• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.316-319
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• 2011

Biopiles which offer the potential for cost-effective treatment of contaminated soils are above-ground, engineered systems that use oxygen to stimulate the growth and reproduction of aerobic bacteria for degradation of the petroleum constituents adsorbed to soil in excavated soils. This technology involves heaping contaminated soils into piles and stimulating aerobic microbial activity within the soils through the aeration and/or addition of minerals, nutrients, and moisture. Inside the biopile, microbially mediated reactions by blowing or extracting air through the pipes can enhance degradation of the organic contaminants. The influence of a aeration system on the biopile performance was investigated. Air pressure made to compare the efficiency of suction in the pipes showed that there were slightly significant difference between the two piles in the total amount of TPH biodegradation. The normalised degradation rate was, however, considerably higher in the aeration system than in the normal system without aeration, suggesting that the vertical venting method may have improved the efficiency of the biological reactions in the pile.

• The Korean Journal of Pesticide Science
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• v.2 no.2
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• pp.39-44
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• 1998

Three pesticides for paddy rice, iprobenfos, isoprothiolane, and diazinon were examined on some environmental factors, their hydrolysis, microbial degradation, and photolysis in aqueous systems. Iprobenfos was mainly degraded by microorganisms and its half-life was 5.7 days at $28^{\circ}C$ in aqueous systems. Hydrolysis of iprobenfos was accelerated by the higher temperature, but its photodegradation was accelerated by the lower pH. Isoprothiolane was rapidly decomposed by two factors, microorganisms and sunlight. The half-life of isoprothiolane by sunlight was 91 days at pH 9.0, while it was 13 days at pH 4.0 and 16 days at pH 7.2. However, it was shortened under low pH condition. In aqueous system, diazinon was degraded by all of three factors and its degradation rate was remarkably accelerated by acidic solution. Main degradation factors of iprobenfos, isoprothiolane, and diazinon in the aqueous system were investigated by microbial degradation, photolysis, and hydrolysis, respectively. The strains of microbial degradation for iprobenfos, isoprothiolane, and diazinon in the aqueous environment were identified as Pseudomonas putida, Alcaligenes xylosoxydans ss, Klebsiella planticola/ornithinllytica, respectively. The similarity rates of identity were $54.8{\sim}86.2%$ with biolog-system.

• Bulletin of the Korean Chemical Society
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• v.27 no.2
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• pp.281-285
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• 2006

Microbial fuel cells (MFC) stacked with bipolar plates have been constructed and their performance was tested. In this design, single fuel cell unit was connected in series by bipolar plates where an anode and a cathode were made in one graphite block. Two types of bipolar plate stacked MFCs were constructed. Both utilized the same glucose oxidation reaction catalyzed by Gram negative bacteria, Proteus vulgaris as a biocatalyst in an anodic compartment, but two different cathodic reactions were employed: One with ferricyanide reduction and the other with oxygen reduction reactions. In both cases, the total voltage was the mathematical sum of individual fuel cells and no degradation in performance was found. Electricity from these MFCs was stored in a supercapacitor to drive external loads such as a motor and electric bulb.

• Journal of Microbiology and Biotechnology
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• v.19 no.8
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• pp.810-817
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• 2009

The effect of cryoprotectants (maltodextrin+glycerol) and cryoprotectants+antioxidant [ascorbic acid and/or butylated hydroxytoluene (BHT)] mixtures on the survival, electrolyte leakage, and lipid degradation of freeze-dried Weissella paramesenteroides LC11 during storage was investigated and compared with that of the control (cells without additives) over a 90-day storage period at 4 or $20^{\circ}C$ in glass tubes with water activity ($a_w$) of 0.23. The survival, electrolyte leakage, and lipid degradation were evaluated through colony counts, electrical conductivity, and thiobarbituric acid reactive substances (TBARS) content, respectively. The fatty acids composition was determined by gas chromatography, in both the total lipid extract and the polar lipid fraction, and compared with that of the control after the 90-day storage period. As the storage proceeded, increases in leakage value and TBARS content, as well as a decrease in viability, were observed. After 90 days of storage, the major fatty acids found in both the total lipid extract and the polar lipid fraction were palmitic (16:0), palmitoleic (16:1), stearic (18:0), oleic (18:1), linoleic (18:2), and linolenic (18:3) acids. The survival, leakage value, TBARS content and 18:2/16:0 or 18:3/16:0 ratio were the greatest for the protected strain held at $4^{\circ}C$. Cells with the cryoprotectants+BHT mixture showed the highest percentage of survival and 18:2/16:0 or 18:3/16:0 ratio in both lipid extracts, as well as the lowest leakage value and TBARS content after the 90-day storage period. Drying cells with the cryoprotectants+BHT mixture considerably slowed down polar lipid degradation and loss of membrane integrity, resulting in improved viability during storage.

• Journal of Microbiology and Biotechnology
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• v.23 no.3
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• pp.382-389
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• 2013

Propionate is an important intermediate product during the methane fermentation of organic matter, and its degradation is crucial for maintaining the performance of an anaerobic digester. In order to understand the effect of temperature on propionate degradation, an upflow anaerobic sludge blanket (UASB) reactor with synthetic wastewater containing propionate as a sole carbon source was introduced. Under the hydraulic retention time (HRT) of 10 h and influent propionate of 2,000 mg/l condition, propionate removal was above 94% at 30-$35^{\circ}C$, whereas propionate conversion was inhibited when temperature was suddenly decreased stepwise from $30^{\circ}C$ to $25^{\circ}C$, to $20^{\circ}C$, and then to $18^{\circ}C$. After a long-term operation, the propionate removal at $25^{\circ}C$ resumed to the value at 30- $35^{\circ}C$, whereas that at $20^{\circ}C$ and $18^{\circ}C$ was still lower than the value at $35^{\circ}C$ by 8.1% and 20.7%, respectively. Microbial community composition analysis showed that Syntrophobacter and Pelotomaculum were the major propionate-oxidizing bacteria (POB), and most POB had not changed with temperature decrease in the UASB. However, two POB were enriched at $18^{\circ}C$, indicating they were low temperature tolerant. Methanosaeta and Methanospirillum were the dominant methanogens in this UASB and remained constant during temperature decrease. Although the POB and methanogenic composition hardly changed with temperature decrease, the specific $COD_{Pro}$ removal rate of anaerobic sludge (SCRR) was reduced by 21.4%-46.4% compared with the control ($35^{\circ}C$) in this system.

