• 한국물환경학회지
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• 제30권5호
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• pp.559-567
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• 2014

Since the ocean dumping of organic wastes is prohibited under the London Convention, the need for land treatment of food waste leachate (FWL) has significantly been growing in recent years. This study was conducted to use thermal solubilization to turn FWL into a form that can easily be degraded during the anaerobic digestion process, thereby reducing the percentage of solids and increasing the production of methane. To derive the optimal operating conditions of thermal solubilization, a laboratory-scale reactor was built and operated. The optimal reaction temperature and time turned out to be $190^{\circ}C$ and 90 min, respectively. The BMP test showed a methane production of 465 mL $CH_4/g$ $COD_{Cr}$ and a biodegradation rate of 90.1%. The production of methane rose by about 15%, compared with no the application of thermal solubilization. To reduce the solid content of FWL and improve the methane production, therefore, it may be helpful to apply thermal solubilization to pre-treatment facilities for anaerobic digestion.

• Asian-Australasian Journal of Animal Sciences
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• 제24권1호
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• pp.130-136
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• 2011

Methane is known to be one of the major greenhouse gases. On a global scale, livestock farming may contribute 18% of total greenhouse gas emissions. Though methane contribution is less than 2% of all the factors leading to global warming, it plays an important role because it is 21 times more effective than carbon dioxide. Methane emission is a direct result of the fermentation process performed by ruminal microorganisms and, in particular, the archael methanogens. Reducing methane emission would benefit both ruminant production and the environment. Methane generation can be reduced by electron-sink metabolic pathways to dispose of the reducing moieties. An alternative way for methane control in the rumen is to apply inhibitors against methanogens. Generating methane from manure has considerable merit because it appears to offer at least a partial solution to two pressing problems-environmental crisis and energy shortage. An obvious benefit from methane production is the energy value of the gas itself. Control of methane emission by rumen microbes in Korea has mainly been focused on application of various chemicals, such as BES and PMDI, that inhibit the growth and activity of methanogens in the rumen. Alternatives were to apply long-chain polyunsaturated fatty acids and oils with or without organic acids (malate and fumarate). The results for trials with methane reducing agents and the situation of biogas production industries and a typical biogas plant in Korea will be introduced here.

• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2145-2149
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• 2018

The formation of methanol directly from methane and steam was observed over Cu ion-exchanged mordenite. Furthermore, the continuous production of methanol was achieved by co-feeding methane and steam over Cumordenite. The methanol production rate was comparable to that reported in the stepwise process in which activation, methane reaction, and extraction of methanol were carried out separately.

• 상하수도학회지
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• 제28권1호
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• pp.55-60
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• 2014

Food waste leachate (FWL) is a serious pollutant waste coming from the food waste recycling facilities in Korea. FWL has a high organic matter content and high COD to nitrogen (COD/N) ratio, which can disturb efficient methane production in the anaerobic digestion of FWL. In the present study a microalga, Clorella vulgaris (C.V), was used as co-substrate for the FWL anaerobic digestion in order to supply nutrients, decrease the COD/N ratio and increase its methane yield. Different co-digestion mixtures (COD/N ratios) were studied by using biochemical methane potential test and modified Gompertz equation for kinetic study. Mixed substrate of FWL and C. vulgaris in the co-digestion clearly showed more the biomethane yield than the sole substrates. The maximum methane production, 827.7 mL-$CH_4$/g-VS added, was obtained for COD/N ratio of 24/1, whereas the highest improvement of methane yield was found for COD/N ratio of 15/1.

• 한국환경농학회지
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• 제27권2호
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• pp.145-149
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• 2008

Anaerobic co-digestion of swine manure and food waste for biogas production was performed in serum bottles at various volatile solids(VS) contents and mixing ratios of two substrates(swine manure:food waste=$100:0{\sim}0:100$). Through kinetic mode of surface methodology, the methane production was fitted to a Gompertz equation. The ultimate methane production potential of swine manure alone was lower than that of food waste regardless of VS contents. However, it was appeared that maximum methane production potentials in 80 : 20 of the mixing rate at VS 3% was enhanced at 144.7%, compared to its only swine manure. The potential increased up to 815.71 ml/g VS fed as VS concentration and food composition increased up to 3.0% and 20%, respectively. The ultimate amount of methane produced had significantly a positive relationship with that of methane yield rate. Overall, it would be strongly recommended that feeding stocks use 20% of mixing ratio of food waste based on VS 3% contents when operating the anaerobic reactor on site at $35^{\circ}C$ if not have treatment of its anaerobic waste water.

