• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.498-507
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• 2008

The mixture of bentonite powder and water is generally used to maintain the stability of excavation surface during the construction of vertical cutoff walls. The filter cake on the sidewall surface is the result of filtration of slurry into the adjacent soil formation. The filter cake is believed to have a very low hydraulic conductivity compared to that of the cutoff wall. This paper evaluates hydraulic conductivities of bentonite filter cakes set up with three types of bentonites under various pressure levels. A modified fluid loss test was employed in this experiment. Theory of filtration process was reviewed to explain the procedure in the present experiment. Hydraulic conductivity of the filter cakes with consideration of the filter medium resistance was evaluated. The results of the experiment with two calculation methods and discussion are presented to show the efficiency of the modified fluid loss test.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1502-1511
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• 2008

The mixture of bentonite powder and water is generally used to maintain the stability of excavation surface during the construction of vertical cutoff walls. The filter cake on the sidewall surface is the result of filtration of slurry into the adjacent soil formation. The filter cake is believed to have a very low hydraulic conductivity compared to that of the cutoff wall. This paper evaluates hydraulic conductivities of bentonite filter cakes set up with three types of bentonites under various pressure levels. A modified fluid loss test was employed in this experiment. Theory of filtration process was reviewed to explain the procedure in the present experiment. Hydraulic conductivity of the filter cakes with consideration of the filter medium resistance was evaluated. The results of the experiment with two calculation methods and discussion are presented to show the efficiency of the modified fluid loss test.

• Geomechanics and Engineering
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• v.36 no.3
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• pp.247-258
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• 2024

Tailings are waste materials of mining operations, consisting of a mixture of clay, silt, sand with a high content of unrecoverable metals, process water, and chemical reagents. They are usually discharged as slurry into the storage area retained by dams or earth embankments. Poor knowledge of the hydro-mechanical behaviour of tailings has often resulted in a high rate of failures in which static liquefaction has been widely recognized as one of the major causes of dam collapse. Many studies have dealt with the static liquefaction of coarse soils in saturated conditions. This research provides an extension to the case of silty tailings in unsaturated conditions. The static liquefaction resistance was evaluated in terms of stress-strain behavior by means of monotonic triaxial tests. Its dependency on the preparation method, the volumetric water content, the void ratio, and the degree of saturation was studied and compared with literature data. The static liquefaction response was proved to be dependent mainly on the preparation technique and degree of saturation that, in turn, controls the excess of pore pressure whose leading role is investigated by means of the relationship between the -B Skempton parameter and the degree of saturation. A preliminary interpretation of the static liquefaction response of Stava tailings is also provided within the Critical State framework.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.280-286
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• 2012

Clean energy farming is the agricultural activity to improve an efficiency of agricultural energy use and to replace fossil fuels. This study was carried out to establish the clean energy farming system in the controlled cultivation of vegetable crop (cucumber) adopting the biogas production facility. In order to design the clean energy farming system, mass and energy balance was analyzed between the controlled cultivation system and the biogas production facility. Net yearly heating energy demands ($E_{YHED}$) of forcing and semi-forcing cultivation types were 48,697 and $13.536Mcal\;10^{-1}$ in the controlled cultivation of vegetable cucumber. To cover these $E_{YHED}$, the pig slurry of 511 and $142m^3\;10a^{-1}$ (biogas volume of 9,482 and $2,636Nm^3\;10a^{-1}$, respectively, as 60% methane content) were needed in forcing and semi-forcing cultivation types. The pig slurry of $511m^3\;10a^{-1}$ caused N 1,788, $P_2O_5$ $511kg\;10a^{-1}$ in the forcing cultivation type, and the pig slurry of $142m^3\;10a^{-1}$ caused N 497, $P_2O_5$ $142kg\;10a^{-1}$ in the semi-forcing cultivation type. The daily heating energy demand ($E_{i,DHED}$) by the time scale analysis showed the minimum $E_{i,DHED}$ of $7.7Mcal\;10a^{-1}\;day^{-1}$, the maximum $E_{i,DHED}$ of $515.1Mcal\;10a^{-1}\;day^{-1}$, and the mean $E_{i,DHED}$ of 310.2 in the forcing cultivation type. And the minimum $E_{i,DHED}$, the maximum $E_{i,DHED}$, and the mean $E_{i,DHED}$ were 5.3, 258.0, and $165.1Mcal\;10a^{-1}\;day^{-1}$ in the semi-forcing cultivation type, respectively. Input scale of biogas production facility designed from the mean $E_{i,DHED}$ were 3.3 and $1.7m^3\;day^{-1}$ in the forcing and the semi-forcing cultivation type. The maximum $E_{i,DHED}$ gave the input scale of 5.4 and $2.7m^3\;day^{-1}$ in the forcing and the semi-forcing cultivation type.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.524-531
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• 2012

