• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.989-996
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• 2009

In this study, the effects of biofilter media type (three different activated carbons and anthracite), empty bed contact time (EBCT) and temperature on the removal of four aldehyde species (formaldehyde, acetaldehyde, glyoxal and methylglyoxal) in BAC filters were investigated. Experiments were conducted at three water temperature (5, 15 and $25^{\circ}C$) and four EBCTs (5, 10, 15, and 20 min). The experimental results indicated that the coal based BAC retained more bacterial biomass on the surface of the activated carbon than the other BACs, and increasing EBCT or increasing water temperature also increased the four aldehyde species removal in BAC filters. To achieve above 80% of removal efficiency for four aldehyde species in a BAC filter, above 15 min EBCT at $5^{\circ}C$ and 10 min EBCT at above $15^{\circ}C$ were required. The kinetic analysis indicated a first-order reaction rate for the biodegradation of four aldehyde species at various water temperatures. Data obtained from the BAC filters at various temperatures were also used to evaluate pseudo first-order rate constants for four aldehyde species. The half-lives evaluated for formaldehyde, acetaldehyde, glyoxal and methylglyoxal in the coal-based BAC ranging from 0.89 to 3.19 min, from 0.75 to 3.35 min, from 2.16 to 4.72 min and from 1.49 to 3.86 min, respectively, could be used to assist water utilities in designing and operating BAC filters.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.487-494
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• 2003

2,3-Dihydroxybiphenyl 1,2-dioxygenase (23DBDO), an enzyme of the biphenyl biodegradation pathway encoded by the bphC gene of Comnmonas sp. SMN4, was expressed and purified using column chromatographies. SDS-PAGE of purified 23DBDO showed a single band with a molecular mass of 32 kDa, which was consistent with the data from the gel filtration chromatography (GFC). The purified enzyme exhibited a maximum 23DBDO activity at pH 9.0 and was stable at pH 8.0. The enzyme showed maximum activity at $40^{\circ}C$ and maintained activity at $30^{\circ}C$ for 24 h. Kinetic parameters represented by Michaelis-Menten constants such as $K_m\;and\;V_{max}$ values for various substrates were determined by Lineweaver-Burk plots: The purified enzyme 23DBDO from Comamonas sp. SMN4 had the highest catalytic activity for 2,3-dihydroxybiphenyl and 3-methylcatechol, and had very poor activity with catechol and 4-methylcatechol.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.70-76
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• 2003

The benzene removal characteritics of the polyurethane (PU) biofilter immobilized with S. maltophilia T3-c, that could efficiently degrade benzene, was investigated. Maximum capacity to eliminate benzene was maintained at $100-110g{\cdot}m^-3{\cdot}h^-1$ when space velocity (SV) ranged from 100 to $300 h^-1$ -1/, however, it decreased sharply to $55 g{\cdot}m^-3{\cdot}h^-1^$ as SV increased to $400 h^-1$. The critical elimination capacities that guaranteed $90\%$ removal of inlet loading of the PU biofilter were determined to be 70,30, and $15 g{\cdot}m^-3{\cdot}h^-1$ at SV 100,200, and $300 h^-1$, respectively. Based on the result of a kinetic analysis of the PU biofilter, maximum benzene elimination velocity ($V_m$) was $125 g{\cdot}m^-3^\;of\;PU{\cdot}h^-1$ and saturation constant ($K_m$) was $0.22 g{\cdot}m^-3^$ of benzene ($65{\mu}{\cdot}I^-1$). This study suggests that the biofilter utilizing S. maltophilia T3-c and polyurethane is a very promising technology for effectively degrading benzene.

• Fisheries and Aquatic Sciences
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• v.15 no.2
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• pp.91-97
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• 2012

To isolate a nonylphenol (NP)-degrading bacterium, we isolated a single colony from the NP-degrading microbial consortium SW-3, which was previously isolated from an aqueous environment. Ten colonies that exhibited different cell morphologies were isolated and the strains were named SW-3-A, -B, -C, -D, -E, -F1, -F2, -G, -H, and -I. The ability of isolates to degrade NP was evaluated by kinetic analysis by the constant of NP degradation rate ($k_1$) and the half-life time of NP degradation ($t_{1/2}$). SW-3-F1, -F2, -G, and -I strains were superior at degrading NP. The $k_1$ and $t_{1/2}$ values of the four strains were sixfold higher and one-sixth lower, respectively, than those of the consortium strain. Additionally, SW-3-F1, -G, and -I strains were tested for their ability to degrade NP during coculture. NP degradation by coculture with a combination of all three strains was inferior to that of culture conducted with single isolates, suggesting that the three strains are antagonistic toward each other during NP degradation.

