• 한국축산시설환경학회지
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• 제6권2호
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• pp.73-81
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• 2000

A two-phase anaerobic digestion system for the treatment of swine waste was constructed in a commercial hog farm. The digester system was composed of 4 major units; slurry storage pit, acidogenic digester, methanogenic digester and sedimentation pit. A biogas boiler unit was also attached to maintain the digester temperature of 37$^{\circ}C$. Substrate lading was made with 2hr-interval by pumping about 2.1$m^3$ of slurry type swine waste from the slurry pit into the acidogenic digester, which corresponds to hydraulic retention time of 4 days for the acidogenic digester and of 11 days for the methanogenic digester. Digester temperature were well maintained as the set temperature of 37$^{\circ}C$ in the methanogenic digester, while the temperature in the acidogenic digester showed around 34$^{\circ}C$. pH also showed a steady-state results of 7.3 in the acidogenic digester and of 7.6 in the methanogenic digester during the operation period. Average biogas production rate was 0.66$m^3$/$m^3$ digester volume. Reduction rate of total solid and volatile solid were 42.8% and 5.8%, respectively. Total nitrogen and ammonia nitrogen were not reduced during the anaerobic fermentation, however, most of VFAs seemed to be converted to the biogas,. These fermentation performance data may suggest that he newly developed a two-phase anaerobic digester for the swine waste treatment worked so successfully.

• Asian-Australasian Journal of Animal Sciences
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• 제27권7호
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• pp.1050-1056
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• 2014

This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature ($^{\circ}C$) at a depth of 140 cm and 180 cm, biogas production and methane ($CH_4$) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank.

• 대한토목학회논문집
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• 제2권3호
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• pp.23-32
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• 1982

본연구(本硏究)는 다절기(多節期)에는 저온(低溫)으로 하절기(夏節期)에는 고온(高溫)으로 혐기성(嫌氣性) 소화조(消化槽)를 운전(運轉)시킬 수 있는지를 검토(檢討)하기 위한 것으로 실험실(實驗室) 완전혼합형(完全混合型) 혐기성(嫌氣性) 소화조(消化槽)를 $18.5^{\circ}C$ 부터 $60^{\circ}C$까지의 11단계(段階)의 온도(溫度)에서 유기물질(有機物質)의 제거효율(除去効率) 가스생산량(生産量)을 서로 비교(比較)하였다. $35^{\circ}{\sim}40^{\circ}C$ 내외(內外)에서 BOD와 VS 제거효율(除去効率)은 각각(各各) 71%와 53%였으며 이 온도(溫度)에 있어서 가스생산량(生産量)은 주입분뇨량(注入糞尿量)의 16배(倍) 또는 $0.63m^3gas/kg$ VS fed 였다. 화조(消化槽) 유출수(流出水)를 심전(沈殿)시키면 BOD제거효율(除去効率)은 78%까지 상계(上界)하였다. 본실험(本實驗)의 결과(結果)는 $32^{\circ}$에서 $47^{\circ}C$로 운전(運轉)시킨 기존(旣存) 분뇨처리장(糞尿處理場)의 결과(結果)와 $40^{\circ}C$까지는 비교적(比較的) 잘 맞았으나 $40^{\circ}C$ 이상(以上)에서는 실험실(實驗室) 결과(結果)가 처리효율(處理効率)이나 가스생산량(生産量)으로 볼 때 양호(良好)하였다. 분뇨(糞尿)에 정화조폐액(淨化槽廢液)이나 우분(牛糞) 혼합처리(混合處理) 가능성(可能性) 검토(檢討)하였는데 1:1로 혼합처리(混合處理)시켰을 때의 BOD제거효율(除去効率)이나 가스생산량(生産量)이 분뇨(糞尿)만의 처리시(處理時)와 별로 차이(差異)가 없었다. 한편 혐기성(嫌氣性) 소화조(消化槽)의 유출수(流出水)를 희석(稀釋)없이 호기성처리(好氣性處理)도 가능(可能)한지 알아 보았는데 이때의 BOD와 SS제거효율(除去効率)은 98% 이상(以上)이었다.