The objective of this study was to investigate the organic solubilization (SCOD) and improvement of methane production for pig slurry by thermal hydrolysis. A sludge cake was pretreated by thermal hydrolysis at different reaction temperatures (200, 220, 250, $270^{\circ}C$). Ultimate methane potential (Bu) was determined at several substrate and inoculum (S/I) ratios (1:9, 3:7, 5:5, 7:3 in volume ratio) by biochemical methane potential (BMP) assay for 73 days. Pig slurry SCOD were obtained with 98.4~98.9% at the reaction temperature of $200{\sim}270^{\circ}C$. Theoretical methane potentials ($B_{th}$) of thermal hydrolysates at the reaction temperature of $200^{\circ}C$, $220^{\circ}C$, $250^{\circ}C$, $270^{\circ}C$ were 0.631, 0.634, 0.705, $0.748Nm^3\;kg^{-1}-VS_{added}$, respectively. $B_u$ of $200^{\circ}C$ thermal hydrolysate were decreased from $0.197Nm^3\;kg^{-1}-VS_{added}$ to $0.111Nm^3\;kg^{-1}-VS_{added}$ with the changes of S/I ratio from 1:9 to 7:3, and also $B_u$ of different thermal hydrolysates ($220^{\circ}C$, $250^{\circ}C$, $270^{\circ}C$) showed same tendency to $B_u$ of $200^{\circ}C$ thermal hydrolysate according to the changes of S/I ratio. Anaerobic biodegradability ($B_u/B_{th}$) of $200^{\circ}C$ thermal hydrolysate at different S/I ratios was decreased from 32.2% for S/I ratio of 1:9 to 17.6% for S/I ratio of 7:3. $B_u/B_{th}$ of $220^{\circ}C$, $250^{\circ}C$, and $270^{\circ}C$ thermal hydrolysat were decreased from 36.4% to 9.6%, from 31.3% to 0.8%, and from 26.6% to 0.8%, respectively, with the S/I ratio change, respectively. In this study, the rise of thermal reaction temperature caused the decrease of anaerobic digestibility and methane production while organic materials of pig slurry were more solubilized.

• Korean Journal of Microbiology
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• v.47 no.4
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• pp.356-363
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• 2011

The accidental releases of total petroleum hydrocarbons (TPH) due to oil spills frequently ended up with soil and ground water pollution. TPH may be degraded through physicochemical and biological processes in the environment but with relatively slow rates. In this study an attempt has been made to develop an integrated chemical and biological treatment technology in order to establish an efficient and environment-friendly restoration technology for the TPH contaminated soils. A Fenton-like reaction was employed as a preceding chemical treatment process and a bioaugmentation process utilizing a diesel fuel degrader consortium was subsequently applied as a biological treatment process. An efficient chemical removal of TPH from soils occurred when the surfactant OP-10S (0.05%) and oxidants ($FeSO_4$ 4%, and $H_2O_2$ 5%) were used. Bioaugmentation of the degrader consortium into the soil slurry led to an increase in their population density at least two orders of magnitude, indicating a good survival of the degradative populations in the contaminated soils ($10^8-10^9$ CFU/g slurry). TPH removal efficiencies for the Fenton-treated soils increased by at least 57% when the soils were subjected to bioaugmentation of the degradative consortium. However, relatively lower TPH treatment efficiencies (79-83%) have been observed in the soils treated with Fenton and the degraders as opposed to the control (95%) that was left with no treatment. This appeared to be due to the presence of free radicals and other oxidative products generated during the Fenton treatment which might inhibit their degradation activity. The findings in this study will contribute to development of efficient bioremediation treatment technologies for TPH-contaminated soils and sediments in the environment.