• 상하수도학회지
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• 제10권4호
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• pp.111-118
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• 1996

Effects of $CO_2$ partial pressure($pCO_2$) on the characteristics of methane production rate and organic matter degradation in anaerobic digestion were investigated by using anaerobic chemostat type reactors at $35{\pm}1^{\circ}C$, at the HRT of 7days. The $pCO_2$ of the reactors was controlled in the range from 0.1 to 0.8 atm. Since the $pCO_2$ in an uncontrolled condition was about 0.4atm, $N_2$ was added for the reactors controlled of $pCO_2$ of between 0.1 and 0.4atm. At $pCO_2$ of 0.5 atm, the methane production rate was approximately 20% more that in an uncontrolled condition of $pCO_2$. Based on the carbon mass balance, it was concluded that methane production was related to the increment of removal organic carbon and consumption of $CO_2$. At $pCO_2$ of 0.5atm, the methane production by the increment of removal substrates increased 13.6%, on the orther hand, hand, the methane production by the conversion of $CO_2$ to methane increased 6.4%.

• 한국습지학회지
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• 제8권4호
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• pp.41-47
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• 2006

전 지구적 기후변화로 인하여 습지에서 일어나는 다양한 종류의 생지화학적인 순환에 큰 변화가 관측되고 있다. 특히, 갯벌의 경우 온도변화에 의한 직접적인 환경변화 뿐 아니라 해수면의 상승과 강수량의 변화라는 요인에 의해 간접적인 영향도 받을 것으로 예측된다. 본 논문에서는 온도와 해수의 염도 변화에 따라 갯벌에서 발생하는 메탄양의 변화를 실험실 규모의 실험을 통하여 규명하고자 했다. 시료는 겨울철 강화도 동검도 갯벌에서 채취하여 2 종류의 실험을 수행하였다. 첫 번째 실험에서는 0-5 cm, 5-10 cm 깊이의 토양을 자연 상태의 염도와 50 % 희석한 염도 조건 하에서 20 일간 배양하며 2일 간격으로 메탄 발생량을 측정하였다. 두 번째 실험에서는 5-10 cm 깊이의 토양을 $5^{\circ}C$, $15^{\circ}C$ 에서 자연 상태의 염도와 50 % 희석한 염도 조건 하에서 31일간 배양하며 발생하는 메탄의 양을 하루 간격으로 측정하였다. 첫 번째 실험의 결과 5-10 cm 깊이의 토양에서 메탄이 더 많이 발생하며 염도의 영향은 배양 후반부로 가면서 크게 나타남을 알 수 있었다. 두 번째 실험 결과에서는 $15^{\circ}C$에서 $5^{\circ}C$에서 보다 더 많은 메탄이 발생하였고, 50 % 희석한 염도 조건에서 자연 상태의 염도 조건에서 보다 많은 메탄이 발생하는 것을 관찰할 수 있었다. 이러한 결과는 갯벌에서의 메탄 생성율은 온도 상승과 해수의 화학적 특성의 변화에 따라 많은 영향을 받음을 보여준다. 또한 전 지구적 기후변화로 야기될 온도나 해수 염도의 변화가 메탄의 발생에 영향을 미쳐, 생물학적 되먹임 기작에도 변화가 일어날 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제19권9호
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• pp.1283-1290
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• 2006

