• Journal of the Korea Organic Resources Recycling Association
• /
• v.25 no.1
• /
• pp.35-45
• /
• 2017

In order to improve the anaerobic digestion efficiency of the sewage sludge, the methane potential of the hydrolysate generated from the hydro-thermal reaction at 170, 180, 190, 200, 210, $220^{\circ}C$ was analyzed and the constitutional characteristics of the organic materials were estimated by dividing organic materials of hydro-thermal hydrolysate into easily biodegradable, decomposition resistant, and non-biodegradable organic materials applying the parallel first order kinetics model. The ultimate methane potential of sewage sludge hydro-thermal hydrolysate increased to 0.39, 0.39, 0.40, 0.44, 0.45, and $0.46Nm^3/kg-VS_{added}$ as hydro-thermal reaction temperature increased from 170, 180, 190, 200, 210, $220^{\circ}C$. It has been shown that the organic matter of sewage sludge is solubilized to increase the content of biodegradable organic material($VS_B$). The easily degradable organic matter($VS_e$) content was highest at hydro-thermal reaction temperature of 200 and $210^{\circ}C$, and optimum hydro-thermal reaction temperature for organic matter solubilization of sewage sludge was in the range of $200{\sim}210^{\circ}C$. In addition, the amount of biodegradable organic material($VS_B$) and easily biodegradable organic matter ($VS_e$) in the hydrolysate of sewage sludge was the highest at hydro-thermal reaction temperature of $200^{\circ}C$.

• Asian-Australasian Journal of Animal Sciences
• /
• v.27 no.3
• /
• pp.439-446
• /
• 2014

Many studies on methane ($CH_4$) and nitrous oxide ($N_2O$) emissions from livestock industries have revealed that livestock production directly contributes to greenhouse gas (GHG) emissions through enteric fermentation and manure management, which causes negative impacts on animal environment sustainability. In the present study, three essential values for GHG emission were measured; i.e., i) maximum $CH_4$ producing capacity at mesophilic temperature ($37^{\circ}C$) from anaerobically stored manure in livestock category ($B_{0,KM}$, Korean livestock manure for $B_0$), ii) $EF_{3(s)}$ value representing an emission factor for direct $N_2O$ emissions from manure management system S in the country, kg $N_2O-N$ kg $N^{-1}$, at mesophilic ($37^{\circ}C$) and thermophilic ($55^{\circ}C$) temperatures, and iii) $N_{ex(T)}$ emissions showing annual N excretion for livestock category T, kg N $animal^{-1}$ $yr^{-1}$, from different livestock manure. Static incubation with and without aeration was performed to obtain the $N_2O$ and $CH_4$ emissions from each sample, respectively. Chemical compositions of pre- and post- incubated manure were analyzed. Contents of total solids (% TS) and volatile solid (% VS), and the ratio of carbon to nitrogen (C/N) decrease significantly in all the samples by C-containing biogas generation, whereas moisture content (%) and pH increased after incubation. A big difference of total nitrogen content was not observed in pre- and post-incubation during $CH_4$ and $N_2O$ emissions. $CH_4$ emissions (g $CH_4$ kg VS-1) from all the three manures (sows, layers and Korean cattle) were different and high C/N ratio resulted in high $CH_4$ emission. Similarly, $N_2O$ emission was found to be affected by % VS, pH, and temperature. The $B_{0,KM}$ values for sows, layers, and Korean cattle obtained at $37^{\circ}C$ are 0.0579, 0.0006, and 0.0828 $m^3$ $CH_4$ kg $VS^{-1}$, respectively, which are much less than the default values in IPCC guideline (GL) except the value from Korean cattle. For sows and Korean cattle, $N_{ex(T)}$ values of 7.67 and 28.19 kg N $yr^{-1}$, respectively, are 2.5 fold less than those values in IPCC GL as well. However, $N_{ex(T)}$ value of layers 0.63 kg N $yr^{-1}$ is very similar to the default value of 0.6 kg N $yr^{-1}$ in IPCC GLs for National greenhouse gas inventories for countries such as South Korea/Asia. The $EF_{3(s)}$ value obtained at $37^{\circ}C$ and $55^{\circ}C$ were found to be far less than the default value.

