• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.3
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• pp.102-115
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• 1990

Importance of anaerobic digestion as an energy generating device has been increased as fuel shortage becomes serieous. Several modification methods on the conventional digesters including Powdered Activated Carbon (PAC) addition and two-phase digestion were studied to enhance the gas production. This study investigated the effects of PAC on anaerobic digestion of chicken manure in terms of gas production and sludge stabilization. As a first experiment, an optimum PAC dose for efficient gas production was determined in a batch test. In semi-continuous experiments, an optimum Sludge Retention Time (SRT) at that PAC concentration and an overall substate utilization rate coefficient were investigated. A portion of gas increased by PAC addition was estimated using a substrate utilization rate coefficient of microorganisms attached on PAC. This test was performed in batch experiments using acetic acid as a substrate. The digesters for all experiments were kept 35${\pm}$ 1˚C in a heated water bath. Mixing was performed manually once a day and the produced gas was collected for daily reading. The following conclusions were made for this study. 1. Cptimum PAC concentration was 5% total solids, where gas production rate was increased by 20 percents. 2. Optimum SRT was 7.5 days. 3. Substrate utilization rate coefficient of microorganisms attached on PAC was about twice as much as that of suspended ones.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.5
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• pp.649-658
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• 2012

In this study, the influencing factors for efficient anaerobic digestion of high strength ammonia-nitrogen wastewater removal were investigated by testing biochemical methane potential test. In the influencing factors, the trace metals which could increase activity of anaerobic microorganisms, microbial concentration and types were evaluated. In the results, trace metals supplementation showed gas production amount higher than those without addition of trace metals. Among the tested trace metals, B, Ni, and Se were preferable to gas production. In the result of gas production according to the microbial concentration, the amount of gas production was proportional to the microbial concentration. In addition, the shortest lag time and the fastest gas production rate were achieved when the highest microbial concentration was tested. granule-type microorganism produced more gas than suspended-type microorganism. In conclusion, the efficient anaerobic digestion for high strength ammonia-nitrogen wastewater removal could be achieved by applying necessary trace metals injection and high concentration granule type microorganism.

• Journal of Environmental Science International
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• v.23 no.5
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• pp.853-859
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• 2014

The purpose of this study was to improve low digestibility in anaerobic digestion facility of the sewage treatment plant. To perform this research, sludge digestion and digestion gas purification facilities in sewage treatment plant was applied. In the result of this study, it was very effective for sludge reduction from the improvement of digestive efficiency. In addition, it was confirmed that high purity $CH_4$ (methane) was produced. This results can be useful as basic data to improve the low digestibility in anaerobic digestion processes.

• Microbiology and Biotechnology Letters
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• v.9 no.4
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• pp.219-223
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• 1981

Experiments on methane gas digestion were conducted to prevent livestock pollution and develop substitute energy. When about 30(w/w)% of sludge was added to cow feces, pig feces, and poultry feces and digested at 37$^{\circ}C$ for 20 days, methane gas produced per Kg of organic matter for cow feces, pig feces, poultry feces was 131, 248 and 235 l, respectively. pH decreased slightly at first but increased gradually afterwards during digestion period. When 20, 30, and 40(w/w)% of sludge were added to the mixture of cow feces (300g) and water (200g), the volumes of gas produced were 6.1, 14.5 and 13.4 l, respectively. Volume of methane gas produced from the mixture of cow feces and saw dust was much more than that from the mixture of cow feces and rice polishings. The contents of N, K, P for digestion residues were sufficient to be utilized as a fertilizer. When methane gas digestion was carried out with cow feces in a submersible pump digester the volume of methane gas produced per Kg of organic matter was 188 l. The price of total methane gas produced at this digestion was similar to that of the electric power consumed.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.3
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• pp.247-254
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• 1996

