• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.3
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• pp.97-105
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• 2007

This study was conducted to compare the performances of acidogenic fermentation and hydrogen fermentation using bench-scale leaching-bed reactors for organic solid waste. Acidogenic fermenters were operated with dilution rates (D) of 2.0, 3.0 and $4.0d^{-1}$ after employing anaerobic sludge and hydrogen fermenters were operated with D of 2.0, 4.0 and $6.0d^{-1}$ after employing heat-treated anaerobic sludge. The highest chemical oxygen demand (COD) conversion efficiency (56.2%) was obtained in acidogenic fermentation with D of $3.0d^{-1}$. Only volatile fatty acid (VFA) was produced as a metabolite. On the other hand, hydrogen fermentation did not show higher COD conversion efficiency (49.3%) than acidogenic fermentation, but it produced hydrogen gas (5.1% of total COD) which was a clean and environmentally friendly fuel with a high energy yield. Therefore, either acidogenic fermentation or hydrogen fermentation could be applied to organic solid waste depending on the purpose of treatment, which could maximize the economics of anaerobic treatment.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.2
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• pp.49-54
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• 2011

This study was conducted to evaluate the performance of methane fermentation from effluent of hydrogen fermentation reactor in anaerobic baffled reactor (ABR) and anaerobic sequencing batch reactor (ASBR). Two reactors were operated at organic loading rate of $1.0kg\;COD/m^3{\cdot}d$ and hydraulic retention time (HRT) of 20 day. Methane production rates of ABR and ASBR for start-up periods were 0.04 L/L/d and 0.19 L/L/d, respectively, whereas maximum methane production rates of ABR and ASBR were 0.25 L/L/d and 0.31 L/L/d, respectively. Removal rates of chemical oxygen demand (COD) in ABR and ASBR for start-up periods were 89% and 92%, respectively. After startup periods, removal rates of COD and volatile solids (VS) in ABR and ASBR were maintained over 90%. The specific methanogenic activity (SMA) increased as microorganism acclimated to the substrate.

• Journal of Environmental Health Sciences
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• v.26 no.2
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• pp.1-5
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• 2000

연속형 혐기성처리 반응조에서 배양된 수소발생 슬러지를 이용하여 증온 조건에서 회분식 혐기성 처리방법으로 유기성 폐수로부터 전환되는 수소가스 및 대사산물들에 대한 연구를 수행하였다. 수소발생에 대한 기질로는 sucrose를 이용하였다. 처리과정에서 발생된 누적수소가스, 휘발성지방산(VFAs) 및 solvents는 Gompertz equation을 이용한 비선형회귀분석을 통하여 계산하였다. 처리과정 중 수소가스는 반응초기에 발생하였고, 발생된 가스내 수소가스가 차지하는 비율은 약 20%이었다. 반응 전과정에서 메탄가스는 발생하지 않았다. 비수소가스발생율은 sucrose 농도가 40 g/l일 때 0.956 ml/g VSs/h이었으며, sucrose 농도가 300g/l의 경우는 0.011 ml/g VSS/h이었다. 수소가 발생하는 기간 동안 VFAs의 생성은 acetate, butyrate의 순으로 높게 생성되었으나, propionate로의 전환은 발견되지 않았다. solvents의 경우 butanol이 가장 높게 발생하였다.

• KSBB Journal
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• v.20 no.6
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• pp.443-446
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• 2005

Hydrogen fermentation from food waste was attempted at different hydraulic retention time(HRT, 18-42 h). A continuous reactor fed with ground, alkali-treated and diluted food waste(average VS 4.4%) exhibited stable hydrogen production during 126 days. Hydrogen production depended on HRT, resulting in the maximum values of 25.8 mL $H_2/g\;VS_{added}$, 0.36 mol $H_2/mol\;hexose_{added}$ and 0.91 L $H_2/L/d$ at HRT 30 h. n-Butyrate and isopropanol production increased with hydrogen production increased, while acetate production decreased. The fermentation efficiency ranged from 53.3 to 65.7%, which implied that hydrogen fermentation would substitute conventional acidogenesis of food waste.