• Journal of Environmental Health Sciences
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• v.31 no.5 s.86
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• pp.423-430
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• 2005

This research was performed to evaluate the effectiveness of one- and dual-stage recycled-water systems in slurry bioreactor treatment for coal tar-contaminated soil. Silty loam soil was used for this research. Coal tar and 14 target PAHs (Polycyclic Aromatic Hydrocarbons) concentration in the soil were determined with gas chromatography. There was no significant difference between removal efficiencies of one- and dual-stage recycled water systems in case of about 4,000 mg coar tar/kg. However, the dual-stage system increased significantly the removal efficiency in case of about 20,000 mg coar tar/kg and the first-order kinetic constant of the system was over 1.5 times higher than that of one-stage recycled water system. 3-Ring compounds in PAHs was removed completely within 30 days of operation. Coar tar was removed in over 96% through biodegradation and removed in about 4% by evaporation. High correlation coefficient($r^2=0.91$) was found between water solubility and removal efficiency of the cyclic compounds.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.17 no.1
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• pp.41-47
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• 1981

The characteristics of septic tank sludges were investigated and the kinetic coefficients in the aerobic biodegradation were evaluated from bach treatability tests. Using an unbiased statistical method, the estimated values, k (substrate removal rate coefficient) =0. 0175hr-1 at 17\ulcornerC, K. (Michaelis Menten constant) = 248mg/ e, a (cell yield coefficient)=0.625, and Kd (cell decay coefficient:' =0. 00192hr-1 were obtained based on biodegradable COD(mg/ \ulcorner) and volatile suspended solids(mg/\ulcorner). The relationship between COD and BOD, COD (mg/\ulcorner) =2. 1 BOD(mg/\ulcorner) +250, also was established for the septic tank sludges. Dilution was inevitable for the grit removal because of the high viscosity of the sludges. An aerobic activated sludge process rather than anaerobic processes was recommended for the removal of soluble organics after the removal of grit and suspended solids. A multi-stage activated sludge process was adapted for this highly concentrated and not easily-degradable waste. It was estimated that a four-stage activated sludge process would require 40 hours retention time compared to 92 hours for a single-stage process, 52 hours for a double-stage process, and 46 hours for a three stage process in order to achieve an effluent quality of 84mg/ e COD( 40mg/ e BOD) with about 4, OOOmg/ \ulcorner MLSS from an influent quality of I, 500mg/ t COD(714mg/.e BOD), while multi-stages beyond four stage would not save the required retention time significantly.

• Microbiology and Biotechnology Letters
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• v.30 no.4
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• pp.395-401
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• 2002

Methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) have been widely used as solvents in various industries. Biodegradation of MEK and MIBK by Pseudomonas putida KT-3, which could utilize MEK or MIBK as a sole carbon source, was characterized, and the cosubstrate interaction in MEK/MIBK mixture was also studied. Within the range of initial MEK concentration (from 0.5 to 5.5 mM), an increased substrate concentration increased the specific degradation rate of MEK by P putida KT-3 (from 3.15 to 10.58 mmol/g DCW$\cdot$h), but the rate sightly increased at 11.0 mM of initial MEK concentation (11.28 mmol/g DCW$\cdot$h). The similar degradation rates of MIBK (4.69-4.92 mmol/g DCW$\cdot$h) were obtained at more than 3.0 mM of initial MIBK concentation. Kinetic analysis on the degradation of MEK/MIBK mixture by P. putida KT-3 showed that MEK or MIBK acted as a competitive inhibitor. Maximum degradation rate ($V_{max}$), saturation constant ($K_{m}$) and inhibition constant ($K_{1}$) were as follows: $V_{max,MEK}$=12.94 mmol/g DCW$\cdot$h; $K_{m,MEK}$=1.72 mmol/L; $K_{l,MEK}$=1.30 mmol/L; $V_{max,MIBK}$=5.00 mmol/g-DCW$\cdot$h; $K_{m,MIBK}$=0.42 mmol/L; $K_{l,MEK}$=0.77 mmol/L.

