• 한국기후변화학회지
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• 제5권4호
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• pp.359-366
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• 2014

This research was conducted to estimate methane emission from paddy field of 16 local government levels using the DNDC(DeNitrification-DeComposition) model from 1990 to 2010. Four treatments used in DNDC model for methane emission calculations were (1) midseason drainage with rice straw, (2) midseason drainage without rice straw, (3) continuous flooding with rice straw, and (4) continuous flooding without rice straw. Methane emissions at continuous flooding with rice straw were the highest ($471kg\;C\;ha^{-1}$) while were the lowest ($187kg\;C\;ha^{-1}$) at midseason drainage without rice straw. The average methane emission for 21 years was the highest ($1,406Gg\;CO_{2-eq}$.) in Jeonnam province because of its large cultivation area. Jeju province had the highest the average methane emission per unit area due to the organic content in soil.

• 청정기술
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• 제16권1호
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• pp.51-58
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• 2010

해조류를 바이오매스로 이용하는 혐기성 발효를 통해 메탄을 생성하는 연구를 수행하였다. 먼저 원소분석을 통한 다시마, 미역, 톳 등 세 종류의 바이오매스의 이론 메탄가스 전환량을 구한 결과, 분석한 세 종류의 해조류는 C 34 ~ 36%, H 5%, O 37 ~ 43%, N 2 ~ 4%, S 0.4 ~ 0.7%, ash 14 ~ 21%를 포함하고 있었으며, 이론적으로 56 ~ 60%의 메탄전환이 가능한 것으로 나타났다. 이는 g VS(고형분) 당 442 ~ 568 mL의 메탄가스를 생산할 수 있는 양이다. 생물학적메탄잠재력 (Biological Methane Potential, BMP) 시험을 통하여 실제 메탄가스를 측정한 결과, 다시마에서 최대 메탄생성수율 (52%)을 보였다. 이어서 회분식으로 메탄가스 생산에 영향을 미치는 여러 가지 인자들 (유기물 농도, pH, 염분, 입자크기, 그리고 시료전처리)에 대한 조사를 통해 최적의 메탄가스 생산조건을 구하였다. 전처리한 다시마 5 g VS/200 mL를 pH 8조건에서 염분 제거 없이 사용했을 때 이론치의 51%(197.1 mL/g VS)를 얻었고, 더욱이 습식멸균기로 해조류를 찐 경우 27% 증가한 268.5 mL/g VS 메탄가스를 생산할 수 있었다. 또한 연속반응기 (7 L 운영부피/10 L 반응기)를 이용하여 65일 간 운전한 결과 하루 최대 약 1.4 L의 메탄가스 (평균 메탄함량 70%)를 생산할 수 있었다.

• 유기물자원화
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• 제23권4호
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• pp.74-85
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• 2015

최근 들어서 국내에서도 가축분뇨를 이용한 바이오가스화 시설이 늘어나고 있다. 국내에서 운용 중인 가축분뇨 혐기소화 시설이 모두 다 혐기소화 원료로서 돼지분뇨 슬러리를 이용하고 있다. 일반적으로 돼지분뇨 슬러리는 97%내외의 물과 3% 정도의 고형물로 구성된다. 돼지분뇨 슬러리에는 옥수수 입자등과 같이 돼지가 섭취한 사료 중에서 미처 소화되지 못하고 배설되는 고형성 물질이 함유되어 있다. 입자성 물질은 혐기소화 과정에서 바이오가스 생성효과를 낮추는 요인이 된다. 따라서 본 연구에서는 기계적 분쇄 처리에 의해 고형물의 입자 크기를 감소시킴에 따른 메탄 생성효과의 변화정도를 분석하였다. 또 한편으로는 돼지분뇨 슬러리중의 고형물 농도 수준이 메탄 생성량에 미치는 영향을 분석하였다. 그리고 각각의 실험조건에서 발생된 바이오가스 중에 포함된 메탄의 농도를 분석하였다. 실험결과, 입자성 고형물을 분쇄 처리함에 따라 돼지분뇨 슬러리중의 미세 입자 농도가 증가하였다. 또한 고형물을 분쇄 처리한 경우가 분쇄하지 않은 원 슬러리를 사용하는 경우보다도 메탄 생성량과 메탄 함량이 높게 나타났다.

