• 한국물환경학회지
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• 제35권4호
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• pp.332-339
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• 2019

A comparative study on the anaerobic digestion efficiency according to the temperature change was conducted considering the characteristics of domestic food wastes with high water content of about 80 % or more. The substrate was tested for anaerobic digestion efficiency in two substrates, a liquid component separated naturally from food waste and food waste itself. In the anaerobic digestion experiments, the digestion efficiency was the highest at $55^{\circ}C$ (thermophilic temperature). However, the digestion efficiency at $45^{\circ}C$(middle high temperature) was lower than that at $35^{\circ}C$(mesophilic temperature). The comparison of general food wastes anaerobic digestion requiring 30 days of hydraulic retention time to the liquid component indicated a stable digestion efficiency even after 15 days of hydraulic retention time.In the experiments conducted on food waste, the digestion efficiency at $55^{\circ}C$ was higher than that at $35^{\circ}C$. When the food waste, especially the liquid component originating from food waste, is treated by anaerobic digestion method, the mesophilic temperature and thermophilic temperature conditions are more favorable in the digestion efficiency than the middle high temperature ($45^{\circ}C$). However, when applying thermophilic or mesophilic temperature anaerobic digestion process operation in the field, the amount of energy input should be considered.

• 한국환경보건학회지
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• 제10권1호
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• pp.107-117
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• 1984

This study was made to evaluate the temperature effects on anaerobic digestion of swine manure. A laboratory single-stage, high-rate, anaerobic digester was operated at 10, 20 and 30 day's HRT at the temperature of 35$\circ$C or 55$\circ$C. The conclusions from this study are as follows: (1) COD and BOD reductions were similar in both the mesophilic and thermophilic digestions. (2) With thermophilic digestion, volatile reduction increased to 67%, as compared with 60% of mesophilic digestion. With thermophilic digestion, the pH increased to 8.5 as compared with 8.0 of mesophilic digestion. With thermophilic digestion, the concentration of volatile acid increased to 763 mg/l, as compared with 250 mg/l of mesophilic digestion. While the gas was produced by mesophilic digestion at 0.74m$^3$/kg of VS fed, it increased to 0.87 m$^3$/kg VS fed by thermophilic digestion. The refractory VS was about 25% of the infiuent VS.

• 한국물환경학회지
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• 제21권5호
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• pp.490-495
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• 2005

Since there are very limited numbers of thermophilic anaerobic digesters being operated, it is often difficult to start up a new one using sludge from an existing reactor as a seed. However, for obvious reasons it seems few attempts have been made to compare the start-up performance of thermophilic anaerobic digestion using different sources of seed sludges. The purpose of this study was to evaluate the start-up performance of anaerobic digestion using aerobic Waste Activated Sludge (WAS) from a plant and mesophilic Anaerobic Digested Sludge (ADS) as the seed source at both mesophilic ($35^{\circ}C$) and thermophilic ($55^{\circ}C$) temperatures. In this study, two experiments were conducted. First, thermophilic anaerobic reactors were seeded with WAS (VSS = 4,400 mg/L) and ADS (VSS = 14,500 mg/L) to investigate start-up performance with a feed of acetate as well as propionate. The results show that WAS started to produce $CH_4$ soon after acetate feeding without a lag time, while ADS had a lag time of 10 days. When the feed was changed to propionate, WAS removed propionate down to below the detection limit of 10 mg/L, while ADS removed little propionate and produced little $CH_4$. Second, in order to further compare the methanogenic activity of WAS and ADS, both mesophilic and thermophilic reactors were operated. WAS acclimated to anaerobic conditions shortly and after acclimating it produced more $CH_4$ than ADS. WAS at mesophilic temperature biodegraded acetate at the same rate as for thermophilic. However WAS at mesophilic temperature biodegraded propionate at a much faster rate than at thermophilic. WAS as the seed source of anaerobic digestion resulted in much better performance than ADS at both mesophilic and thermophilic temperatures for both acetate and propionate metabolism.

