• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.542-549
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• 2015

The bioelectrochemical anaerobic digestion for sewage sludge was attempted at different applied voltages ranged from 0.2 V to 0.4 V. At 0.3 V of the applied voltage, pH and VFAs were at 7.32 and 760 mg COD/L, respectively, which were quite stable. The methane production rate was $1.32L\;CH_4/L.d$, and the methane content in biogas was 73.8%, indicating that the performance of the bioelectrochemical anaerobic digestion could be considerably improved by applying a low voltage. At 0.4 V of the applied voltage, however, the contents of the minor VFA components including formic acid and propionic acid were increased. The methane production rate was reduced to $1.24L\;CH_4/L.d$ and the biogas methane content was also reduced to 72.4%. At 0.2 V of the applied voltage, the pH was decreased to 6.3, and VFAs was accumulated to 5,684 mg COD/L. The contents of propionic acid and butyric acid in the VFAs were considerably increased, The performances in terms of the methane production rate and the biogas methane content were deteriorated. The poor performance of the bioelectrochemical reactor at 0.2 V of the applied voltage was ascribed to the thermodynamic potential lack for the driving of the carbon dioxide reduction into methane at cathode.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.2
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• pp.127-131
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• 1993

A newly developed waste-water treatment system for small scale piggery wastes through a demonstration trial at a farm. The results are summarized as follows. 1. The amount of piggery wastes produced was 10.2kg/head/day, which consisted of 2.8kg solid wastes and $7.41{\ell}$ fluid wastes. 2. The unit BOD discharge from piggery wastes was 207g/head/day, among which 81 percent was originated from solid waste and 19 percent from fluid waste. 3. After the treatment of the waste-water through the system, BOD, total N and total P were lowered by 99, 78, 74 percent, respectively : the BOD, total N and total P in the final effluent were $52mg/{\ell}$, $213mg/{\ell}$ and $28mg/{\ell}$, respectively. 4. The results of the trials suggested that the system could be recommended for the practical use at the farms.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.417-427
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• 2000

The substrate metabolism and bacterial population in an anaerobic digestion with the submerged separation membrane were investigated by using a laboratory-scale reactor at the hydraulic retention time(HRT) 1.0 and 0.5 day. The removal efficiencies of carbohydrate at the HRT 1.0 and 0.5 day were 99.8~99.9% and 98.0~99.6%, respectively. After the 58 days, the mixed liquor volatile suspended solids(MLVSS) concentration at the HRT 1.0 and 0.5 day were approximately 6,050 and 7,750 mg/L, respectively. According to the measurement by the most probable number(MPN) method, the numbers of acidogenic bacteria, $H_2$-utilizing and acetate-utilizing methc.nogenic bacteria were found to be $10^9$, $10^7{\sim}10^8$ and $10^6{\sim}10^8MPN/mL$, respectively. The composition of $CH_4$ in the produced gas was 46~50%. It is suggested that sulfate-reducing bacteria $10^7{\sim}10^8MPN/mL$ play an important role in producing $H_2$ and acetate in sulfate-depleted environment.

• Journal of Environmental Science International
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• v.23 no.6
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• pp.1061-1066
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• 2014

This study has cross checked the change of internal sludge-recycle in Anaerobic-Digestion, and researched about not only the improvement of Bio-gas production from the digested sludge but also the efficient method of sludge minimization. Ultimate object of the study is to reduce the amount of sludge by the improved efficiency of contact with the organic-matter and the microbes in Anaerobic-Digestion. The sludge-recycle fluidized sludge layer and raised the activity of the sludge, the optimal sludge-recycle ratio, VS and COD removal ratio were 1,000%, 28.2% and 27.7%, respectively. Through these results of this study, it may be of use to treat waste sludge by the sludge-recycle ratio in terms of minimization and circulation of resources.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.4
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• pp.55-60
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• 2001

This study was performed to investigate production characterisitic of methane gas in anaerobic digestion reactor according to input type of food waste. In the production rates of $CH_4$ gas per g $VS_{added}$, reactor R2, R3, R4, R5, and R6 in which sewage sludge and food waste were combined with mixing ratio of 1:0.1, 1:0.3, 1:0.5, 1:1, and 1:2 showed 85mL, 62mL, 67mL, 72mL, and 73mL $CH_4/g$ $VS_{added}$ which were much more than sewage sludge digestion alone. Methane content according to crushing size of food waste respectively showed 51.1%(raw food), 53.1%(2~4mm), and 50.6%(<2mm), In case of methane production according to washing of food waste, R12(7~8 times washing) showed the highest methane production.

• Journal of the Korea Organic Resources Recycling Association
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• v.7 no.2
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• pp.47-55
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• 1999

Recently, the treatment of that wastes according to increase of food waste has been a great problem of modern society for long time. This study was aimed to evaluate possibility for food waste and sewage sludge mixture treatment using pilot scale two-phase anaerobic digester. Pilot scale two-phase anaerobic digestion system was performanced at 1 : 9 mixture ratio of food waste and sewage sludge infield. The detention time of digester was 20days. The average COD and VS removal efficiencies in organic loading rate $3.03kg\;TCOD/m^3-day$ were 57.7 and 47.7%, and the gas production rate and methane content were $0.4m^3/kg$ VS-day and 65.3%, respectively. TS, VS and VS/TS(%) of mixing tank were 4.44%, 2.59% and 58.34%, respectively and TS. VS and VS/TS(%) of digester in steady state were 3.32%, 1.39% and 41.90%, respectively, Through this study. it was possible to accomplish effective mixture treatment of the sewage sludge and food waste.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.1
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• pp.171-177
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• 2007