• 유기물자원화
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• 제17권1호
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• pp.49-57
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• 2009

본 연구에서는 UASB 반응조를 이용한 슬러리형 돈사폐수의 혐기성 소화시 암모니아 부하의 영향을 평가하였다. UASB 반응조는 $0.02{\sim}0.96kg{NH_4}^+-N/m^3/day$ 범위의 NVLR로 운전되었으며, 정상상태에서 biogas내 메탄함량은 73.3~77.9%였다. FA 농도는 메탄생성미생물의 저해 범위까지 증가하였으나, 메탄함량을 고려할 때, FA와 TA로 인한 저해는 발생하지 않았다. NVLR이 증가함에 따라 COD 제거율은 악화되었으며, $0.55kg{NH_4}^+-N/m^3/day$ 이하의 부하에서 COD 제거율을 60% 이상으로 유지할 수 있었다. NVLR이 0.09에서 $0.96kg{NH_4}^+-N/m^3/day$로 증가함에 따라, biogas의 생성량은 3.71에서 9.14L/day로 증가하였으며, COD의 메탄으로 전환율은 0.32에서 $0.20m^3CH_4/kg$으로 감소하였다. FA농도, COD 제거율, 메탄생성률 등을 고려할 때, UASB 반응조는$0.40kg{NH_4}^+-N/m^3/day$ 이하의 NVLR로 운영되어야 한다.

• 환경위생공학
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• 제23권1호
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• pp.49-56
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• 2008

Foodwaste will be able to treat is 13,000 ton/day. $18{\times}10^{13}$ won/yr are wasted with the foodwaste treatment. As a result, the initial working condition. These are given as follows : On the 1st. week, the foodwaste of the 130 ton/week(digest sludge : input foodwaste = 20 : 1) is being put into a DRANCO system by the space of 2 day. On the 2nd week, the food waste of the 130 ton/week(5 day) is being put into a DRANCO system by the space of 2 day. On the 3rd week, the foodwaste of the 130 ton/week is being put into a DRANCO system by the space of 3day. On the 4th week, the foodwaste of the 350 ton/week is being put into a DRANCO system. After that time, increase the quantity than last week is 10%. Under steady-state working condition, the methane content of the biogas is more then 55%. The $NH_3-N$ content of the digest sludge is under 3,500ppm. The VFA content of the digest sludge is under 1,500ppm. The pH is more then 8. The TS content of the digest sludge is $18{\sim}22%$. The VS content of the digest sludge is under 65%.

• Journal of Biosystems Engineering
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• 제37권4호
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• pp.233-244
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• 2012

Purpose: The kinetic evaluation was performed for swine manure (SM) degradation and biogas generation. Methods: The SM was anaerobically digested using batch digesters at feed to inoculum ratio (F/I) of 1.0 under mesophilic conditions ($36.5^{\circ}C$). The specific gas yield was expressed in terms of gram total chemical oxygen demand (mL/g TCOD added) and gram volatile solids added (mL/g VS added) and their effectiveness was discussed. The biogas and methane production were predicted using first order kinetic model and the modified Gompertz model. The critical hydraulic retention time for biomass washout was determined using Chen and Hashimoto model. Results: The biogas and methane yield from SM was 346 and 274 mL/ TCOD added, respectively after 100 days of digestion. The average methane content in the biogas produced from SM was 79% and $H_2S$ concentration was in the range of 3000-4108 ppm. It took around 32-47 days for 80-90% of biogas recovery and the TCOD removal from SM was calculated to be 85%. When the specific biogas and methane yield from SM (with very high TVFA concentration) was expressed in terms of oven dried volatile solids (VS) basis, the gas yield was found to be over estimated. The difference in the measured and predicted gas yield was in the range of 1.2-1.5% when using first order kinetic model and 0.1% when using modified Gompertz model. The effective time for biogas production ($T_{Ef}$) from SM was calculated to be in the range of 30-45 days and the critical hydraulic retention time ($HRT_{Critical}$) for biomass wash out was found to be 9.5 days. Conclusions: The modified Gompertz model could be better in predicting biogas and methane production from SM. The HRT greater than 10 days is recommended for continuous digesters using SM as feedstock.

• 한국유기농업학회지
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• 제28권4호
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• pp.605-614
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• 2020

This study was conducted to investigate the effects of TMR on in vitro rumen fermentation and methane production of goat with different forage sources. The experiment was arranged 4×2 factorial design. The different forage sources were rice straw (RS), Italian rye grass (IR), timothy (TI) and alfalfa (AL), respectively. There were two different forage : concentrate ratios such as 20:80 (20) and 50:50 (50), respectively. Therefore, totally 8 treatments were used: 1) RS20, 2) RS50, 3) IR20, 4) IR50, 5) TI20, 6) TI50, 7) AL20, and 8) AL50, respectively. The rumen fluid of goat was collected from the slaughterhouse. For fermentation parameters, ruminal pH, total gas, methane, hydrogen, ammonia nitrogen, and volatile fatty acid were determined. The pH values were within an optimal range across all treatments. Total gas productions at TI20 and AL50 were significantly greater than others (p<0.05). Methane production was significantly lower in TI and AL compared with other treatments (p<0.05). The relatively high dietary NDF content in treatments showed significantly lower methane production (p<0.05). Significant alterations treatments were detected at ammonia nitrogen concentration according to the ratio of forage : concentrate (p<0.05). AL treatment showed greater total volatile fatty acid production compared with other treatments (p<0.05). Therefore, the present study suggests that both Timothy and Alfalfa could be recommendable forage sources for goat based on results with volatile fatty acid as an energy source and methane as an index for energy loss and environmental issues. Also, the 50:50 (forage : concentrate) ratio would prefer to 20:80.