• Journal of Microbiology and Biotechnology
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• v.26 no.11
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• pp.1951-1964
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• 2016

1,4-Dioxane-degrading bacterial consortia were enriched from forest soil (FS) and activated sludge (AS) using a defined medium containing 1,4-dioxane as the sole carbon source. These two enrichments cultures appeared to have inducible tetrahydrofuran/dioxane and propane degradation enzymes. According to qPCR results on the 16S rRNA and soluble di-iron monooxygenase genes, the relative abundances of 1,4-dioxane-degrading bacteria to total bacteria in FS and AS were 29.4% and 57.8%, respectively. For FS, the cell growth yields (Y), maximum specific degradation rate ($V_{max}$), and half-saturation concentration ($K_m$) were 0.58 mg-protein/mg-dioxane, $0.037mg-dioxane/mg-protein{\cdot}h$, and 93.9 mg/l, respectively. For AS, Y, $V_{max}$, and $K_m$ were 0.34 mg-protein/mg-dioxane, $0.078mg-dioxane/mg-protein{\cdot}h$, and 181.3 mg/l, respectively. These kinetics data of FS and AS were similar to previously reported values. Based on bacterial community analysis on 16S rRNA gene sequences of the two enrichment cultures, the FS consortium was identified to contain 38.3% of Mycobacterium and 10.6% of Afipia, similar to previously reported literature. Meanwhile, 49.5% of the AS consortium belonged to the candidate division TM7, which has never been reported to be involved in 1,4-dioxane biodegradation. However, recent studies suggested that TM7 bacteria were associated with degradation of non-biodegradable and hazardous materials. Therefore, our results showed that previously unknown 1,4-dioxane-degrading bacteria might play an important role in enriched AS. Although the metabolic capability and ecophysiological significance of the predominant TM7 bacteria in AS enrichment culture remain unclear, our data reveal hidden characteristics of the TM7 phylum and provide a perspective for studying this previously uncultured phylotype.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1287-1291
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• 2009

The genes of cyanide hydratase(CHT), a kind of nitrilases whichhydrolyze cyanide to formamide were extracted from N. crassa and A. nidulans, the two fungal strains. The recombinant forms of the CHT originated from N. crassa and A. nidulans were prepared with N-terminal hexahistidine purificationtags or no tags, and expressed in E. coli. The enzymes were purified using immobilized metal affinity chromatography. They were compared according to their pH activity profiles, and kinetic parameters. The N. crassa CHT has the wider pH range of activity above 50% and three-fold higher turnover rate (6.6 ${\times}$ $10^8$ $min^{-1}$) than the A. nidulans, meanwhile the CHT of A. nidulans has the higher $K_m$ value. Expression of CHT in both N. crassa and A. nidulans were induced by the presence of KCN, regardless of any presence of nitrogen sources. Max. 82% of KCN was degraded in 60 min for biological degradation tests.

• Economic and Environmental Geology
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• v.36 no.5
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• pp.375-380
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• 2003

This study was carried out 1) to investigate the pH effect on solubilization of phenanthrene by biosurfactant in aqueous system and 2) to evaluate the pH effect on the biodegradation rate of phenanthrene in the presence and the absence of the biosurfactant by phenanthrene degraders. Tween 80, which is a chemically synthesized surfactant, showed greater solubilizing capacity than rhamnolipid. The solubilization capacity can be expressed as a MSR(molar solubilization ratio=moles of organic compounds solubilized per mole of surfactant). The calculated MSR of Tween 80 and rhamnolipid were 0.1449 and 0.0425 respectively. The kinetic study of phenanthrene solubilization by rhamnolipid showed that solubilization mechanism could reach equilibrium within 24 hours. Addition of 240 ppm rhamnolipid solution, which concentration is 4.3 times of Critical Micelle Concentration(CMC), caused 9 times solubility enhancement compared to water solubility. The highest solubilities were detected around a pH range of 4.5-5.5. Changes in apparent solubility with the changes in pH are possibly related to the fact that the rhamnolipid, an anionic surfactant, can form different structures depending on the pH. Two biodegradation experiments were performed in the absence and the presence of rhamnolipid, with the cell growth investigated using a spread plate method. The specific growth rates at pH 6 and 7 were higher than at the other pH, and the HPLC analysis data, for the total phenanthrene loss, confirmed the trends in the $\mu$(specific growth rate) values. In presence of rhamnolipid, maximum $\mu$ values shifted from around pH 5 which showed maximum enhancement of solubility in the abiotic experiment, compared to the $\mu$ values obtained without the biosurfactant. In this study, the increase in the observed specific grow rate(1.44 times) was not as high as the increase in solubilization(5 times). This was supported by the fact all the solubilized phenanthrene is not bioavailable to microorganisms.