• Journal of Hydrogen and New Energy
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• v.18 no.3
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• pp.223-229
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• 2007

여과막 생물반응기를 이용하여 $60^{\circ}C$에서 혐기 세균 복합체가 포도당으로부터 수소를 생산할 수 있는 최적조건을 연구하였다. 여과막 생물반응기는 연속교반 탱크반응기와 외부에 장착된 PVDF (polyvinylidene fluoride) 중공사막 여과장치로 구성되었다. 접종슬러지는 하수처리장 소화 슬러지조에서 얻었고, 포자형성 수소생산 미생물을 얻기 위해 $90^{\circ}C$에서 20분 간 열처리하였다. 16S rRNA PCR-DGGE(polymer chain reaction-denaturing gradient gel electrophoresis) 분석을 통해 열처리 전후의 미생물상 변화를 조사하였다. 열처리 후 DGGE 밴드의 수는 감소하였고, 주요 밴드는 Clostridium perfringens와 유사한 염기서열을 나타내었다. 운전 기간 동안 바이오가스 내 수소함량은 60%(v/v)를 유지하였고, 메탄은 검출되지 않았다. 연속교반 탱크반응기를 여과막 없이 수력학적 체류 4시간에서 운전하였을 때 공급된 포도당의 95.0%가 제거되었고, 이때 균체농도 및 수소생산속도는 각각 1.35 g cell/L 및 7.4 L $H_2$/L/day이었다. 동일한 체류시간에서 PVDF중공사막 여과장치를 장착하여 연속교반 탱크반응기를 운전하였을 때, 균체농도는 1.62 g cel/L로 증가하였고 높은 포도당 제거율(99.5%) 및 수소생산속도(8.8 L $H_2$/L/day)가 관찰되었다. 40 nm 및 100 nm의 공극크기를 가진 여과막은 균체농도 및 수소생산 측면에서 유사한 성능을 나타내었다. 여과막 생물반응기는 여과막의 반복적인 세척을 통해 30일 이상 안정적으로 운전될 수 있었다.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.4
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• pp.105-113
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• 2003

Successful operation of a reactor can be accomplished when it is operated at proper D depending on the state of degradation. Operation at high D leads to the washout of biomass in the reactor while operation at low D leads to product inhibition due to the accumulation of excess VFA. These appear to limit the production of hydrogen to reach a higher level. Operation by D control was performed to improve the efficiency of hydrogen fermentation of food waste. Although simple organic matters were rapidly degraded in the early stage (day 1-2), proper VFA concentration and pH values were kept in the reactor at D of $4.5d^{-1}$, which was previously reported to be optimum initial D. High butyrate/acetate (B/A) ratios over 3.2 were obtained. Without D control, the reduction of simple organic matters after day 2 caused the decrease of VFA production and the increase of pH. Hydrogen production also decreased, as microbial proliferation was less than microbial loss by washout. However, the reactor performance was dramatically improved at D control from 4.5 to $2.3d^{-1}$. It showed the highest B/A ratios over 2.0 among the reactors on day 4-7. The second hydrogen peak appeared on day 4, resulting in the highest fermentation efficiency (70.8%) among the reactors. It was caused by the enhanced degradation of slowly degradable matters. The COD removed was converted to hydrogen (19.3%), VFA (36.5%), and ethanol (15.0%). Therefore, the strategy using D control, depending on the state of degradation, was effective in improving the efficiency of hydrogen fermentation.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.1
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• pp.102-108
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• 2011

Characteristics of hydrogen production from various food wastes in anaerobic batch reactors were evaluated to assess the energy potential of organic wastes. Organic wastes which were used in this study were scallion as vegetable, apple as fruit, rice as grain and pork as meat. Ultimate hydrogen yield of scallion, apple, rice and pork were 0.46, 0.47, 0.62 and $0.05mol\;H_2/mol\;hexose$, respectively. On the other hand, hydrogen production rates of scallion, apple, rice and pork were 0.013, 0.021, 0.014 and $0.005mol\;H_2/mol\;hexose/h$, respectively. These results indicated that anaerobic hydrogen fermentation from food waste except for meat was effective in removing organic material as well as producing renewable energy. Volatile fatty acids increased as hydraulic retention time was increased. In the hydrogen fermentation, acidification degree of rice was measured as the highest rate of 75.8% whereas pork was found as the lowest rate of 35.2%.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.3
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• pp.87-95
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• 2003

