• Microbiology and Biotechnology Letters
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• v.31 no.2
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• pp.197-200
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• 2003

In oil-contaminated environments, anaerobic biodegradation of toluene depended on the concentration and distribution of terminal electron acceptor as well as the physicochemical properties such as DO concentration, redox potential and pH. This study showed the anaerobic biodegradation of toluene in two different soils by using nitrate reduction, ferric iron reduction, sulfate reduction and methanogensis. Toluene degradation rates in the soil samples taken from rice filed and tidal mud flat by nitrate reduction were higher than those by other processes. Tho soil samples from the two fields were enriched for 130 days by providing toluene as a sole carbon source and nitrate or sulfate as a terminal electron acceptor. The toluene degradation rates in the enriched denitrifying consortia obtained from the rice field and tidal mud flat soil were 310.7 and 200.6 $\mu$mol$ L^{-1}$ / $d^{-1}$, respectively. The toluene (legradation rates in the enriched sulfate-reducing consortia from the fields ranged fi-om 149.1 to 86.1$\mu$mol $L^{-1}$ / $d^{-1}$ .

• Journal of Korean Society of Water and Wastewater
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• v.24 no.5
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• pp.603-608
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• 2010

More than 8 millions of chemical have been used for human activities and lots of chemicals can not be degraded by microbial activities in this world. To show the biodegradability of a chemical, biodegradability index (B.I.) is suggested using aerobic biodegradability by $BOD_5$/COD, anaerobic biodegradability by methane potential (M.P.) and toxicity by the luminiscent bacteria. In this study, PVA (polyvinyl alcohol), HEC (hydroxy ethyl cellulose), 2,4,6-TCP (tri-chloro phenol) and 2,4-DCP (di-chloro phenol) are used for test chemicals. Though they show little toxicity, PAV and HEC have low B.I. because they are polymers having high molecular weight. That means that there are no bacteria that has enzyme to degrade polymer molecules. Also, anaerobic treatment is suggested better than aerobic treatment from B.I. 2,4,6-TCP and 2,4-DCP show high toxicity and have low B.I. Their low biodegradabilities seem to be originated from their toxicities. If B.I. is used in wastewater treatment, better treatment process can be suggested and finally it can lead our society to make more environment-friendly chemicals.

• Journal of Korean Society on Water Environment
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• v.21 no.4
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• pp.403-409
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• 2005

Methyl tert-butyl ether (MTBE) contamination in groundwater often coexists with benzene, toluene, ethylbenzene, and xylene (BTEX) near the source of the plume. Then, groundwater contamination problems have been developed in areas where the chemical is used. Common sources of water contamination by BTEX and MTBE include leaking underground gasoline storage tanks and leaks and spills from above ground fuel storage tanks, etc. In oil-contaminated environments, anaerobic biodegradation of BTEX and MTBE depended on the concentration and distribution of terminal electron acceptor. In this study, effect of electron acceptor on the anaerobic biodegradation for BTEX and MTBE-contaminated soil was investigated. This study showed the anaerobic biodegradation of BTEX and MTBE in two different soils by using nitrate reduction, ferric iron reduction and sulfate reduction. The soil samples from the two fields were enriched for 65 days by providing BTEX and MTBE as a sole carbon source and nitrate, sulfate or iron as a terminal electron acceptor. This study clearly shows that degradation rate of BTEX and MTBE with electron acceptors is higher than that without electron acceptors. Degradation rate of Ethylbenzene and Xylene is higher than that of Benxene, Toluene, and MTBE. In case of Benzene, Ethylbenzene, and MTBE, nitrate has more activation. In case of Toluene and Xylene, sulfate has more activation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.467-470
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• 2003

Leaking underground storage tanks are a major source of groundwater contamination by petroleum hydrocarbons. Aerobic bioremediation has been highly effective in the remediation of many fuel releases. However, Bioremediation of aromatic hydrocarbons in groundwater and sediments is ofen limited by the inability to provide sufficient oxygen to the contaminated zones due to the low water solubility of oxygen. Nitrate can also serve as an electron acceptor and results in anaerobic biodegradation of organic compounds via the processes of nitrate reduction and denitrification. Because nitrate is less expensive and more soluble than oxygen. it may be more economical to restore fuel-contaminated aquifers using nitrate rather than oxygen. And denitrifying bacteria are commonly found in the subsurface and in association with contaminated aquifer materials. These studies have shown that BTEX and MTBE can be degraded by the nitrate-amended microcosms under aerobic and anaerobic conditons. Biodegradation of the toluene and ethylbenzne compounds occurred very quickly under denitrifying conditions. MTBE, benzene and p-xylene were recalcitrant under denitrifying conditions in this study, But finally Biodegradaton was observed for all of the test compounds.

• 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.

