• Journal of Korean Society of Environmental Engineers
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• v.31 no.5
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• pp.341-345
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• 2009

Continuous dry anaerobic digestion of organic solid wastes (30% TS, Total Solids) comprised of food waste and paper was performed under mesophilic condition. During the operation, hydraulic retention time (HRT) was decreased as follows: 150 d, 100 d, 60 d, and 40 d, which corresponded to the solid loading rate of 2.0, 3.0, 5.0, and 7.5 kg TS/$m^3$/d, respectively. Volumetric biogas production rate ($m^3$/$m^3$/d) increased as HRT decreased, and the highest biogas production rate of 3.49${\pm}$0.31 $m^3$/$m^3$/d was achieved at 40 d of HRT. At this HRT, high volatile solids (VS) reduction of 76% was maintained, and methane production yield of 0.25 $m^3$/kg $TS_{added}$ was achieved, indicating 67.4% conversion of organic solid waste to bioenergy. The highest biogas production yield of 0.52 $m^3$/kg $TS_{added}$ was achieved at 100 d of HRT, but it did not change much with respect to HRT. For the ease feed pumping, some amount of digester sludge was recycled and mixed with fresh feed to decrease the solid content. Recirculation volume of 5Q was found to be the optimal in this experimental condition. Specific methanogenic activity (SMA) of microorganisms at mesophilic-dry condition was 2.66, 1.94, and 1.20 mL $CH_4$/g VS/d using acetate, butyrate, and propionate as a substrate, respectively.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.2
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• pp.118-127
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• 2007

This study investigated the effect of varying TS concentration levels using supernatant of food waste. The experiment was performed at varying TS concentration levels ranging from 5% to 10% by a $35^{\circ}C$-mesophilic digestion reactor, dual digestion system with acid and methane fermenters combined. As a result, removal efficiency and stabilization were observed at TS concentration of 7~8%, But the removal efficiency notably decreased at 8% or higher TS level. At a stabilized phase of the reactor, more than $0.3m^3/kg{\cdot}vs$ gas was produced, with phenomena such as salt accumulation and increase of pH level being unnoticed. These results indicate that the increase of anaerobic digestion of food waste supernatant TS content has an effect on reaction and that it is necessary to control and operate concentration within 8%, given that the effect is stronger at 8% or higher.

• Korean Journal of Environmental Agriculture
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• v.18 no.1
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• pp.54-60
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• 1999

Three different types of lab-scale anaerobic bioreactors, AF and two-stage ASBF-PR and ASBF-SP, were evaluated in treating swine wastewater by operating at $1{\sim}2$ days of hydraulic retention time with increasing organic loading rate upto 6.3 $kg-COD/m^3{\cdot}d$ at $35^{\circ}C$. Seeding the anaerobic bioreactors with waste anaerobic digester sludge from a municipal wastewater treatment plant was effective and a 40-day acclimation period was required for steady-state operation. Three anaerobic bioreactors were effective in treating swine wastewater with COD removal efficiency of $66.4{\sim}84.9$% and biogas production rate of $0.333{\sim}0.796m^3/kg-COD_{removed}{\cdot}d$. Increases of organic loading rate by increasing influent COD concentration and/or decreasing hydraulic retention time caused decreases in COD removal efficiency and increases in biogas production rate. At relatively high organic loading rate employed in this study, the treatment efficiency of AF and ASBF-PR were similar but superior than that of ASBF-SP, indicating that porosity and pore size of the media packed in the bioreactors are more important factors contributing the performance of to bioreactors than specific surface area of the media. TKN in swine wastewater must be removed prior to the anaerobic processes when anaerobic process is considered as a major treatment process since influent TKN concentration of $1,540{\sim}1,870mg/L$ to the bioreactors adversely affect the activity of methanogenic bacteria, resulting in decreases of treatment efficiency and biogas production rate by 50%.

• KSBB Journal
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• v.22 no.2
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• pp.97-101
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• 2007

This study was performed to examine the availability of anaerobic digestion of the remainders caused by bacterial cellulose production process using food wastes. They maybe to be considered as others second pollution sources. Thus, this study was targeted to minimize content of organic material and to obtain more energy in those remnants using two-phase UASB reactor. The working volume of first hydrolysis fermentor was 35 L (total 55 L) and the second methane fermentor was 40 L (total 50 L). The organic loading rate of hydrolysis fermentor was 3 g-VS/L${\cdot}$day and 25,000 ppm of $COD_{cr}$ for methane fermentor. The hydraulic retention time was 18 days for hydrolysis reactor and 33 days for methane reactor. The hydrolysis reactor and methane reactor were performed at 35, 40$^{\circ}C$ respectively. For the efficient stable performance, the composition of organic wastes at each stage was as follow; Food waste with bacterial culture remnants (1 : 1), bacterial cellulose remnants, bacterial cellulose culture remnants with food wastes saccharified solids (1 : 1). When the anaerobic digestion was performed stably at each stage, the COD removal efficiency was 88, 90, 91 % respectively. At this time, methane production rate was 0.26, 0.34, $0.32m^3\;CH_4/kg-COD_{remove}$. As well as the values of anaerobic digestion at third stage were more higher than values of anaerobic digestion using food wastes. It is clearly to say that the food wastes zero-emission system constructed in our lab is more efficient way to treat and reclaim food wastes.