• 한국농공학회지
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• 제22권1호
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• pp.53-66
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• 1980

The research work is concerned with the analytical and experimental studies on the heat transfer phenomenon around the underground concrete digester used for biogas production Systems. A mathematical and computational method was developed to estimate heat losses from underground cylindrical concrete digester used for biogas production systems. To test its feasibility and to evaluate thermal parameters of materials related, the method was applied to six physical model digesters. The cylindrical concrete digester was taken as a physical model, to which the model,atical model of heat balance can be applied. The mathematical model was transformed by means of finite element method and used to analyze temperature distribution with respect to several boundary conditions and design parameters. The design parameters of experimental digesters were selected as; three different sizes 40cm by 80cm, 80cm by 160cm and l00cm by 200cm in diameter and height; two different levels of insulation materials-plain concrete and vermiculite mixing in concrete; and two different types of installation-underground and half-exposed. In order to carry out a particular aim of this study, the liquid within the digester was substituted by water, and its temperature was controlled in five levels-35。 C, 30。 C, 25。 C, 20。C and 15。C; and the ambient air temperature and ground temperature were checked out of the system under natural winter climate conditions. The following results were drawn from the study. 1.The analytical method, by which the estimated values of temperature distribution around a cylindrical digester were obtained, was able to be generally accepted from the comparison of the estimated values with the measured. However, the difference between the estimated and measured temperature had a trend to be considerably increased when the ambient temperature was relatively low. This was mainly related variations of input parameters including the thermal conductivity of soil, applied to the numerical analysis. Consequently, the improvement of these input data for the simulated operation of the numerical analysis is expected as an approach to obtain better refined estimation. 2.The difference between estimated and measured heat losses was shown to have the similar trend to that of temperature distribution discussed above. 3.It was found that a map of isothermal lines drawn from the estimated temperature distribution was very useful for a general observation of the direction and rate of heat transfer within the boundary. From this analysis, it was interpreted that most of heat losses is passed through the triangular section bounded within 45 degrees toward the wall at the bottom edge of the digesten Therefore, any effective insulation should be considered within this region. 4.It was verified by experiment that heat loss per unit volume of liquid was reduced as the size of the digester became larger For instance, at the liquid temperature of 35˚ C, the heat loss per unit volume from the 0. 1m$^3$ digester was 1, 050 Kcal/hr m$^3$, while at for 1. 57m$^3$ digester was 150 Kcal/hr m$^3$. 5.In the light of insulation, the vermiculite concrete was consistently shown to be superior to the plain concrete. At the liquid temperature ranging from 15。 C to 350 C, the reduction of heat loss was ranged from 5% to 25% for the half-exposed digester, while from 10% to 28% for the fully underground digester. 6.In the comparison of heat loss between the half-exposed and underground digesters, the heat loss from the former was fr6m 1,6 to 2, 6 times as much as that from the latter. This leads to the evidence that the underground digester takes advantage of heat conservation during winter.

• 한국환경과학회지
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• 제2권4호
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• pp.311-316
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• 1993

3리터의 실험실 크기의 플러그 흐름의 혐기성 소화기를 사용하여 grain dust로부터 메탄가스를 생산하였다. 이 실험에서 사용한 소화기는 온도(35, 45, 55$^{\circ}C$), 체류 시간(6, 12일), 초기농도(7.8, 9.0% Total Solids)의 함수로 10가지 조건에서 실험이 행하여 졌는데, 실험 결과 55$^{\circ}C$, 6일 HRT, 7.8%TS 에서 가장 높은 메탄가스를 생산하였으며, 실험결과를 토대로 메탄가스생산 관계식을 제시하였다. 또한, 위의 실험의 조건에서는 thermophilic 의 경우가 mesophilic 경우보다 메탄가스 생성이 좋은 것으로 나타났다.

• 한국산학기술학회논문지
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• 제15권1호
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• pp.585-592
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• 2014

본 연구는 축산폐수의 혐기성 처리 시 교반의 영향에 대하여 연구자에 따라 서로 다른 결과가 보고되어 우리나라 축산폐수에 적용 시 교반의 영향을 파악할 필요가 있어 실시하였다. 4개의 혐기성 소화조를 중온 또는 고온으로 유지하면서 연속적으로 교반시키거나 교반 시키지 않고 운전하였다. 온도가 같은 경우 연속으로 교반한 반응조가 교반하지 않은 반응조의 TCOD 제거효율에 비하여 0.11-0.58% 높게 나타났다. 그리고 중온 소화조의 TCOD 제거효율이 고온 소화조의 TCOD 제거효율과 거의 같아 온도에 따른 TCOD 제거효율 간에는 큰 차이가 없었다. 연속적으로 교반한 소화조의 가스 발생량이 교반하지 않은 소화조에 비하여 1.7-4.6% 많았다. 또한 중온 소화조의 가스 발생량은 고온 소화조보다 29.1-32.1% 높고 메탄 발생량도 많았는데 이는 고온 소화조의 암모니아 저해로 인한 것으로 판단된다. 이러한 실험 결과를 종합하면 축산폐수를 혐기성으로 처리 시 중온에서 운전되고 연속적으로 교반한 반응조의 운전 조건이 더 좋은 것으로 판단된다.

