• 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.

• Journal of Soil and Groundwater Environment
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• v.9 no.3
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• pp.49-55
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• 2004

A soil enrichment LYF-1 culture from a contaminated site, which could reductively dechlorinate 900 $\mu$M (ca. 150 mg/L) of tetrachloroethylene (PCE) stoichimetrically into cis-1,2-dichloroethylene (cis-DCE), was established and characterized. The enrichment culture can use yeast extract, peptone, formate, acetate, lactate, pyruvate, citrate, succinate, glucose, sucrose, and ethanol as electron donors for dechlorination of PCE. Addition of NO$_2$$^{[-10]}$ and NO$_3$$^{[-10]}$ as alternative electron acceptors showed complete inhibition of PCE dechlorination, but S$_2$O$_3$$^{-2}$ , SO$_3$$^{-2}$ and SO$_4$$^{-2}$ had no significant effect on PCE dechlorination. The enrichment culture was attached to ceramic media in an anaerobic fixed-bed reactor. The fixed-bed reactor showed more than 99％ of PCE degradation in the range of PCE loading rate of 0.13-0.78 $\mu$moles/L/hr. The major end product of PCE dechlorination was cis-DCE.

• Korean Journal of Environmental Agriculture
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• v.19 no.4
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• pp.300-308
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• 2000

The degradation of herbicide $^{14}C-bifenox$ was studied in soils under anaerobic conditions. $^{14}C-bifenox$ was treated in silty loam and sandy loam soils, respectively at a rate of 2.1 mg/kg, and the soil was incubated under anaerobic conditions at $25^{\circ}C$ for 180 days. The mineralization, solvent extractable and non-extractable residues, degradation products of bifenox were investigated during the experiments. The relative amounts of $^{14}CO_2$ were 1.97 and 0.9% of applied $^{14}C$ in silty loam and sandy loam soils, respectively. The non-extractable residues of sandy loam soil increased dramatically up to 79.12% of applied $^{14}C$, and were higher than those of silt loam soil, suggesting physico-chemical properties and especially organic matter contributed to the difference of $^{14}C$ between two soils. The non-extractable residues were formed mainly humin fraction and increased with time. The major metabolites were nitrofen, 5-(2,4-dichlorophenoxy)-2-Nitrobenzoate, 2,4-dichlorophenoxy aniline and methyl 5-(2,4-dichlorophenoxy) anthranilate by GC/MS analysis. From the results of volatilization, mineralization and degradation of bifenox, bifenox was stable chemically and biologically in soil.

• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.4
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• pp.5-13
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• 2022

The current environmental problem is that environmental pollution is accelerating due to the generation of large amounts of waste and indiscriminate consumption of energy. Fossil fuels, a representative energy production fuel, are burned in the process of producing energy, generating a large amount of greenhouse gases and eventually causing climate change. In addition, the amount of waste generated worldwide is continuously increasing, and environmental pollution is occurring in the process of waste treatment. One of the methods for simultaneously solving these problems is the energy recovery from and reduction of organic wastes. Sewage sludge generated in sewage treatment plants has been treated in various ways since ocean disposal was completely prohibited, but the amount generated has been continuously increasing. Since the sewage sludge contains a large amount of organic materials, it is desirable to recover energy from the sewage sludge and reduce the final discharged waste through anaerobic digestion. However, most of the excess sludge is a mass of microorganisms used in sewage treatment, and in order for the excess sludge to be anaerobically digested, the cell walls of the microorganisms must be destroyed first, but it takes a lot of time to destroy the cell walls, so high rates of biogas production and waste reduction cannot be achieved only by anaerobic digestion. Therefore, the pre-treatment process of solubilizing excess sludge is required, and the thermal solubilization process is verified to be the most efficient among various solubilization methods, and high rates of biogas production and waste reduction can be achieved by anaerobic digestion after destroying cell walls the thermal solubilization process. In this study, when pretreating TS 10% thickened excess sludge through a thermal solubilization system, a study was conducted on solubilization characteristics according to retention time and operating temperature variables. The experimental variables for the retention time of the thermal solubilization system were 30 minutes, 60 minutes, 90 minutes, and 120 minutes, respectively, while the operating temperature was fixed at 160℃. The soulbilization rates calculated through TCOD and SCOD derived from the experimental results increased in the order of 12.11%, 20.52%, 28.62%, and 31.40%, respectively. And the variables according to operating temperature were 120℃, 140℃, 160℃, 180℃, and 200℃, respectively, while the operating retention time was fixed at 60 minutes. And the solubilization rates increased in the order of 7.14%, 14.52%, 20.52%, 40.72%, and 57.85%, respectively. In addition, TS, VS, T-N, T-P, NH₄⁺-N, and VFAs were analyzed to evaluate thermal solubilization characteristics of thickened excess sludge. As a result, in order to obtain 30% or more solubilization rate through thermal solubilization of TS 10% thickened excess sludge, 120 minutes of retention time is required when the operating temperature is fixed to 160℃, and 170℃ or more of operating temperature is needed when the operating time is fixed to 60 minutes.