Three stages of growth of Italian ryegrass (pre-blooming, P-B; early-blooming, E-B; and late-blooming, L-B) were used to evaluate the effect of maturity on in vitro digestion of dry matter, fiber components and gas production. The rumen digestibility and gas production values were obtained by incubation of each sample in the rumen fluid of sheep for 12, 24, 36, 48 and 72 hr, respectively. The results showed that digestibility of dry matter (DM) significantly reduced (p < 0.05) as advancing maturity of the grass. Similarly, the digestibility of neutral detergent fiber (NDF) and acid detergent fiber (ADF) also significantly decreased (p < 0.05) with advancing maturity at all incubation times. However, the effect of maturity on digestibility of cellulose and hemicellulose was only detected when the samples were incubated more than 36 hr, where L-B was lower than P-B and E-B. Potential digestibility of nutrients, the maximum digestibility attainable in the rumen theoretically, was also higher at P-B than those of E-B and L-B. The amount of gas produced by microbial fermentation was closely related to the extent of DM digestion, and it was negatively correlated with advancing maturity of the grass.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1106-1115
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• 2020

Research was conducted on the production of bio-methane for city gas, from food waste digestion gas using two membrane-separation methods(4SBR and 3SDR) in a commercial plant. A purity of 98.9% can be obtained using either method. The recovery rate of methane from the digestion gas was 88.1% for 4SBR and 79.4% for 3SDR. the ratios of bio-methane production to treated digestion gas were 53.5% for 4SBR and 49.4% for 3SDR. However, the 4SBR method had a higher ratio of returned gas(56.5%), approximately twice that of 3SDR, making 3SDR the more desirable method in terms of maximum treat capacity. Therefore, 4SBR seems more economical when the digestion gas to be treated is less than 200 N㎥/day, while 3SDR is more suited to treat gas volumes of more than 240 N㎥/day. The relative deviation of each operation index, compared to mean values, was generally greater for the 4SBR method. Additionally, the correlation coefficients between major system indexes, such as bio-methane production and bio-methane draw out pressure(which is the main control measure of membrane facility) showed that these indexes are more closely related in the 3SDR method.

• Journal of Environmental Science International
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• v.9 no.1
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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.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.1
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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 Environmental Health Sciences
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• v.10 no.1
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• pp.107-117
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• 1984

This study was made to evaluate the temperature effects on anaerobic digestion of swine manure. A laboratory single-stage, high-rate, anaerobic digester was operated at 10, 20 and 30 day's HRT at the temperature of 35$\circ$C or 55$\circ$C. The conclusions from this study are as follows: (1) COD and BOD reductions were similar in both the mesophilic and thermophilic digestions. (2) With thermophilic digestion, volatile reduction increased to 67%, as compared with 60% of mesophilic digestion. With thermophilic digestion, the pH increased to 8.5 as compared with 8.0 of mesophilic digestion. With thermophilic digestion, the concentration of volatile acid increased to 763 mg/l, as compared with 250 mg/l of mesophilic digestion. While the gas was produced by mesophilic digestion at 0.74m$^3$/kg of VS fed, it increased to 0.87 m$^3$/kg VS fed by thermophilic digestion. The refractory VS was about 25% of the infiuent VS.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.3
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• pp.319-332
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• 2010

In general, wastewater treatment systems consume high-energy consumption depending on operation characteristics of the facilities. Therefore, greenhouse gas(GHG) reduction activities that are application of digestion gas, induction of renewable energy etc. are conducted to reduce energy consumption and to increase energy independence ratio. In this study, GHG reduction in wastewater treatment system identified, searched application of Clean Development mechanism(CDM) approved methodology. If the methodologies apply to GHG reduction activities such as application of digestion gas, heat pump system using the wastewater as heat source, hydropower using the methodology determined CDM applicability, otherwise through several assumptions calculated expectable GHG reduction emissions and determined CDM applicability. As a result, the order of calculated GHG reduction emission showed that collected and energy generation of digestion gas is 66,775 $tCO_2$/yr, gas engine cogeneration system is 8,182 $tCO_2$/yr, heat pump system using the wastewater as a heat source is 72,715 $tCO_2$/yr, and hydropower is 561 $tCO_2$/yr. Consequently, the order of calculated Certified Emission Reductions(CERs) benefit showed that heat pump system using the wastewater, as a heat source is 1,381 million won/yr was estimated as the highest, followed by a collected and energy generation of digestion gas is 1,268 million won/yr.