• 한국환경과학회지
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• 제15권9호
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• pp.897-905
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• 2006

This study has been conducted to investigate biodegradation characteristics and optimum mixing ratio for co-digestion with thermophilic acid-fermented food waste and sewage sludge using batch anaerobic digester. As the basis operating conditions for anaerobic digestion, the reaction temperature was controlled $35{\pm}1^{\circ}C$ and stirrer was set 70rpm. Thermophilic acid-fermented food waste and sewage sludge were mixed at the ratio of 10:0, 7:3, 5:5, 3:7, 0:10 and 5;5(food waste : sewage sludge) as the influent substrates. In results of co-digestion according to mixing ratio of thermophilic fermented food wastes and sewage sludge in batch mesophilic anaerobic digestion reactor, $385mL\;CH_4/g\;VS_{added}$ of methane production rate at 1:1 mixing ratio was more than that of any other mixing ratios. Compared with $293mL\;CH_4/g\;VS_{added}$ of methane production rate at 1:1 mixing ratio of food wastes and sewage sludge, pretreatment of food wastes by thermophilic acid fermentation was more effective in co-digestion with sewage sludge.

• 상하수도학회지
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• 제18권4호
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• pp.515-521
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• 2004

Anaerobic digestion has many advantages over the more conventional aerobic treatment processes such as low levels of excess sludge production, low space (area) requirements, and the production of valuable biogas. The purpose of this study was to evaluate the effect of organic loading rate of anaerobic digestion on thermophilic($55^{\circ}C$) and mesophilic($35^{\circ}C$) conditions. Fluorescent in situ hybridization (FISH) method was also used to study the microbial community in the reactors. The stabilizing time in mesophilic anaerobic reactors was shorter as approximately 20 days than 40 days in the thermophilic anaerobic reactors. The amount of methane production rate in anaerobic reactors was independent of the concentrations of supplied substrates and the amount of methanogens. When the microbial diversity in the mesophilic and thermophilic reactors, which had been treated with acetate-based artificial wastewater, were compared, it was found that methanogenesis was carried out by microbial consortia consisting of bacteria and archaea such as methanogens. To investigate the activity of bacterial and archaeal populations in all anaerobic reactors, the amount of acetate was measured. Archaea were predominant in all reactors. Interestingly, Methanothrix-like methanogens appeared in mesophilic anaerobic reactors with high feed substrate concentrations, whereas it was not observed in thermophilic anaerobic reactors.

• 한국환경과학회지
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• 제33권2호
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• pp.121-129
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• 2024

The study investigated the effect of thermo-alkaline pretreatment on the solubilization of polyhydroxybutyrate (PHB) and its potential to enhance of thermophilic anaerobic digestion, focusing on biochemical methane potential (BMP) and methane production rate, using two different particle sizes of PHB (1500 ㎛ and 400 ㎛). Thermo-alkaline pretreatment tests were conducted at 90 ℃ for 24 hours with varying NaOH dosages from 0-80% (w/w). BMP tests with untreated PHB exhibited methane production ranging from 150.4~225.4 mL CH₄/g COD and 21.5~24.2 mL CH₄/g VSS/d, indicating higher methane production for smaller particle sizes of PHB, 400 ㎛. Thermo-alkaline pretreatment tests achieved a 95.3% PHB solubilization efficiency when 400 ㎛ PHB particles were treated with 80% NaOH dosage at 90 ℃ for 24 hours. BMP tests with pretreated PHB showed substantial improvement in thermophilic anaerobic digestion, with an increase of up to 112% in BMP and up to 168% in methane production rate. The results suggest that a combined pretreatment process, including physical (400 ㎛ PHB particles) and thermo-alkaline (90 ℃, 40-80% NaOH dosage, and 24 hours reaction time), is required for high-rate thermophilic anaerobic digestion of PHB with enhanced methane production.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.514-517
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• 2009

Anaerobic biodegradability(AB), which can be determined with the ultimate methane yield by the decomposition of organic materials, is one of the important parameters for the design and the operation of anaerobic digestion plant. In this study, Biochemical Methane Potential(BMP) test has been carried out to evaluate the methane yield of agro-industrial biomasses such as cattle manure, Italian ryegrass(IRG), Oats, Rye and Barley as the forage crops, Rush, the sludges produced from milling and slaughterhouse wastewater treatment plant(SMWTP, SSWTP). In the condition of thermophilic anaerobic digestion, the ultimate methane yield and anaerobic biodegradability of forage crops ranged from 0.367 to $0.452LCH_4$/gVS of methane yield with AB having the range of about 77.0 to 87.3%. On the other hand, that of other substrate showed low figures compared with the forage crops because of low VS content and C/N ratio. Therefore, the forage crops could be used as a good substrate to produce much more the methane in anaerobic digestion.