• Journal of The Korean Society of Grassland and Forage Science
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• v.28 no.4
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• pp.331-340
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• 2008

This study was conducted to investigate the effects of the type of swine manure on herbage productivity, the properties of soil and environmental pollution in mixed grassland. The field experiment was carried out on Livestock Breeding Station, Chonbuk in Korea from Nov. 2002 to Nov. 2005. Experimental plots were consisted of the types of swine manure, such as additional swine manure fermented with sawdust (SMFWS)+urea 50% and swine slurry (SS)+urea 50%. And then, chemical fertilizer (Urea) is used as control. DM yields of herbage were not different between chemical fertilizer and the type of swine manure. Feed values (CP, NDF, ADF, TDN) were not different between chemical fertilizer and swine manure treatments. After finishing with the experiment, Organic matter contents in soil increased. Organic matter, available phosphorous and Ca contents in swine manure treatment were higher than those of chemical fertilizer (p<0.05). $NO_3$-N and $NH_4$-N concentrations in leaching water in the mixed grassland was hardly influenced by application of swine manure and urea, whereas $NO_3$-N and $NO_3$-N levels in leaching water were less than 5 ppm.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.156-161
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• 1983

In order to find out the effect and the optimum application amount of special organic fertilizer which is granuated with fermentation residue of glutamate two field experiments were conducted with corn and chinese cabbage. The results were summarized as follows: 1. The yields of corn and chinese cabbage were slightly increased with the application of special organic fertilizer. 2. There was fertilizer injury in chinese cabbage but not in corn when applied 300kg/10a after application of standard fertilizer levels for crops with general chemical fertilizers. 3. The absorption amount of total sugar in corn plant and content of vitamin E in chinese cabbage leaves after the harvest were increased with the application of special organic fertilizer. 4. In the soil where the special organic fertilizer was used, the organic matter content after experiment increased slightly but the tendency was not constant. 5. According to the increase of the special organic fertilizer application level, the soil pH after experiment decreased. This tendency was more clear at corn cultivated area.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.671-675
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• 2012

This study was conducted to establish the BMPs (Best Management Practices) for preventing pollutant loadings from paddy rice field applied livestock liquid manure from 2008 through 2011. Cultivated paddy rice fields (Gyeonggi province, Korea) were treated with SCB (Slurry composting and bio-filtration process) liquid fertilizer. The BMPs for paddy rice field developed in this study includes: 1) the controlling a drainage water gate in paddy rice field from right after SCB liquid fertilizer application to 3 weeks after rice transplanting; 2) livestock liquid fertilizer application to paddy rice soils in 20 days before rice transplanting to encourage the utilization of liquid fertilizer; 3) preservation of surface water depth to 5 cm in a paddy field right after SCB liquid fertilizer applied to minimize a water pollution and enhance the utilization of liquid fertilizer; and 4) blocking a water gate at least for 2 days to inactivate E. coli survival. The findings of this study will provide useful and practical guideline to applicators of agricultural soil in deciding appropriate handling and time frames for preventing pollution of water quality for sustainable agriculture.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.2
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• pp.53-58
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• 2006

The Korean Ministry of Agricultural & Forestry(MAF) has designated some model areas and has supported financially to encourage sustainable farming under the environment-friendly agriculture rearing project(EARP) since 1995. This study was conducted to diagnose the project and to find ways to improve the effectiveness of EARP. The 18 areas (823 ha) such as Gyeonggi-Do, Gangwon-Do, Chungcheongbuk-Do, Chungcheongnam-Do, and Jeju-Do of 32 areas under EARP in 2004 were examined. Most of the practices implemented in EARP areas were not practical for sustainable agriculture except some equipments and facilities. It was thought that practical technologies for sustainable agriculture were more essential than equipments and facilities to improve the effectiveness of EARP. And area-specific technologies are needed to decrease environmental pollution. For example, liquefied slurry application and duck-rice farming in paddy fields near a watershed could increase the possibility of water pollution by nutrient outflow. Soil characteristics were important factors that could affect the effect of practices on environment conservation. Woodchip application and subsoil crash were not effective in coarse-textured soils. It was recommended that every practices under EARP should be re-examined in the light of the effects on environment before implementation and be evaluated by experts after completion.