• Journal of the Korean GEO-environmental Society
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• v.15 no.10
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• pp.15-21
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• 2014

In this study, biochemical methane potential test was conducted to estimate ultimate methane and carbon dioxide yield for anaerobic digestion and pretreatment with sewage sludge cake. Two of 0.2 % TS of sewage sludge cakes were treated with 5M NaOH or sonication of 0.51 W/mL during 30 min respectively. Another sample was treated simultaneously with NaOH and sonication in same condition. Then, initial soluble COD increased from 33.1 mg/L to 494 mg/L. After BMP test, methane production ranged from 3.12 and 84.2 mL $CH_4$ per g of Volatile Solid (VS) and 9.2 and 13.5 mL $CO_2$ per g of Volatile Solid (VS) for carbon dioxide. In other tests, injection of nutrient media or sludge supernatant produced 73.1 and 73.8 mL $CH_4$ per g of Volatile Solid (VS) and 11.2 and 13.6 mL $CO_2$ per g of Volatile Solid (VS) respectively. When BMP test finished, 62 % of initial volatile solids decreased to 33.8~45.4 %. Simultaneous pretreatment increased soluble COD, reduction rate of volatile solids and digestion efficiency than those for alkaline and ultrasonic pretreatment.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.1
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• pp.104-109
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• 2004

In this study, we stabilized the screened soil from landfills by using aerobic bioreactor and evaluated aerobic decomposition of it. Four lab-scale bioreactors (anaerobic and 1 PV/day aeration, 5 PV/day aeration, 10 PV/day aeration) filled with screened soil were operated to investigate the effect of air injection quantity on stabilization of screened soil. In case of aerobic bioreactors, the decomposition of organics in screened soil was higher than anaerobic bioreactor. According to the results of landfill gas and soil respiration test, the air injection quantity of 5 PV/day was most efficient in stabilization of screened soil.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.3
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• pp.113-118
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• 1988

Laboratory aerobic and anaerobic digesters were operated to determine the nonbiodegradable fractions in PS (Primary Sludge) and WAS (Waste Activated Sludge)from a municipal wastewater treatment plant in Seoul. Nonbiodegradable fractions were determined to be 45 to 47% in PS and 58 to 68% in WAS. Ultimate $CH_4$ gas production rates were estimated to be 0.76 for PS and $0.54m^3/kg$ VS removed for WAS. $CH_4$ contents were respectively 63% for PS and 65% for WAS.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.10-16
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• 2013

Characteristics of biological hydrogen production rate and organic acid under anaerobic fermentation process were investigated with sugar wastewater. Hydrogen production rate was higher with alkaline pre-treatment than acidic pre-treatment, resulting in 70% increment. An adequate supply of the nutrients (N or P) into raw sugar wastewater could increase hydrogen production rate. Carbohydrate degradation of the anaerobic fermentation process was not directly related with hydrogen production. Sugar wastewater with the addition of the nutrients shows 3 times higher B/A ratio than the raw sugar wastewater. B/A ratio of the wastewater with alkaline pre-treatment and nutrients addition was most higher than other samples, showing 4.02 of B/A ratio. Higher B/A ratio shows higher hydrogen production rate at each sample.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.3
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• pp.35-43
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• 2011

In this study, anaerobic biological decomposition were attempted after solubilization treatment of sewage sludge with the complex pre-treatment (acid/base treatment with ultrasonic radiation). Solubilization ratios were compared for ultrasonic treatment at acid or base condition. Solubilization effect of the complex pre-treatment was more effective at higher pH. Biological decomposition of complex pre-treated sludge was faster than non treated (raw) sludge, showing 10 times higher total gas production. Biological digestion of the sludge shows more biogas production. B/A ratio. which indicates hydrogen production potential, was 50% higher with complex pre-treated sludge than raw sludge but lactic acid or propionic acid were also detected during anaerobic decomposition process.

• KSBB Journal
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• v.21 no.6 s.101
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• pp.451-455
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• 2006

An efficient pilot scale (10 ton) three-stage methane fermentation system to digest food waste has been developed in this laboratory. This system consisted of three stages: semianaerobic hydrolysis, anaerobic acidogenesis and strictly anaerobic methanogenesis. From the secondary acidogenesis reactor, a novel strain KA4 responsible for alcohol fermentation was isolated and characterized. The cell was oval and its dimension was $5.5-6.5{\times}3.5-4.5\;{\mu}m$. This strain was identified as Saccharomyces cerevisiae KA4 by 26S rDNA D1/D2 rDNA sequence. Optimal culture temperature was $30-35^{\circ}C$. Cells were tolerant to 5% (v/v) ethanol concentration, however, were inhibited significantly by higher ethanol concentration up to 7%. The strain could grow well up to 50% (w/v) initial glucose concentration in the YM liquid medium, however, optimal concentration for ethanol fermentation was 10%. It could produce ethanol in a broad initial pH range from 4 to 10, and optimal pH was 6. In this condition, the strain converted 10% glucose to 7.4% ethanol during 24 hr, and ethanol yield was estimated to be 2.87 moi EtOH/mol glucose.