• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.76-83
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• 2017

Biogas, combine with ever-increasing natural gas demand, has been on the center stage in South Korea for the early part of twenty first century in an effort to reduce the emission of global warming gases. With the passage of legal system of City Gas Business Law in 2014, the biogas has its place of production and distribution to consumers. However, it has a room for its technological improvements in terms of enrichment, by separating carbon dioxide and removing impurities efficiently. For these improvements, four different methane enrichment processes were tested in this study; membrane separation, water absorption, Chemical Absorption and Adsorption. A variety of operation scenarios were applied to the processes and the best practices were drawn out. The optimum process was selected based on case study results. Methane produced in this study showed 97% purity and 98% recovery rate, which meets the requirements of the City Gas quality standards.

• Journal of Plant Biotechnology
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• v.34 no.2
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• pp.81-93
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• 2007

Gas hydrates are known to form by physical interactions between host water and guest gas molecules and thus can be treated as a special type of icy materials. The gas hydrates are recently highlighted because of their use to future energy source even though they were discovered naturally in the deep-sea marine sediments a long time ago. However, the present and future urgent task is to develop the efficient and safe production technology for recovering methane from gas hydrates. Here, we propose one of potential recovery processes using swapping phenomenon occurring between gaseous carbon dioxide and methane hydrate deposits. Such a swapping process provide several technological and economical advantages over conventional processes. The carbon dioxide can be directly sequestered into methane hydrate layer and simultaneously methane can be produced with a high recovery rate more than 90%. In addition, the icy powders can be effectively used as a new medium for storing hydrogen. To increase hydrogen storage capacity the icy hydrate networks need to be redesigned to create the more empty cages in which hydrogen gas can be enclathrated. Functionalized icy materials might be used in a variety of energy and environmental fields.

• Journal of Environmental Health Sciences
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• v.22 no.1
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• pp.82-90
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• 1996

The objectives of this study were to examine the start-up method and characteristics of biomass attachment on the media in an anaerobic fluidized bed reactor(AFBR). The media adopted was the granular activated carbon which was successfully capable of adsorbing organics and biomass. The reactor was operated at 5 kg $COD/m^3\cdot day$ and 24hr of HRT. There were important problems in the AFBR's start-up, which has been reported very long and unstable. Therefore, this research was to solve the problem of the start-up and it was performed, comparing two start-up ways that were initial fluidized system and initial static-fluidized system. The results were summarized as follows: (1) On the whole initial static-fluidized system was superior to initial fluidized system in the aspects of biogas production rate, methane content and COD removal efficiency etc. (2) At the steady state methane production rate and recoverable bioenergy of initial static-fluidized system were $2.074 m^3CH_4/m^3\cdot day$, $0.488 m^3CH_4/kgCOD_{removed}\cdot day$, and 81.3kcal/day, respectively. (3) Thickness of biofilm was about $5.11 \mu m$, $\rho_{bw}$ and $\rho_{bd}$ were $1.022 g/cm^3, 0.0953g/cm^3$ respectively. (4) Biomass concentration of fluidized state was about 35 mg/g GAC. In conclusion the efficient method on the start-up of the AFBR using GAC as media was initial static-fluidized system and the period of static state needed to reach steady state was considered about twenty days.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.1
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• pp.49-56
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• 2014

This study was conducted to investigate the biodegradation characteristics of swine and cattle using anaerobic batch tests. The results showed that the maximum methane production rate($MPR_{max}$) and acclimation time(AT) of swine were 46.7 mL $CH_4/g$ VS.d and 17.2 d, respectively. The $MPR_{max}$ and AT of cattle were 56.5% and 24.0% lower than those of swine. The characteristics of anaerobic biodegradation varied with livestock species but $MPR_{max}$ and AT increased linearly with the content of lipid. The $MPR_{max}$ and AT of cattle with content of lipid were more sensitive than those of swine.