• Korean Journal of Environmental Agriculture
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• v.25 no.3
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• pp.247-256
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• 2006

This study has been conducted for the process of food wastes disposal using surplus capacity of established sewage treatment plant by co-digestion of fermented food wastes and sewage sludge after thermophilic acid fermentation of food wastes. The co-digestion of thermophilic acid fermented food wastes and sewage sludge was performed by semi-continous method in mesophilic anaerobic digestion reactor. It showed great digestion efficiency as the average SCOD and VS removal efficiency in organic loading rate 3.30g VS/L.d. were 74.2% and 73.6%, and the gas production rate and average methane content were 0.440 L/g $VS_{add}.d$ and 66.5%, respectively. Based on the results of this study, the co-digestion of thermophilic acid fermented food wastes and sewage sludge in sewage treatment plant is able to improve treatment efficiency of anaerobic digestion reactor and to dispose food wastes simultaneously, and was proved excellent economical efficiency comparing with any other treatment methods.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.3
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• pp.154-159
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• 2006

It is essential to understand the decomposition characteristics for developing the optimum anaerobic digestion system of organic wastes. In this study, BMP (Biochemical Methane Potential) test using serum bottle was conducted to evaluate the anaerobic degradability of fish offal. 3 different groups of fish offal including waste from mackerel and hairtail handling except viscera and fish viscera were chosen for the substrates. Grinded fish offal was transferred anaerobically to serum bottle in amounts of 50 ml, 100 ml and 150 ml, respectively. BMP test was carried out in triplicate. Cumulative methane production and methane production rate depending on incubation time were evaluated. These results varied depending on substrate characteristics. The average values of ultimate methane yield ranged between $420ml{\cdot}CH_4/g{\cdot}VS$ and $490ml{\cdot}CH_4/g{\cdot}VS$, and the methane production and degradation rate of viscera were higher than those of other parts of fish offal. According to the analysis of elemental composition, average C/N ratio of fish offal used in this study was 5.2. Theoretical ultimate methane yield calculated from elemental composition was $522ml{\cdot}CH_4/g{\cdot}VS$. Biodegradability was calculated as 0.847.

• Journal of the Korean Society of Food Culture
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• v.20 no.5
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• pp.508-515
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• 2005

The effect of glue plant(Codium fragile) on the Dongchimi fermentation was investigated by measuring physicochemical properties during fermentation at $10^{\circ}C$. Dongchimi was prepared with various levels(0, 0.5, 1.0 and 1.5%) of glue plant(Codium fragile). The pH of Dongchimi decreased slowly in all samples during fermentation. Total acidity of Dongchimi increased gradually during fermentation and total acidity of Dongchimi with glue plant(Codium fragile) was higher than that of control. Redox potentials decreased until 30 days of fermentation but increased thereafter. Reducing sugar content increased in the initial stage of the fermentation periods, and then decreased gradually. The reducing sugar content of Dongchimi with glue plant(Codium fragile) was higher than that of control. The content of total vitamin C was much higher in dongchimi with glue plant(Codium fragile). In color measurement, lightness value decreased gradually. However, redness and yellowness values increased gradually during fermentation but decreased thereafter. The content of hot water soluble pectin(HWSP) decreased as the fermentation proceeded, but the content of hydrochloric acid soluble pectin(HClSP) and sodium hexametaphosphate soluble pectin(NaSP) increased.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.1
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• pp.71-78
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• 2015

This study was performed to optimize the integrated thermal-alkali pre-treatment of flotation scum for the enhanced biodegradability. The optimum conditions of the integrated thermal-alkali pre-treatment were obtained using response surface methodology. The disintegration degree of carbohydrate (69.2%) and protein (57.3) were estimated under the optimum conditions. Although the optimum conditions were different, the disintegration degrees were similarly. A fermentative hydrogen batch test was conducted to evaluate the hydrogen production from scum with and/or without. The maximum hydrogen production from scum with pre-treatment was of 0.64 mol H2/mol hexoseadded, which about 1.4 times higher than without pre-treatment.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.4
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• pp.275-281
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• 2013

This study was conducted to increase the amount of bio-hydrogen production from microalgae(Chlorella vulgaris) in batch reactors by thermal pre-treatment. The optimization of thermal pre-treatment was conducted using statistic experimental design of response surface methodology. Two experimental parameters of temperature and reaction time were considered. The optimization condition was founded at the coded variables of <0.52, -0.07> corresponding to the experimental of heating temperature of $95.6^{\circ}C$ and reaction time of 57.9 min, respectively. Under the optimal condition, the maximum hydrogen production was predicted to 25.3mL $H_2/g$ dry cell weight (dcw), which was 9.1 times higher value of control(2.8mL $H_2/g$ dcw).

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.823-825
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• 2003

시간이 흐름에 따라 생화학 시스템이 변화하는 것을 기록한 데이터로부터 이 시스템의 상태 전이 및 시스템을 구성하는 각 생화학 물질간의 관계를 모델링하기 위한 방법으로 S-tree 구조를 제안한다. 이것은 주로 생화학 시스템의 동적 특성을 모델링 하기 위하여 연구되어 온 S-system을 나무 구조로 표현한 것이다. 본 논문에서는 진화 연산을 통해 주어진 시계열 데이터를 잘 설명하는 S-tree의 구조 및 그 변수들을 동시에 효과적으로 탐색하는 방법을 개발하였다. 이 방법에서는 구조 탐색을 위해 유전 프로그래밍(genetic programming)에서 사용되어 온 나무 구조의 교차 및 돌연변이 연산과 더불어 다양한 형태의 구조 탐색 연산자들을 도입하였고, 또한 동시에 알맞은 변수 값들을 찾기 위하여 확률적 돌연변이 연산을 통한 언덕 오르기(hill-climbing)를 수행한다. 제안된 방법을 효모의 혐기성 발효 데이터에 적용한 결과 주어진 시스템을 성공적으로 모델링할 수 있었다.