The effect of substituting potato by-products based silage (PBS) for concentrates on ruminal fermentation, methane production and nitrogen utilization in Holstein steers was evaluated. Three growing Holstein steers ($490{\pm}19kg$, initial body weight) were used in a $3{\times}3$ Latin square experiment with three experimental diets in which PBS was included at (1) 0, (2) 19 and (3) 27%, on a dry matter basis, replacing concentrates and wheat bran. Increasing replacement levels of PBS slightly increased dry matter (DM), organic matter (OM), NDF and ADF intakes by the steers (p<0.05). Inclusion of PBS at 19% increased crude protein (CP) digestibility of the experimental diets compared with the control (p<0.05). Substitution with PBS increased ADF digestibility and nitrogen retention (p<0.05), but did not affect energy retention. Energy loss as methane ranged between 5.0 and 6.1% of the total gross energy intake. There were no significant differences in carbon dioxide and methane production among all PBS levels, while daily methane production numerically increased with PBS inclusion. Substituting PBS for concentrates did not significantly affect ruminal pH and ammonia N concentration. Total VFA concentration, VFA molar proportions and blood metabolites were also unaffected by PBS replacement. These results suggest that substitution of PBS up to 27% of diet dry matter did not significantly increase methane production and was equal or superior to concentrates in ADF digestibility and nitrogen retention for growing steers.

• Asian-Australasian Journal of Animal Sciences
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• 제28권2호
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• pp.188-199
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• 2015

Nineteen tanniferous browse plants were collected from South Africa to investigate their digestibility, gas production (GP) characteristics and methane production. Fresh samples were collected, dried in forced oven, and ground and analyzed for nutrient composition. In vitro GP and in vitro organic matter digestibility (IVOMD) were determined using rumen fluid collected, strained and anaerobically prepared. A semi-automated system was used to measure GP by incubating the sample in a shaking incubator at $39^{\circ}C$. There was significant (p<0.05) variation in chemical composition of studied browses. Crude protein (CP) content of the species ranged from 86.9 to 305.0 g/kg dry matter (DM). The neutral detergent fiber (NDF) ranged from 292.8 to 517.5 g/kg DM while acid detergent fiber (ADF) ranged from 273.3 to 495.1 g/kg DM. The ash, ether extract, non-fibrous carbohydrate, neutral detergent insoluble nitrogen, and acid detergent insoluble nitrogen and CP were negatively correlated with methane production. Methane production was positively correlated with NDF, ADF, cellulose and hemi-cellulose. Tannin decreased GP, IVOMD, total volatile fatty acid and methane production. The observed low methanogenic potential and substantial ammonia generation of some of the browses might be potentially useful as rumen manipulating agents. However, a systematic evaluation is needed to determine optimum levels of supplementation in a mixed diet in order to attain a maximal depressing effect on enteric $CH_4$ production with a minimal detrimental effect on rumen fermentation of poor quality roughage based diet.

• Asian-Australasian Journal of Animal Sciences
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• 제20권8호
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• pp.1305-1318
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• 2007

On a global scale agriculture and in particular enteric fermentation in ruminants is reported to produce about one fourth (21 to 25%) of the total anthropogenic emissions of methane ($CH_4$). Methane is produced during the anaerobic fermentation of hydrolyzed dietary carbohydrates in the rumen and represents an energy loss to the host besides contributing to emissions of greenhouse gases into the environment. However, there appears to be uncertainty in the $CH_4$ estimation from livestock due to the limited availability of data to document the variability at the farm level and also due to the significant impact of diet on the enteric $CH_4$ production. The methane mitigation strategies require robust prediction of emissions from rumen. There are many methods available which would be suitable for measuring $CH_4$ produced from the various stages of animal production. However, several factors need to be considered in order to select the most appropriate technique like the cost, level of accuracy required and the scale and design of the experiments to be undertaken. Selection of any technique depends on the accuracy as each one has its advantages and disadvantages. Screening of mitigation strategies may be evaluated using individual animal before large-scale trials on groups of animals are carried out. In this review various methods for the estimation of methane production from ruminants as well as for the determination of methane production potential of ruminant feeds are discussed. The advantages and disadvantages of the methods starting from respiration chamber, ventilated hood, facemask, sulphur hexafluoride ($SF_6$) tracer technique, prediction equations and meteorological methods to in vitro methods are detailed.