• Journal of Environmental Health Sciences
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• v.24 no.1
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• pp.54-61
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• 1998

This study was conducted in order to evaluate the treatment efficiencies of anaerobic packed and fluidized-bed biofilm and to investigate applicability in treating livestock wastewater. Biocarbonate alkalinity(BA) and volatile fatty acid(VFA) were about 3,230-3,270 mg/l, 3,790-3,126 mg/l(as CaCO$_3$) and 224-402 mg/l, 141-387 mg/l(as CH$_3$COOH), and VFA/BA ratio was about 0.069~0.12, 0.045-0.12 in packed and fluidized-bed biofilm. When COD loading rate was 6.0 kg COD/$m^3\cdot$ day in packed and fluidized-bed biofilm, methane gas production were 3.23 l/day and 4.38 l/day, respectively. In the same COD loading rate, methane gas production volumes per kg COD removal were 0.25 m$^3$ CH$_4$/kg COD$_{rm}$ and $0.28 m^3 CH_4/kg COD^{rm}$, respectively. At this time, it could be estimated that fluidized-bed biofilm was more high. In case of HRT 0.94 day(6.0 kg COD/$m^3\cdot$ day) and 11 day(0.5 kg COD/$m^3\cdot$ day), packed-bed biofilm showed 59% and 81% COD removal efficiency, respectively. While fluidized-bed biofilm showed 72% and 85% removal efficiency, respectively. It was showed that fluidized-bed biofilm was more efficient. Packed-bed biofilm was higher than fluidized in treatment efficiencies of organic matters, but required continuous treatment using combined system, because it was very exceeded over an environmental standard solidified from '96 year. In operating fluidized-bed biofilm, if farm house consider high power cost according to high circulation ratio in an economic point of view, it would have an effect that farm house use packed-bed biofilm as combined system in treating livestock wastewater.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.4
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• pp.50-61
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• 2013

In order to generate a renewable energy-Methane, anaerobic systems fed with source separated food waste from university cafeteria were studied. At first, four reactors were evaluated with same feed components; content non-mixing anaerobic reactor without leachate withdrawal/recirculation, content mixing anaerobic reactor without leachate withdrawal/recirculation, content non-mixing anaerobic reactor with leachate withdrawal/recirculation and content mixing anaerobic reactor with leachate withdrawal/recirculation. From the first study, content non-mixing anaerobic reactor with leachate withdrawal/recirculation showed the highest gas production. From further study with this system, it was observed that leachate permeation rate within anaerobic reactor was very important factor for gas generation. The higher permeation rate, the more gas production was observed. It is assumed that 1kg of gas collector weight and C/N ration above 10 in food waste may cause gas consumption in the anaerobic reactor. The gas consumption was estimated by negative pressure build-up at gas collector. The negative pressure build-up must be explained to produce Methane from Food Waste.

• Journal of Animal Science and Technology
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• v.63 no.1
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• pp.16-24
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• 2021

The suppressive effect of monensin as an ionophore-feed additive on enteric methane (CH4) emission and renewable methanogenesis were evaluated. To clarify the suppressive effect of monensin a respiratory trial with head cage was performed using Holstein-Friesian steers. Steers were offered high concentrate diets (80% concentrate and 20% hay) ad libitum with or without monensin, galacto-oligosaccharides (GOS) or L-cysteine. Steers that received monensin containing diet had significantly (p < 0.01) lower enteric CH4 emissions as well as those that received GOS containing diet (p < 0.05) compared to steers fed control diets. Thermophilic digesters at 55℃ that received manure from steers fed on monensin diets had a delay in the initial CH4 production. Monensin is a strong inhibitor of enteric methanogenesis, but has a negative impact on biogas energy production at short retention times. Effects of the activity of coprophagous insects on CH4 and nitrous oxide (N2O) emissions from cattle dung pats were assessed in anaerobic in vitro continuous gas quantification system modified to aerobic quantification device. The CH4 emission from dungs with adults of Caccobius jessoensis Harold (dung beetle) and the larvae of the fly Neomyia cornicina (Fabricius) were compared with that from control dung without insect. The cumulative CH4 emission rate from dung with dung insects decreased at 42.2% in dung beetles and 77.8% in fly larvae compared to that from control dung without insects. However, the cumulative N2O emission rate increased 23.4% in dung beetles even though it reduced 88.6% in fly larvae compared to dung without coprophagous insects. It was suggested that the antibacterial efficacy of ionophores supplemented as a growth promoter still continued even in the digested slurry, consequently, possible environmental contamination with the antibiotics might be active to put the negative impact to land ecosystem involved in greenhouse gas mitigation when the digested slurry was applied to the fields as liquid manure.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.3
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• pp.193-201
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• 2014