• 유기물자원화
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• 제21권4호
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• pp.50-61
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• 2013

교내 식당에서 분리 수거된 음식물류 폐기물에서 재생 에너지인 메탄가스를 생산하기 위해 혐기성 소화시스템에 대한 연구가 수행되었다. 1차 실험에서 침출수 인발/반송도 없고 혼합도 없는, 침출수 인발/반송은 없고 혼합이 있는, 침출수 인발/반송은 있고 혼합이 없는, 그리고 침출수 인발/반송은 있고 혼합이 있는 4개의 혐기성 시스템에서 침출수 인발/반송은 있고 혼합이 없는 시스템에서 가스발생이 가장 많은 것으로 나타났다. 반응조 혼합이 없고 침출수 인발/반송이 수행되는 시스템에서는 침출수의 반응조 내 침출수 유출속도가 빠른 경우에 혐기성 반응이 활발히 일어난 것으로 관찰되었다. 가스수집기 무게가 1kg이고 음식물류 폐기물 C/N비가 10이상이 되는 경우 혐기성 반응조의 가스가 소모되어 가스수집기에 부압이 걸리는 것이 관찰되었는데, 이에 대한 원인을 밝히는 것이 음식물류 폐기물에서 재생에너지를 회수하는데 필수적이다.

• Asian-Australasian Journal of Animal Sciences
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• 제25권10호
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• pp.1404-1410
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• 2012

In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima${\times}$Leucaena leucocephala (LL) (Trt 1), C. integerrima${\times}$Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana${\times}$LL (Trt 3), A. lindeliyana${\times}$GS (Trt 4), Ceiba perntandra${\times}$LL (Trt 5), C. perntandra${\times}$GS (Trt 6), Artocarpus heterophyllus${\times}$LL (Trt 7), A. heterophyllus${\times}$GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra${\times}$G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus${\times}$L. leucocephala (Trt 7) and A. heterophyllus${\times}$G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus${\times}$G. sepium (Trt 8) mixture which may be attributed with it's highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra${\times}$G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental substitution of legume forage increased gas production parameters, NH3-N, IVDMD and microbial population in the fermentation liquid. Methane production was not significantly affected by the presence of CT or different levels of CP in forage mixtures. Among non legumes, Ceiba perntandra and Artocarpus heterophyllus performed better in mixture with L. leucocephala and G. sepium.

• Asian-Australasian Journal of Animal Sciences
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• 제22권11호
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• pp.1521-1530
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• 2009

A metabolic study was conducted with four ruminally-cannulated lactating goats (Saanen, 29 weeks lactation, 65${\pm}$5 kg) in a 4${\times}$4 Latin square design with 4 dietary treatments. The goats were fed a basal mixed diet consisting of 80% concentrate and 20% chopped rye grass hay (DM basis, CON). The goats were also fed the CON diet supplemented with soybean oil at a 5% level of the concentrate (SO), the SO diet supplemented with 0.5% of sodium bicarbonate (SO-B) or the SO-B diet supplemented with 30 ppm monensin (SO-BM). The goats were housed in individual pen and the study was conducted for 8 weeks. An increased molar proportion of propionate (C3) was observed at 1 h (p<0.003) and 6 h (p<0.029) post-feeding from all the supplemented diets. Calculated methane emission was markedly decreased prior to morning feeding (p<0.01), and at 1 h (p<0.05) and 6 h post-feeding (p<0.05) in goats fed the supplemented diets. All the supplements increased (p<0.0001) cis9, trans11-CLA content in rumen fluid. Concentrations of both cis9, trans11-CLA (p<0.0001) and trans10, cis12-CLA (p<0.026) were also increased in the milk fat of lactating goats fed the supplemented diets. The SO-B and SO-BM diets further increased CLA content in goat milk compared to the SO diet. All supplements increased unsaturated (UFA, p<0.002), monounsaturated (MUFA, p<0.002) and polyunsaturated fatty acids (p<0.014) and reduced SFA to UFA ratio (p<0.023). The concentration of MUFA was even greater (p<0.002) for SO-BM than for the SO-B diet. In conclusion, feeding soybean oil (5% of concentrate) to lactating goats was a useful way to improve milk fat and to improve fatty acid profile in the milk by increasing potentially healthy fatty acids such as CLA. Supplementation of sodium bicarbonate or sodium bicarbonate with monensin to the soybean oil-based diet increased CLA content further in goat milk. Supplementation of soybean oil may be an effective method to reduce methane emission in lactating goats.