Although extensive studies were conduced on hydrogen fermentation of organic wastewaters, little is known about biohydrogen production from organic solid wastes. The leaching-bed reactor treating food waste by heat-shocked anaerobic sludge was, therefore, operated at D of 2.1, 3.6, 4.5 and $5.5d^{-1}$ to find optimal D for hydrogen production. Successful operation of a reactor can be accomplished when it is operated at proper dilution rate (D). Operation at high D leads to the washout of biomass in the reactor while operation at low D leads to product inhibition due to the accumulation of excess VFA. These appear to limit the production of hydrogen to reach a higher level. All the reactors showed that, on day 1-3, hydrogen production was dominant and VFA concentration was higher than ethanol. Butyrate and acetate were major components of VFAs over the whole operation, though lactate was very high on day 1-2. Compared with other D values, D of $4.5d^{-1}$, resulted in higher butyrate/acetae (B/A) ratios during the fermentation. The trend of B/A ratios was similar to the hydrogen production, suggesting that butyrate formation favored hydrogen production. Ethanol increased significantly from day 4 when hydrogen Production stopped. It indicated that heat-shocked sludge was able to induce a metabolic flow from hydrogen-and acid-producing pathway to solvent-producing pathway. Operation at D of $4.5d^{-1}$ led to higher fermentation efficiency (58%) than those (51.5, 55.3 and 53.7%) at 2.1, 3.6 and $5.5d^{-1}$. The COD removed was convened to hydrogen (10.1%), VFA (30.9%), and ethanol (17.0%).

• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.307-311
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• 2014

This study investigated the effects of polyurethane foam on continuous hydrogen production from mixed wastes. Molasses was co-fermented with non-pretreated sewage sludge in a sequencing batch reactor. The results indicated that the addition of polyurethane foams as a microbial carrier in the reactor mitigated biomass loss at HRT 12 h, while most of the biomass was washed out during the operation period with no carrier. There was a stable hydrogen production rate of $0.4L-H_2/l/d$ in the carrier-sequencing batch reactor. Suspended biomass in the carrier-reactor indicated it possessed the highest specific hydrogen production rate ($241{\pm}4ml-H_2/g\;VSS/d$) when compared to that of biomass on the surface ($133{\pm}10ml-H_2/g\;VSS/d$) or inner carrier ($95{\pm}14ml-H_2/g\;VSS/d$).

• Journal of Hydrogen and New Energy
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• v.19 no.5
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• pp.410-416
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• 2008

합성 및 두부 제조 폐수로부터 혐기 세균 복합체를 이용하여 수소를 생산하였다. 수소생산 혐기 세균 복합체는 하수처리장 농축 소화조에서 발생하는 슬러지를 $90^{\circ}C$에서 20분간 열처리하여 얻었다. 혐기 세균 복합체는 $37^{\circ}C$ 회분식 운전조건에서 1% (w/v) 포도당 함유 PYG (peptone-yeast extract-glucose) 배지로부터 1.15 L-$H_2$/g-균체건조량의 수소를 생산할 수 있었고, 이때 주요 유기산으로 15 mM acetate와 32 mM butyrate가 생성되었다. 같은 발효조건에서 1.4% 전분과 0.07% 환원당을 포함하는 두부 제조 폐수로부터 1.76 L $H_2$/L-두부제조폐수의 수소를 발생하였다. 이와 같은 결과로 부터 포도당과 두부 제조 폐수로부터 혐기세균 복합체에 의한 수소생산 효율은 각각 1.9과 0.9 mol $H_2$/mol 포도당을 나타내었다. 반연속운전(HRT, 12 시간)시 합성폐수를 이용하여 60일 이상 안정적으로 수소를 생산할 수 있었고, 이 때 혐기 세균 복합체는 1.3-2.0 L $H_2$/L-배양액을 발생하였다. PCR-DGGE(polymer chain reaction-denaturing gradient gel electrophoresis) 분석결과, 반응기 내 세균 복합체의 주요 미생물은 Clostridium 종이었다. 본 연구는 적절한 열처리를 통해 혐기 소화조 슬러지로부터 고활성 수소생산 세균 복합체를 얻을 수 있으며, 이들 세균 복합체를 이용하여 합성 및 두부제조 폐수로부터 효율적인 수소생산이 가능하다는 것을 나타내고 있다.