• Design & Manufacturing
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• 제13권4호
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• pp.28-33
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• 2019

In this study, the flow analysis of fermentation tank, digester and dryer, which are the main equipment in environmental energy facilities, was carried out. Numerical analysis was carried out with the size of the actual plant, and 3D modeling program CATIA V5 R16, grid generation program Gambit, and general purpose flow analysis package ANSYS-FLUENT (v13) were used. Simulation results of the carrier gas flow analysis in the STD dryer using the computational fluid dynamics program showed that the carrier gas smoothly circulated between the shells of the dryer and the flow was uniformly distributed without stagnation or flow. It is also predicted that rotational flow due to shell rotation is active. The average flow velocity of carrier gas in the STD dryer was estimated to be about 0.196m / s, and the average temperature of the carrier gas was calculated to be 424K. Due to the relatively slow carrier gas velocity and high average temperature, the water content of the sludge can be effectively lowered.

• 한국농공학회논문집
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• 제50권4호
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• pp.59-66
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• 2008

Anaerobic digestion system is getting more attractive in that it produces biogas in the process of organic waste stabilization. Net energy production is important when biogas production is concerned. In this study, net energy production was evaluated with respect to biogas production and heat losses in a hypothetical digester. Under the condition of digester operation with slurry inflow of 5% of TS, additional fuel is required to maintain digester temperature during the winder season. Substrate therefore, needs to have higher VS contents through co-digestion of silage or food waste that has greater values of methane production rate. Heating input slurry is important in cold season, which covers over 80% of heating requirement. Heat recovery from digestate is valuable to reduce the use of biogas for heating. It seems desirable to minimize slurry inflow when temperature is very low. Psychrophilic digestion may be a feasible option for reducing heating requirement.

• 한국물환경학회지
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• 제27권5호
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• pp.563-571
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• 2011

The purpose of this study is to investigate the high strength ammonia oxidation of piggery wastewater. Laboratory scale reactors was operated using influent of piggery wastewater and effluent of anaerobic digester from piggery wastewater at $35^{\circ}C$ and $20^{\circ}C$. Results of various operating conditions were compared and analyzed. After analyzing the results, effluent of anaerobic digester from piggery wastewater required shorter Solid retention time (SRT) than influent of piggery wastewater. In terms of the temperature, stable ammonia removal and denitrification was achieved on the both of the condition. At the temperature of $35^{\circ}C$, nitrite conversion rate was better than $20^{\circ}C$. It can be concluded that treating the piggery wastewater using anaerobic digester on the condition of the temperature at $35^{\circ}C$ is more efficient on the nitritation of the piggery wastewater.

• 한국습지학회지
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• 제18권3호
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• pp.244-249
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• 2016

혐기 소화 상징액은 고농도 질소를 함유하고 있으며 수처리 계통으로 반송되어 하수처리장 유입 부하를 증가시킨다. 혐기 소화 상징액 내 고농도 질소를 아질산화 반응을 통해 처리하게 된다면, 경제적인 하수처리장 개조 효과를 기대할 수 있다. 본 연구에서는 혐기 소화 상징액을 이용한 장기간 실험실 규모 반응조 운전을 실시하였다. 운전 결과 암모니아성 질소 제거율 90% 이상과 아질산화율 70% 이상 효율을 보이는 운전 조건을 도출할 수 있었다. 또한 이를 바탕으로 운전 인자와 암모니아성 질소 제거 효율 및 아질산화율의 상관성을 분석하였다. 운전 결과 암모니아성 질소 제거 효율과 아질산화율은 미생물 체류시간 (SRT), 암모니아성 질소 부하 및 단위 미생물 농도 (MLSS) 당 암모니아성 질소부하와 관계가 큰 것을 확인할 수 있었다. 본 연구 결과는 향후 혐기 소화 상징액의 아질산화 반응 유도에 중요 자료로 활용될 수 있으며, 아질산화 반응의 활용성을 증가시킬 것을 기대한다.