• Korean Journal of Soil Science and Fertilizer
• /
• v.20 no.2
• /
• pp.147-151
• /
• 1987

This study was conducted to evaluate the effect of the liquid waste from methane fermentation on chemical components, digestible dry matter and net energy of pasture mixtures of orchard grass, tall fescue, Kentucky bluegrass and ladino clover. The total crude proteins and crude ashes increased with the application of liquid waste, but N-free extracts decreased somewhat and it didn't affect the content of crude fat and crude fiber. Amounts of neutral detergent fiber and acid detergent fiber increased with increasing application of liquid waste and the content of cellulose in cell-wall constituents decreased, but hemicellulose increased. The digestible dry matter was produced 405 kg/10a at optimum application of 42 MT/10a liquid waste compared to NPK check plot of 233 kg/10a. The starch value and net energy lactation were 291.3 KStE and 3450 MJ-NEL respectively indicating that the optimum application of liquid waste increased their values.

• Asian-Australasian Journal of Animal Sciences
• /
• v.29 no.8
• /
• pp.1136-1144
• /
• 2016

Leucaena silage was supplemented with different levels of molasses and urea to study its nutritive value and in vitro rumen fermentation efficiency. The ensiling study was randomly assigned according to a $3{\times}3$ factorial arrangement in which the first factor was molasses (M) supplement at 0%, 1%, and 2% of crop dry matter (DM) and the second was urea (U) supplement as 0%, 0.5%, and 1% of the crop DM, respectively. After 28 days of ensiling, the silage samples were collected and analyzed for chemical composition. All the nine Leucaena silages were kept for study of rumen fermentation efficiency using in vitro gas production techniques. The present result shows that supplementation of U or M did not affect DM, organic matter, neutral detergent fiber, and acid detergent fiber content in the silage. However, increasing level of U supplementation increased crude protein content while M level did not show any effect. Moreover, the combination of U and M supplement decreased the content of mimosine concentration especially with M2U1 (molasses 2% and urea 1%) silage. The result of the in vitro study shows that gas production kinetics, cumulation gas at 96 h and in vitro true digestibility increased with the increasing level of U and M supplementation especially in the combination treatments. Supplementation of M and U resulted in increasing propionic acid and total volatile fatty acid whereas, acetic acid, butyric acid concentrations and methane production were not changed. In addition, increasing U level supplementation increased $NH_3$-N concentration. Result from real-time polymerase chain reaction revealed a significant effect on total bacteria, whereas F. succinogenes and R. flavefaciens population while R. albus was not affected by the M and U supplementation. Based on this study, it could be concluded that M and urea U supplementation could improve the nutritive value of Leucaena silage and enhance in vitro rumen fermentation efficiency. This study also suggested that the combination use of M and U supplementation level was at 2% and 1%, respectively.

• KSBB Journal
• /
• v.11 no.2
• /
• pp.246-253
• /
• 1996

An obligatory methanotroph Methylosinus trichosporium OB3b was cultivated for the production of poly-${\beta}$-hydroxybutyric acid(PHB) in shake-flask using liquefied natural gas(LNG) as the sole source of carbon and energy. The maximal specific growth rate decreased by 40% using LNG compared with that obtained with pure methane. This is attributed to the inhibition by ethane and propane presents in the LNG as impurities. For the production of PHB, two-stage culture separating the production stage from the growth stage was carried out. PHB accumulation was observed after switching nutrient-sufficient to nutrient-limited condition of non-carboneous component (NO3-, PO43-, K+, Na+, Fe2+, or Mg2+). The limitation of K+ or Mg2+ resulted in relatively high PHB content, but the highest content was obtained by nitrate limitation. The optimal pH and temperature for PHB accumulation was 7.0 and $30^{\circ}C$. Under the optimal condition the maximal PHB content was about 45% after 4-day cultivation.

• Polymer(Korea)
• /
• v.34 no.2
• /
• pp.104-107
• /
• 2010

Polyurethane (PU) sheets were fabricated by the reaction of polypropylene glycol (PPG) and liquid diphenyl methane diisocyanate (L-MDI) with various trimethylol propane (TMP) contents. The $T_g$ value was varied from 34.8 $^{\circ}C$ to 49.9 $^{\circ}C$ according to the TMP content. As the content of TMP was increased from 4 to 12 wt%, the modulus of the PU sheet was increased from 322 MPa to 423 MPa, its tensile strength was increased from 10.6 MPa to 14.8 MPa, and its elongation was decreased from 62.8% to 49%. In case of acoustic properties, the sound speed of PU sheet was increased while its attenuation coefficient was decreased as the content of TMP was increased. The fabricated PU sheet was stable in water bath for 4 weeks.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.10 no.4
• /
• pp.86-95
• /
• 2002