• Journal of Microbiology and Biotechnology
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• v.11 no.4
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• pp.607-613
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• 2001

The biodegradation rates of diesel oil by a selected diesel-degrading bacterium, Pseudomonas stutzeri strain Y2G1, and microbial consortia composed of combinations of 5 selected diesel-degrading bacterial were determined in liquid and soil systems. The diesel degradation rate by strain Y2G1 linearly increased $(R^2=0.98)$ as the diesel concentration increased up to 12%, and a degradation rate as high as 5.64 g/l/day was obtained. The diesel degradation by strain Y2G1 was significantly affected by several environmental factors, and the optimal conditions for pH, temperature, and moisture content were at pH8, $25^{\circ}C$, and 10%, respectively. In the batch soil microcosm tests, inoculation, especially in the form of a consortium, and the addition of nutrients both significantly enhanced the diesel degradation by a factor of 1.5 and 4, respectively. Aeration of the soil columns effectively accelerated the diesel degradation, and the initial degradation rate was obviously stimulated with the addition of inorganic nutrients. Based on these results, it was concluded that the major rate-limiting factors in the tested diesel-contaminated soil were the presence of inorganic nutrients, oxygen, and diesel-degrading microorganisms. To resolve these limiting parameters, bioremediation strategies were specifically designed for the tested soil, and the successful mitigation of the limiting parameters resulted in an enhancement of the bioremediation efficiency by a factor of 11.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.89-91
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• 2000

Polynuclear aromatic hydrocarbon (PAH) compounds are highly carcinogenic chemicals and common groundwater contaminants that are observed to persist in soils. The adherence and slow release of PAHs in soil is an obstacle to remediation and complicates the assessment of cleanup standards and risks. Biological degradation of PAHs in soil has been an area of active research because biological treatment may be less costly than conventional pumping technologies or excavation and thermal treatment. Biological degradation also offers the advantage to transform PAHs into non-toxic products such as biomass and carbon dioxide. Ample evidence exists for aerobic biodegradation of PAHs and many bacteria capable of degrading PAHs have been isolated and characterized. However, the microbial degradation of PAHs in sediments is impaired due to the anaerobic conditions that result from the typically high oxygen demand of the organic material present in the soil, the low solubility of oxygen in water, and the slow mass transfer of oxygen from overlying water to the soil environment. For these reasons, anaerobic microbial degradation technologies could help alleviate sediment PAH contamination and offer significant advantages for cost-efficient in-situ treatment. But very little is known about the potential for anaerobic degradation of PAHs in field soils. The objectives of this research were to assess: (1) the potential for biodegradation of PAH in field aged soils under denitrification conditions, (2) to assess the potential for biodegradation of naphthalene in soil microcosms under denitrifying conditions, and (3) to assess for the existence of microorganisms in field sediments capable of degrading naphthalene via denitrification. Two kinds of soils were used in this research: Harbor Point sediment (HPS-2) and Milwaukee Harbor sediment (MHS). Results presented in this seminar indicate possible degradation of PAHs in soil under denitrifying conditions. During the two months of anaerobic degradation, total PAH removal was modest probably due to both the low availability of the PAHs and competition with other more easily degradable sources of carbon in the sediments. For both Harbor Point sediment (HPS-2) and Milwaukee Harbor sediment (MHS), PAH reduction was confined to 3- and 4-ring PAHs. Comparing PAH reductions during two months of aerobic and anaerobic biotreatment of MHS, it was found that extent of PAHreduction for anaerobic treatment was compatible with that for aerobic treatment. Interestingly, removal of PAHs from sediment particle classes (by size and density) followed similar trends for aerobic and anaerobic treatment of MHS. The majority of the PAHs removed during biotreatment came from the clay/silt fraction. In an earlier study it was shown that PAHs associated with the clay/silt fraction in MHS were more available than PAHs associated with coal-derived fraction. Therefore, although total PAH reductions were small, the removal of PAHs from the more easily available sediment fraction (clay/silt) may result in a significant environmental benefit owing to a reduction in total PAH bioavailability. By using naphthalene as a model PAH compound, biodegradation of naphthalene under denitrifying condition was assessed in microcosms containing MHS. Naphthalene spiked into MHS was degraded below detection limit within 20 days with the accompanying reduction of nitrate. With repeated addition of naphthalene and nitrate, naphthalene degradation under nitrate reducing conditions was stable over one month. Nitrite, one of the intermediates of denitrification was detected during the incubation. Also the denitrification activity of the enrichment culture from MHS slurries was verified by monitoring the production of nitrogen gas in solid fluorescence denitrification medium. Microorganisms capable of degrading naphthalene via denitrification were isolated from this enrichment culture.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2001.06a
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• pp.103-104
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• 2001

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.102.2-102
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• 1999

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.104.1-104
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• 1999

No Abstract, See Full Text