• 한국축산시설환경학회지
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• 제20권1호
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• pp.27-34
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• 2014

This study was conducted to survey and inspect the currently operating anaerobic digestion facilities for animal manure. Recently, the number of anaerobic digestion facility for livestock manure is on the rise thanks to growing interest in developing alternative energy. A anaerobic digestion system has been constructed in large scale farms or animal manure public resource center. Currently, most animal manure anaerobic digestion facilities in operation are producing biogas from the pig slurry which contains 97% water. Methane gas can be used to operate a engine generator which then produces electricity. Anaerobic digestate, a by-product of digestion, is mostly utilized as a liquid fertilizer after curing processing. Only in a few cases, it can be discharged after wastewater treatment process. The problem of anaerobic digestate treatment is the imbalance of C/N ratio. The content of N was too high to keep it into normal process.

• 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.

• 한국환경과학회지
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• 제28권2호
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• pp.203-209
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• 2019

Organic wastewater generated from polyester manufacturing processes was selected from H company to investigate the feasibility of anaerobic digestion that produces gases including methane. Bio Methane Potential (BMP) tests were conducted to measure the gas production and methane concentration for 7 process wastewater and 2 kinds of sludges from the H company. Also, along with monitoring pH and alkalinity during the anaerobic digestion process, the concentrations of COD and 1,4-dioxane were measured with 4 different operating conditions for N Emulsion (NE) and Ethylene Glycol (EG) wastewater. The BMP tests showed that 65% of methane was produced from NE and EG wastewater. This suggests that the organic wastewater from H company can be effectively treated by an anaerobic digester by which more than 90% of COD was removed.

• 토지주택연구
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• 제2권1호
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• pp.87-92
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• 2011

음식물폐기물 처리 과정에서 발생되는 음폐수의 효율적인 처리를 위한 혐기소화공정을 선정하기 위하여, 단상 및 이상혐기소화공정을 대상으로 데모플랜트(일 5톤 처리용량)를 활용하여 성능을 비교하였다. TS, VS, tCOD 및 sCOD 처리율을 비교하여 보면 모든 항목에서 단상혐기소화공정의 처리율이 우수하였지만, 바이오가스는 오히려 이상혐기소화공정에서 더 많이 발생하였다. 이는 단상혐기소화공정의 경우 운전기간 동안 음폐수 투입량이 상대적으로 적어 처리효율은 뛰어 났지만, 음폐수 투입량 변동에 따른 바이오가스의 발생이 민감하게 반응을 한 결과로 해석된다. 이상혐기소화공정의 경우 총 COD가 상대적으로 매우 낮은 수준임에도 불구하고 바이오가스 발생량은 단상혐기소화공정보다 많이 발생되었다. 이는 음폐수 투입량이 일정하게 유지되었고, 산발효공정과 메탄발효공정이 분리되어 운영됨으로써 공정 전체가 안정적으로 운영되었기 때문인 것으로 판단된다. 음폐수처리를 위해서는 공정 선정이 중요하지만 단순 유기물처리율 비교만으로는 종합적인 평가가 어려우며, 이를 보완하기 위하여 원료성상, 투입량, 처리율, 운전기간, 바이오가스발생량 등을 종합하여 소화성능을 평가하여야 할 것이다.

• 한국환경과학회지
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• 제9권1호
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• pp.75-80
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• 2000

Kinetic data for the acid phase anaerobic digestion were presented in this study and the constants were determined with acid production rate and gas production rate. Process models based on continuous culture theory were used to describe the characteristics of the acid forming microorganisms and to enable further development toward utilization of the process in a more rational manner. Acid phase digestion can be separated with appropriate manipulation of hydraulic retention time in anaerobic digestion. Kinetic analysis of data from the various hydraulic retention times using a phase specific model obtained form the acid phase indicated maximum specific growth rate of 0.40/h, saturation constant of 2,000mgCOD.$\ell$, yield coefficient of 0.35 mgVSS/msCOD utilized and decay constant of 0.04/h for the acid production rate. Similar analysis of data for the gas production rate indicated maximum specific growth rate of 0.003/h, saturation constant of 2,200mgCOD/$\ell$, yield coefficient of 0.035 mgVSS/mgCOD utilized and decay constant of 0.06/h.

• 한국환경농학회지
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• 제30권1호
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• pp.31-36
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• 2011

