechnology Letters
• /
• v.27 no.1
• /
• pp.46-53
• /
• 1999

The purpose of this study was to optimize the conditions of continuous mixed culture of C.butyricum and R. spaeroides K-7, which were able to produce hydrogen using biomass-dreived substrate. To investigate the possibility of continuous culture, semi-continuous culture was carried out for 20 days. In semi-continuous culture using the reactor system, the replacement rate of fresh medium was 30% of total medium volume for the highest hydrogen evolution. In continuous culture, the optimum dilution rate was determined to be 0.05$h^{-1}$. The continuous culture produced 3.1 times as compared with the hydrogen on batch culture. On the other hand, the continuous mixed culture produced 1.3~2.1 times as much as hydrogen of the continuous monoculture of C. butyricum. When 10g of glucose in the media (1l) was supplied as a carbon source on continuous culture, mixed culture of C. butyricum and R. sphaeroides K-7 increased hydrogen evolution rate. Because considerable amount of glutamate was contained in waste water of glutamate fermentation, utilization of glutamate was examined in mixed culture. As a result of examination, production of hydorgen was slightly inhibited by high concentration of glutamate, more than 20mM, on continuous monoculture of R. sphaeroides K-7. On the other hand, both on continuous monoculture of C. butyricum and on mixed culture of C. butyricum and R. sphaeroides K-7, production of hydrogen was not inhibited by high concentration of glutamate such as 100mM. Hence this suggests that high concentration of waste water can be used as good substrate for hydrogen production on monoculture of C. butyricum and mixed culture of C. butyricum and R. sphaeroides K-7.

• Microbiology and Biotechnology Letters
• /
• v.20 no.3
• /
• pp.329-334
• /
• 1992

For the photoproduction of molecular hydrogen by photosynthetic bacteria in outdoor conditions, we constructed automatically controlled semi-continuous culture system. When the amount of hydrogen gas produced can be measured by a gas meter with a pulse generator, the same amount of substrate consumed for hydrogen production could be supplied by micro pump related with timers. Using the apparatus, we examined hydrogen production with immobilized cells of Rhodopseudomonas sPhaeroides B6 in outdoor conditions. In spite of severe fluctuation of weather and illumination, the culture was maintained under good control with regard to hydrogen productivity. It was possible to automate the semi-continuous outdoor culture of photosynthetic bacteria for hydrogen production.

• Environmental Engineering Research
• /
• v.20 no.4
• /
• pp.370-376
• /
• 2015

This study investigated the effects of various arsenite concentrations on bio-hydrogen production from molasses using a sequence batch reactor (SBR) operated in a series of three batch cycles. In the first batch cycle, hydrogen production was stimulated at arsenite concentrations lower than 2.0 mg/L, while inhibition occurred at arsenite concentration higher than 2.0 mg/L compared to the control. Hydrogen production decreased substantially during the second batch cycle, while no hydrogen was produced during the third batch cycle at all tested concentrations. The toxic density increased with respect to the increase in arsenite concentrations (6.0 > 1.6 > 1.0 > 0.5 mg/L) and operation cycles (third cycle > second cycle > first cycle). The presence of microorganisms such as Clostridium sp. MSTE9, Uncultured Dysgonomonas sp. clone MEC-4, Pseudomonas parafulva FS04, and Uncultured bacterium clone 584CL3e9 resulted in active stimulation of hydrogen production, however, it was unlikely that Enterobacter sp. sed221 was not related to hydrogen production. The tolerance of arsenite in hydrogen producing microorganisms decreased with the increase in induction time, which resulted in severing the inhibition of continuous hydrogen production.

• Microbiology and Biotechnology Letters
• /
• v.13 no.3
• /
• pp.303-309
• /
• 1985

Continuous production of hydrogen by Ca alginate-immobilized photosynthetic bacteria was studied in a packed-bed bioreactor. The dilution rate and input concentration of carbonaces substrate were selected as operating parameters. To choose the strain for immobilization, hydrogen productivities of Rhodopseudomonas caposulata 10006 and Rhodospirillum rubrum KS-301 were compared through preliminary batch cultures of their free cells: the former was found to show better hydrogen productivity in spite of its lower specific growth rate. For the continuous production of hydrogen by immobilized R capsulata, the optimum dilution rate was about 0.84 h$^{-1}$ . The Immobilized tells gave better hydrogen yield and conversion efficiency than free ones. And a kinetic parameter K'$_{m}$ was determined for the packed-bed bioreactor, being practically constant for a specific range of dilution rates.s.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.06a
• /
• pp.478-481
• /
• 2006