• 유기물자원화
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• 제16권1호
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• pp.31-38
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• 2008

동물 사체 처리가 축산업에 큰 부담이 되고 있다. 본 연구의 목적은 고온 혐기성 소화에 의한 동물 사체의 처리 타당성을 검토하는데 있다. 고기와 내장을 사용하여 수행된 회분식 실험 결과 동물 사체가 혐기성 고온 조건에서 분해 가능함이 확인되었다. 초기 기질 volatile solids (VS) 1.5~7.7% 조건에서 유기물 제거 효율과 메탄 생성 모두 52.7~58.5%, 220~243 ml/g VS의 양호한 효율을 보였다. 그러나 연속 실험에서는 VS 2.5% 이상의 조건에서 혐기성 미생물의 활동이 암모니아 독성에 의해 저해됨이 발견되었다. 암모니아가 동물 사체 내의 단백질이 분해되는 과정에서 생성되며 혐기성 조건에서 분해되지 않으므로, 암모니아 농도를 낮추는 방법은 희석이 유일하다고 판단된다. 따라서 고온 혐기성 소화를 적용할 시, 동물 사체의 단독 처리 보다는 질소 농도가 상대적으로 낮은 다른 폐수 또는 폐기물과의 혼합 소화를 고려하는 것이 타당할 것으로 사료된다.

• 대한토목학회논문집
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• 제7권3호
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• pp.1-11
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• 1987

중온소화(中溫消化)와 고온소화(高溫消化)의 차이점을 보다 명확히 규명하기 위하여 소화(消化)의 정지(停止)를 포함하는 폭넓은 실험을 행하였다. 연구결과, 정상소화(正常消化)와 소화조해(消化阻害)를 구분짓는 한계체류시간(限界滯留時間)이 존재하여, 중온(中溫)에서는 10일(日), 고온(高溫)에서는 5일(日)부근이었고 그 이하(以下)의 체류시간(滯留時間)에서는 소화(消化)의 조해(阻害)가 급격하게 발생하였는데 고온(高溫)에 비하여 중온(中溫)에서의 조해(阻害)정도가 매우 컸다. 중온소화(中溫消化)의 한계체류시간이상(限界滯留時間以上)에서는 소화(消化)상태가 거의 유사하였으나, 그이하(以下)의 체류시간(滯留時間)에서는 고온소화(高溫消化)가 월등히 양호(良好)하였으며, 고온(高溫)에서는 중온(中溫)에 비하여 소화(消化)슬러지발생량(發生量)이 감소하는 동시에 소화(消化)슬러지의 침강속도(沈降速度)가 크게 증가하고 여과비저항(濾過比抵抗)은 감소하였다. 한편 반응속도(反應速度)는 소화(消化)에 마치는 온도(溫度)와 체류시간(滯留時間)의 영향을 나타내는 데 유효하였다. 또한 온도(溫度)에 관계없이 반응속도(反應速度)가 증가함에 따라 가스발생속도(發生速度)가 선형적(線形的)으로 증가하였고 그 상관관계(相關關係)는 중온(中溫)과 고온(高溫)에서 거의 일치하였다.

• 상하수도학회지
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• 제26권1호
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• pp.21-27
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• 2012

This study evaluated the performance of a thermophilic two-phase anaerobic digestion (TTPAD) coupled with membrane process treating garbage leachate. The pilot-scale treatment system is consisted of thermophilic acidogenic reactor (TAR) and thermophilic methanogenic reactor (TMR) coupled with an ultrafiltration (UF) membrane unit. The hydraulic retention time of TAR and TMR were 4 and 20 days, respectively. Effluent TCOD and SCOD of the TTPAD were $25\;{\pm}\;6\;and\;12\;{\pm}\;3$ g/L, respectively, and the corresponding TCOD and SCOD removal efficiencies were 77% and 81%, respectively. Propionate was major acids as 75% in the effluent. Scum formation was not observed in TTPAD, which might be resulted from complete lipid degradation. However, TTPAD was appeared to be sensitive to free ammonia toxicity. The UF membrane was operated with constant pressure filtration at average TMP 1.3 atm. Permeate flux had a range of 15-30 $L/m^2/hr$. With UF membrane, TCOD removal increased from 77% to 93%, and this SS free effluent would be beneficial to subsequent processes such as ammonia stripping.