축산농가에서 발생되는 돈분 슬러리의 처리 능력을 평가하기 위하여 Full-scale의 단상 혐기성 소화조에서 중온소화와 고형물 체류시간을 20일로 하여 연속식으로 운전하면서 성능평가 및 특성연구를 실시하였다. 운전기간 중 알칼리도는 약 4,000 mg/L(3,500~9,000 mg/L as $CaCO_3$)이였고, 소화조내의 pH는 7.5~8.0 범위로 약간 높은 경향이었으나 pH는 안정적이었다. 바이오가스의 발생량은 OLR 1.2 $g{\cdot}COD/L{\cdot}day$에서 0.69 L/L/day의 바이오가스를 생산하였고, 제거된 COD를 바탕으로 계산된 메탄가스 발생량은 63% 수준이였다. 생산된 바이오가스 중 메탄가스 함량은 65~70%이었고, CO2는 약 30% 전후였으며, 열병합 발전을 실시하였을 때 총전력요구량의 50~75% 수준을 공급하였다. 또한 발전기 부하가 5~9 kW시 평균 1 kWh의 전력을 생산하기 위한 바이오가스 소모량은 약 1.8 $m^3$이였다. 따라서 실제 규모의 plant에서 약 500일간 운전한 결과 유입되는 돈분 슬러리의 TS 농도에 상관없이 소화조 내에 일정 농도의 유기물을 확보할 수 있었고, 바이오가스의 발생량은 일반적인 축산분뇨 가스 발생량 보다 높게 나타나 단상 혐기성 소화공정으로 고효율 처리가 가능한 것으로 나타났다.

• 상하수도학회지
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• 제31권1호
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• pp.13-19
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• 2017

Relatively low efficiency in anaerobic digestion process is mainly caused by unproper mixing method. In this study, tray motion type agitator was applied in actual anaerobic digestion tank in order to improve the digestion efficiency, equalize the flow velocity distribution and energy saving. The impeller of tray motion type agitator was reciprocated vertically. Gas lift type agitator and tray motion type agitator appears almost same mixing efficiency include digestion rates. However, tray motion type agitator have shown that lower energy consumption compared to the conventional gas lift type agitator. Implementation of tray motion type agitator in the anaerobic digestion tanks contributed to the stabilization of mixing environment, efficiency and energy efficiency of the tank.

• Journal of Biosystems Engineering
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• 제39권4호
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• pp.366-376
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• 2014

Purpose: In the process of anaerobic digestion, stirring of the digester and feeding of organic waste into the digester have been considered important factors for digestive efficiency. The objective of this study was to determine the most appropriate conditions for both stirring interval of the digester and organic feeding frequency in order to improve anaerobic digestion performance. Methods: A 5-L anaerobic digester was used to conduct continuous batch tests to process swine manure and food waste. Four different stirring intervals of the digester were used: 5 min/h, 10 min/2 h, 15 min/3 h, and 20 min/4 h. Results: The application of swine manure to the digester every 5 min/h resulted in the highest production of biogas as well as the highest removal rates of volatile solids (VS) and total chemical oxygen demand. Stirring the digester with a mixture of swine manure and food waste at intervals of 5min/h and 10min/2 h produced the highest biogas yields of 515.3 mL/gVS and 521.1 mL/gVS, respectively. To test different supply frequencies, organic waste was added to the digester in either a 12-hor 24-h cycle. The 24-h cycle produced 1.5-fold greater biogas production than that during the 12-h cycle. Conclusions: Thus, from the above results, to optimize anaerobic digestion performance, the ideal stirring condition must be 5min/h for swine manure feeding and 10min/2h for co-digestion of food waste and swine manure in a 24-h cycle.

• 한국환경보건학회지
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• 제23권3호
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• pp.40-49
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• 1997

In Korea, naked barley and tapioca are main raw materials for the production of fermentation ethyl alcohol, and one million drums bf 95% fermentation ethyl alcohol is produced per year by use of them. Stillage of alcoholic fermentation is mostly digested by methane fermentation process, and methane gas occured if methane fermentation process is recovered and mixed with fuel to decrease 25-30% for total fuel used in factories. In the anaerobic digestion process of naked barley stillage, supplement of nutrients is necessary to slove the problems caused by inhibitory materials contained if stillage and deficiency of nutrients. Therefore, the objective of this study was to examine why the anaerobic digesters using the naked barley distillery wastewater have shown the poor digestability frequently and how to control it. As the poor digestion was supposed to be occurred by the lack of iron as trace nutrient, the experiments were carried out to find out the optimum dosage and the way of addition of iron and to assess the quantitative evaluation of the type of iron in digesters. Initially, bottle test as batch digesters and lab-scaled continuous flow digesters were used in order to determine the digestion characteristics with tapioca and naked barley distillery wastewater. According to the results of batch tests, the poor digestion was caused by volatile fatty acids and could be improved by adding of calcium. The activity of the methanogenic bacteria were increased remarkably when the iron was added to the digester in the form of mixture with substrates.

• 상하수도학회지
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• 제26권6호
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• pp.825-831
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• 2012

The retrofitting of a thickening unit process is widely considered in municipal wastewater treatment plants in Korea to enhance the anaerobic digestion efficiency. The authors examined the effect of feed concentration (2-34.1 g VS/L) and feed to microorganism (F/M) ratio (0.50-1.35 g VS/g VS) on anaerobic batch digestion of sewage sludge. Methane yield over 90 mL $CH_4/g$ $VS_{feed}$ was found at a feed concentration in the range of 12-26 g VS/L and a F/M ratio below 0.6 g VS/g VS. A high F/M ratio decreased methane yield and rate with oragnic acid accumulation. As sudden increase of sewage sludge concentration prior to anaerobic digestion would jeopardize the digester performance due to the rasied F/M ratio, gradual increase of the sludge feed concentration or an additional biomass retention in the digester is recommended.