Anaerobic digestion of municipal solid waste(MSW) is recently getting attention due to energy generation and abatement of global warming. MSW has high solid content and low nitrogen content. Its major component is cellulose and hemicellulose. The conversion rate of organic portion of MSW to methane is approximately 50%, representing $0.2m^3/kg$ VS. Long hydraulic retention time is required for high solid content and inoculum should be mixed with the feed. When MSW is digested anaerobically, maximum limit of C/N ratio is 25 and the optimum concentration of $NH_3-N$ is 700mg/L. lime and sodium bicarbonate are used to adjust pH. Excess addition of sodium bicarbonate above 3,500mg/L will cause sodium toxicity. Thermophilic anaerobic digestion is effective in the control of pathogen although its operation and maintenance is difficult. To optimize the anaerobic digestion of MSW, it is necessary to understand the mechanism of microorganims involved in anaerobic digestion.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.1
• /
• pp.104-111
• /
• 2011

In order to assess the performance of co-digester using pig slurry and food waste at the farm scale biogas production facility, the anaerobic facility that adopts the one-stage CSTR of 5 $m^3\;day^{-1}$ input scale was designed and installed under the conditions of the OLR of 2.33 kg $m^3\;day^{-1}$ and HRT of 30 days in an pig farmhouse. Several operation parameters were monitored for assessment of the process performance. The anaerobic facility was operated in three stages to compare the performance of the anaerobic co-digester. In the Stage I, that was fed with a mix of pig slurry to food waste ratio of 7:3 in the input volume, where input TS content was 4.7 (${\pm}0.8$) %, and OLR was 0.837-1.668 kg-VS $m^3\;day^{-1}$. An average biogas yield observed was 252 $Nm^3\;day^{-1}$ with methane content 67.9%. This facility was capable of producing an electricity of 626 kWh $day^{-1}$ and a heat recovery of 689 Mcal day-1. In Stage II, that was fed with a mixture of pig slurry and food waste at the ratio of 6:4 in the input volume, where input TS content was 6.9 (${\pm}1.9$) %, and OLR was 1.220-3.524 kg-VS $m^3\;day^{-1}$. The TS content of digestate was increased to 3.0 (${\pm}0.3$) %. In Stage III, that was fed with only pig slurry, input TS content was 3.6 (${\pm}2.0$) %, and OLR was 0.182-2.187 kg-VS $m^3\;day^{-1}$. In stage III, TS and volatile solid contents in the input pig slurry were highly variable, and input VFAs and alkalinity values that affect the performance of anaerobic digester were also more variable and sensitive to the variation of input organic loading during the digester operation. The biogas produced in the stage III, ranged from 11.3 to 170.0 $m^3\;day^{-1}$, which was lower than 222.5-330.2 $m^3\;day^{-1}$ produced in the stage II.

• 한국신재생에너지학회:학술대회논문집
• /
• 2008.05a
• /
• pp.610-612
• /
• 2008

Piston cores retrieved from the eastern part of the deep-water Ulleung Basin were analyzed to access the potential of hydrocarbon gas generation and natural gas hydrate (NGH) formation. Seismic data acquired in the study area were also analyzed to determine the presence of hydrocarbon gas and/or NGH, and to map their distribution. Core analyses revealed high total organic carbon (TOC) contents which favor hydrocarbon generation. The cores recovered from the southern study area showed the sufficient residual hydrocarbon gas concentrations for the formation of significant NGH. These cores also showed the cracks developed parallel to the bedding that suggest significant gas content in situ. A number of seismic blanking zones were observed on seismic data. They are identified as vertical to sub-vertical chimneys caused by the upward migration of pore fluid or gas, and containing of free gas and/or NGH. Often, they are associated with velocity pull-up structures that are interpreted to be the result of high-velocity NGH. The seismic data also showed several bottom-simulating reflectors (BSRs) that are associated with overlying NGH and underlying free gas. The distribution of blanking zones and BSRs would be impacted by the lateral differences of upward methane fluxes.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.174.1-174.1
• /
• 2011

Biogas production and utilisation is an emerging alternative energy technology. Biogas is produced from the biological breakdown of organic matter through anaerobic digestion. Biogas can be utilized for various energy services such as heating, electricity generation and vehicle fuel. Especially, to be utilized as vehicle fuel, raw biogas needs to be upgraded, that is, mainly the removal of carbon dioxide to increase the methane content, up to more than 95% in some cases, similar to the composition of fossil-based natural gas. Biogas fuelled vehicles can reduce $CO_2$ emission by between 75% and 200% compared with fossil fuels. Biomethane development is largely driven by national initiative and predominately by concerns for national air pollution and waste management. Recently, biogas projects for vehicle fuels by some companies are ongoing and Korea government also announced investment to develop biogas as a transport fuel. Therefore, the aim of this study is to examine the feasibility of biomethane as a transport fuel in Korea. In this study, we investigated quality characteristics, quality standard and upgrading technology to use vehicle fuel of transport sector in Korea.