Energy is vital to global prosperity, yet dependence on fossil fuels as our primary energy source contributes to global climate change environmental degradation, and health problems. Hydrogen $(H_2)$ offers tremendous potential as a clean renewable energy currency. Hydrogen has the highest gravimetric energy density of any known fuel and is compatible with electrochemical and combustion processes for energy conversion without producing carbon-based emission that contribute to environmental pollution and climate change. Numerous methodologies have been developed for effective hydrogen production. Among them, the biological hydrogen production has gained attention, because hydrogen can be produced by cellular metabolismunder the presence of water and sunlight. The green alga Chlamydomonas reinhardtii is capable of sustained $H_2$ photoproduction when grown under sulfur deprived condition. Under sulfur deprived conditions, PSII and photosynthetic $O_2$ evolution are inactivated, resulting in shift from aerobic to anaerobic condition in the culture. After anaerobiosis, sulfur deprived algal cells induce a reversible hydrogenase and start to evolve $H_2$ gas in the light. According to above principle, we investigated the effect of induction parameters such as cell age, cell density. light intensity, and sulfate concentration under sulfur deprived condition We also developed continuous hydrogen production system by sulfate re-addition under sulfur deprived condition.

• Journal of Wetlands Research
• /
• v.9 no.1
• /
• pp.123-131
• /
• 2007

Effect of nitrogen-load condition on hydrogen ($H_2$) production and bacterial community in a continuous anaerobic hydrogen fermentation were investigated. The slight $H_2$ production on extremely low nitrogen-load condition (C/N ratio: 180) at the start-up period. The highest $H_2$ production was obtained when the C/N ratio was 36, the $H_2$ production yield ($mol-H_2/mol-glucose$) reached to 1.7, and it was indicated that Clostridium pasteurianum mainly contributed to the $H_2$ production. The $H_2$ production was decreased on both the lower (C/N: 72) and higher (C/N: 18) nitrogen-load conditions. The excess nitrogen-load was not always suitable for the hydrogen production. The fluctuation of $H_2$ production seemed to be caused by a change in the bacterial community according to the nitrogen-load condition, while a recovery of $H_2$ productivity was possible by a control of nitrogen-load condition through the bacterial community change. When the nitrogen-load condition was not suitable for hydrogen production, the lactic acid concentration was increased and also lactic acid bacteria were definitely detected, which suggested that the competition between hydrogen fermentator and lactic acid producer was occurred. These results demonstrated that the nitrogen-load condition affect on the $H_2$ productivity through the change of bacterial community in anaerobic hydrogen fermentation.

• Microbiology and Biotechnology Letters
• /
• v.17 no.6
• /
• pp.629-633
• /
• 1989

In the continuous reactor, the hydrogen production rate and residual glucose concentration were increased with increase of input glucose concentration, dilution rate, and recycle rate. The maximum production rate was 91 mL/Lㆍh at dilution rate 0.4/h, input glucose concentration 5.4g/L, and recycle rate 70/h in this experimental range.

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.11a
• /
• pp.299-306
• /
• 2005

Anaerobic fermentation of food waste (FW) and waste activated sludge (WAS) for hydrogen production was performed in CSTR (Continuous Stirred tank reactor) under various HRTs and volumetric mixing ratio (V/V) of two substrates, FW and WAS. The specific hydrogen production potential of FW was higher than that of WAS. However, pH drop in the CSTR for hydrogen production from FW was higher than that from WAS. The maintenance of desired pH during fermentative hydrogen production is regarded as the most important operation parameter for the stable hydrogen production. Therefore, when the potential of hydrogen production from FW and better buffer capacity of WAS, the proper mixture of FW and WAS for fermentative hydrogen production were considered as a useful complementary substrate. The maximum yield of specific hydrogen production, 140 mL/g VSS, was found at HRT of 2 day and the volumetric mixing ratio of 20:80 (WAS : FW). The spatial distribution of hydrogen producing bacteria was observed in anaerobic fermentative reactor using fluorescent in situ hybridization (FISH) method.

• KSBB Journal
• /
• v.20 no.5 s.94
• /
• pp.350-354
• /
• 2005

In order to maximize hydrogen production by Enterobacter cloacae YJ-1, anaerobic hydrogen producing bacteria, the medium composition was optimized. Glucose was better than other carbon sources in hydrogen production and its production was 975.4 mL/L at $2\%$ (w/v) for 48 h. Organic nitrogen sources were more effective than inorganic nitrogen sources and also yeast extract among organic nitrogens was the most effective in hydrogen production. Among metal ions, $Na_2MoO_4$ was most effective, and its production was 1753.3mL/L at $0.04\%$ (w/v). Addition of amino acid was very effective with compare to another components of medium, and cystein was most effective among them. Under the optimum medium obtained in batch culture, semi-batch culture in order to produce continuous hydrogen was run. The highest hydrogen production was earned at $3\%$(w/v) of glucose and the amount was 2215.4 mL/L.