• Journal of Soil and Groundwater Environment
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• v.21 no.3
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• pp.88-94
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• 2016

The simultaneous biodegradation between MTBE (Gasoline additives) and BTEX (Benzene, Toluene, Ethyl-benzene, o-Xylene, m-Xylene, p-Xylene) was achieved within a competitive inter-relationship, with not only electron accepters such as nitrate, sulfate, and iron(III) without oxygen, but also with electron donors such as MTBE and BTEX. Preexisting indigenous microorganisms from a domestic sample of gasoline contaminated soil was used for a lab-scale batch test. The result of the test showed that the biodegradation rate of MTBE decreased when there was co-existing MTBE and BTEX, compared to having just MTBE present. The growth of indigenous microorganisms was not affected in the case of the MTBE treatment, whereas the growth of the microorganisms was decreased in combined MTBE and BTEX sample. This may indicate that an inhibitor related to biodegradation when BTEX and MTBE are mixed will be found. This inhibitor may be found to retard the anaerobic conditions needed for efficient breakdown of these complex carbon chain molecules in-situ. Moreover, it is also possible that an unknown competitive reaction is being imposed on the interactions between MTBE and BTEX dependent on conditions, ratios of mixture, etc.

• Journal of Korean Society of Water and Wastewater
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• v.9 no.2
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• pp.127-135
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• 1995

The purpose of this study was to more fully evaluate the potential for chlorophenol degradation in anaerobic sludge. The pH effects on the ring cleavage of phenol and dechlorination of monochlorophenol isomers and dichlorophenl isomers. This study results are as follows ; Each of the monochlorophenol isomers were degraded in anaerobic sludge. The relatives rates were 2-Chlorophenol > 3-Chlorophenol > 4-Chlorophenol. Biodegradation results for the dichlorophenol isomers in anaerobic sludge are such as 2,3-dichlorophenol and 2,5-dichlorophenol was reductively dechlorinated to 3-chlorophenol, 2,4-dichlorophenol to 4-chlorophenol, 2,6-dichlorophenol to 2-chlorophenol. The two dichlorophenol isomers which did not contain an ortho Cl substituent 3,4-dichlorophenol and 3,5-dichlorophenol were persistent during the 6-week incubation. The rate of dechlorination was enhanced by the presence of a Cl group ortho, rather than para, to the site of dechlorination.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.4
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• pp.54-62
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• 1997

Disposal of blue crab wastes represents a significant problem to processors, who are limited with respect to acceptable disposal alternatives. Anaerobic bioconversion technology was investigated to determine an environmentally sound and economic disposal method for these wastes. In the study ultimate methane yield for total crab solid waste was $0.180m^3/kg$ VS added and biodegradation rate constant was $0.15day^{-1}$. Methane yield of the bench-scale reactor operated on similar feedstock was $0.189m^3/kg$ VS added and biodegradation rate constant was $0.06day^{-1}$. These results indicate that anaerobic bioconversion of blue crab wastes was technically feasible. Use of anaerobic bioconversion technology can be an attractive option for blue crab processing waste management. The by-product methane gas could be used for maintainign a number of processing operations (i.e., heat for cooking, or keeping temperature of digester constant).

• Journal of Soil and Groundwater Environment
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• v.20 no.4
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• pp.15-21
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• 2015

Anaerobic biodegradation of diesel with coexisting heavy metals (Pb) was monitored in batch mode. Two different groups of the indigenous bacteria from a site contaminated with diesel and lead were used in this research: the first group was composed of a single species and the second group was composed of several species. The effect of heavy metals on the microbial population was monitored and confirmed the biodegradation mechanism in each combined contaminant. Growth of the microorganisms in 21 days was observed Diesel > Diesel + Pb > Diesel + Cu > Diesel + Pb + Cu > Diesel + Cr > Diesel + Pb + Cr. Indigenous microorganisms showed the adaptation in the Pb contaminate. Interactive toxic effect using AMES test observed larger synergistic effect than antagonistic in Diesel + Cr and Diesel + Pb + Cr. Therefore, the main effects of diesel biodegradation in the present of heavy metals are likely to exist other factors as well as toxic of heavy metals. This is a necessary part of the future studies.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.3
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• pp.46-51
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• 2008

The traditional view of the fate of lignin under anaerobic conditions is that it is recalcitrant because molecular oxygen is required for depolymerization. The presence of lignin is apparently the most important factor affecting the biodegradability of ligneous materials. The initial step in the degradation of ligneous material to smaller intermediates is catalyzed by enzymes secreted by microorganisms and is generally regarded as the rate limiting step in the microbial mineralization of organic matter. Biochemical methane potential (BMP) test, typically used to assess anaerobic biodegradability of liquid wastes with added nutrients and bacteria, have been adapted to assess initial biodegradation of ligneous material under anaerobic conditions. A method based on selective inhibition of microorganism activity, by 3% toluene, has been used to measure using the initial degradation rate of ligneous material and the accumulation of lignin-derived compounds.