In order to investigate the effect of the methanogenic bacteria in bacteria in leachate on the degradability of landfill waste, this study has created 4 cylinder-shape PVC lysimeters (Diameter: 30cm, Height: 200cm, Volume: 140L) and for the biological treatment and recirculation of the leachate, two anaerobic batch reactors (Diameter: 20cm, Height: 30cm) were created. To simulate a conventional landfill, no recycling was done in L1. In L2, 1,068ml of leachate (twice of rainfall amount) was recycled. In L3 and L4, the leachate was anaerobically digested in a dark room (with $35{\pm}1^{\circ}C$) for a week and them recycled by 1,064ml and 2,128ml, respectively, with recycled water only. In terms of cumulative $CH_4$ production, however, L3 and L4 were much higher (three times) than L1 and L2. Between L3 and L4, the latter was 1.23 times higher than the former in terms of cumulative CH4 production. In other words, the more the methanogenic bacteria-activated leachate is recycled, the more active the degradation due to active methane fermentation by the recyled methanogenic bacteria. And methane recovery is different according to the amount of recycled the methanogenic bacteria in leachate.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.246.1-246.1
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• 2010

본 연구는 바이오가스의 에너지효율성을 높이기 위한 연구로서 바이오가스 정제공정과 초저온액화공정을 통하여 액화바이오메탄을 생산하는 바이오가스 고질화기술개발 연구이다. 바이오가스 정제공정은 탈황, 제습, 흡착, 압축, $CO_2/CH_4$ 분리공정으로 구성하고, 초저온액화공정은 열교환기, $CO_2$ 제거설비, 질소냉매 공급공정으로 구성하여 혐기성소화조에서 발생하는 바이오가스($CH_4$ 농도: 60~65%, $H_2S$: 1,500~2,500ppm)를 $200Nm^3/hr$의 유량으로 인입시켜 액화바이오메탄을 생산하였다. 연구결과, 탈황공정에서는 가성소다 세정법을 이용하여 1,500~2,500ppm으로 인입되는 $H_2S$를 100ppm 이하로 제거한 후, 흡착법을 이용하여 $H_2S$를 완전히 제거하였다. 바이오가스에 포화된 수분은 냉각제습과 흡착제습공정을 통해 Dew point $-70{\sim}-90^{\circ}C$까지 제거하여 안정적으로 $CO_2/CH_4$ 분리공정에 인입시켰다. $CO_2/CH_4$ 분리공정은 흡착방식을 적용하여 $CH_4$ 순도가 95% 이상인 바이오메탄을 생산하였으며, 이때 메탄 회수율은 약 87%이였다. $CO_2$가 분리된 바이오메탄은 초저온액화공정을 이용하여 액화바이오메탄으로 전환시켰다. 이때 초저온액화공정은 Reverse Brayton cycle로 구성하였으며, 냉매로는 질소를 사용하였다. 액화바이오메탄의 생산은 바이오메탄을 등엔트로피과정인 단열팽창을 통하여 $-155{\sim}-159^{\circ}C$의 초저온으로 냉각되는 질소냉매와 열교환기에서 열교환시켜 이루어졌으며 그 생산량은 $3.46m^3$/day(1bar, $-161^{\circ}C$)이었다.

• Journal of Korean Society on Water Environment
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• v.32 no.3
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• pp.297-302
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• 2016

Microbial electrochemical technology (MET) has recently been studied to improve the efficiency of a traditional anaerobic digestion (AD). The purpose of this study was to investigate the impact of MET in the system when MET was combined with traditional AD (i.e., AD-MET). Electrodes used in the MET were Cu coated graphite electrodes. They were supplied with a voltage of 0.3 V. AD started to generate methane in 80 days. But AD-MET started to generate methane from the initial operation after the system started. It was observed that AD-MET reached steady state faster and produced higher methane yield than AD. During the steady state, the average daily methane productions in AD and AD-MET were 2.3L/d and 4.9L/d, respectively. Methane yields were 0.07-CH₄/g‧CODre in AD and 0.25L-CH₄/g‧CODre in AD-MET. In AD-MET, the production rates of total volatile fatty acids (TVFAs) and soluble chemical oxygen demand (SCOD) were 0.12 mg TVFAs/mg VS‧d and 0.35 mg SCOD/mg VS‧d, respectively. They were significantly (p < 0.05) higher than those in AD. However, the concentrations of residual TVFAs in both systems were not significantly (p > 0.05) different from each other, confirming that methane conversion in AD-MET was greater than that in AD.

• Journal of Wetlands Research
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• v.22 no.4
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• pp.239-244
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• 2020

Prior to utilization of energy and power generation, the biogas from anaerobic digestion of sewage treatment plant(46,000㎡/d) should be purified particularly hydrogen sulfide among the various kinds of impurities. This study has focused on the methane decreasing rate and the removal of both hydrogen sulfide and carbon dioxide. In the case of partial circulation, 59.7% of methane gas was decreased to 57.4% in spite of oxidation process with micro-bubble. Carbon dioxide was removed from 38% to 32% and 76.1% of hydrogen sulfide was removed where 1,400ppm was introduced to the DIWS system, which indicated that DIWS system can be of use for the hydrogen sulfide removal of biogas from sewage treatment plant.