This study was conducted to examine the effects of defaunation (removal of live protozoa) on fermentation characteristics, degradation of ryegrass hay and $CH_4$ (methane) production by rumen microbes when incubated with plant oils (SO, sunflower oil and LO, linseed oil) in vitro. Sodium lauryl sulfate (0.000375 g/ml) as a defaunation reagent was added into the culture solution and incubated anaerobically up to 24 h at $39^{\circ}C$. pH from defaunation was increased for all treatments from 6 h incubation times (p<0.01-0.001) compared with those from fauantion. Concentration of ammonia-N from defaunation is higher than that from faunation at 3 h (p<0.001), 12 h (p<0.05) and 24 h (p<0.001) incubation times. Defaunation decreased (p<0.01-0.001) total volatile fatty acid concentration at all incubation times. Molar proportions of $C_2$ (acetate, p<0.05-0.001) and butyrate (p<0.01-0.001) were also decreased by defaunation at all incubation times. Molar proportion of $C_3$ (propionate), however, was increased by defaunation at all incubation times (p<0.001). Thus the rate of $C_2$ to $C_3$ was decreased by defaunation at all incubation times (p<0.001). Defaunation decreased ED (effective degradability) of dry matter (p<0.001) and ED of neutral detergent fiber (p<0.001) of ryegrass hay. Defaunation decreased total gas, $CH_4$ production, $CH_4$ % in total gas and $CH_4/CO_2$ at all incubation times (p<0.001). Oil supplementation decreased total gas (p<0.05-0.001), $CH_4$ production (p<0.001) and $CH_4$ % in total gas (p<0.001) compared with control at all incubation times. The result of this study showed that defaunation combined with oil supplementation may cause an alteration of microbial communities and further medicate the fermentation pattern, resulting in both reduction of degradation of ryegrass hay and $CH_4$ production. No difference, however, was observed in all the examinations between SO and LO.

• Journal of the Korean Institute of Gas
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• v.23 no.3
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• pp.7-19
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• 2019

In this study, a model was developed for estimating deliverability considering the pressure dependent permeability and predicting production profile with Material Balance Equation(MBE) for Coalbed Methane(CBM) fields. The estimated deliverability was compared with the conventional deliverability based on CBM well testing data with coefficient of determination($R^2$). As a result, the former was 0.76 and the latter was 0.69. It was confirmed that the deliverability which consider the pressure dependent permeability is more adoptable when representing the productivity of CBM fields. Through this process, in order to calculate pressure dependent permeability when well testing data exist, a method to infer reservoir pressure within the radius of investigation was proposed. The production profile of 31 gas wells was predicted for 15 years, using the estimated deliverability and the MBE. After that, the results was compared with simulation results of the literature. The simulation results did not account the pressure dependent permeability and the developed model results considered that. As the applied field permeability rised 1.17 times, field production rate was increased approximately 15% than the literature results. According to other researches, the permeability of CBM fields can be rise 6 ~ 25 times. For these cases, the production profiles may have significant difference with conventional gas fields.

• Journal of environmental and Sanitary engineering
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• v.14 no.3
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• pp.123-129
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• 1999

The utilization methods of algae biomass have been studied constantly in whole world. These are $\circled1$the wastewater treatment if waste stabilization pond and oxidation ditch etc. and $\circled2$the biosorption of heavy metals and recovery of strategic' precious metals and $\circled3$the single-celled protein production and the production of chemicals like coloring agent and $\circled4$the production of electric energy through methane gasification. The culture system also has been developed constantly in relation with such utilization method developments. In the result of experimental operation under continuous and cyclic irradiation of light, using high rate algae biomass culture pond(HRABCP), which had been made so as to be an association system with the various items which had been managed to have high efficiency for algae culture, the algae production of the 12 hours-irradiance pond was 41.48 Chlorophyll-a ${\mu}g/L$ only in spite of having the more chance of $CO_2$ synthesis to algae cell than the 24 hours-irradiance pond. This means that the energy supply required for dark-reaction of photosynthesis is very important like this. The difference of algae production between continuous and cyclc irradiation explains that the dark-reaction of photosynthesis acts on algae production as the biggest primary factor. The continuous irradiance on HRABCP made the good algae-production($1403.97{\;}{\mu}g$ Chlorophyll-a/mg) and the good oxygen-production(5.8 mg $O_2/L$) and the good solid-liquid seperation. especially, DO concentration through the oxygen-production was enough to fishes' survival.