• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.739-745
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• 2005

Simultaneous denitrification and methanogenesis at various influent COD/Nitrate-N(below C/N) ratio was investigated with two different anaerobic sludges of which one was inoculated with glucose only and the other was inoculated with glucose and nitrate. Three different C/N ratios of 30, 20, and 10 were applied with each anaerobic sludge in serum bottles agitated in a rotary shaker to monitor the time related changes of amount of gas production and gas composition. Glucose was used as a single carbon source, which was adjusted to 1,000 mg/L as COD and potassium nitrate was used as a nitrogen source to adjust the each C/N ratio. COD removal by methanogenesis was dominant at higher C/N ratios, while COD removal by denitrification was dominant at lower C/N ratios. With the sludges cultured at C/N ratios below 10, SMA and SDNR rising different carbon substrates were investigated. The most efficient carbon substrate was acetate and the highest SMA and SDNR were 0.76 g COD/g VSS day with pure anaerobic sludge and 1.38 g ${NO_3}^--N/g$ VSS day with sludge cultured at C/N ratio of 5, respectively.

• Korean Journal of Microbiology
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• v.55 no.3
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• pp.242-247
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• 2019

Biological factors (e.g. microorganism activity) in wastewater treatment plant (WWTP) play essential roles for degradation and/or removal of organic matters. In this study, to understand the microbial functional roles in WWTP, we tried to isolate and characterize a bacterial strain from activated sludge sample. Strain S16 was isolated from the activated sludge of a municipal WWTP in Daejeon metropolitan city, the Republic of Korea. The cells were a Gram-stain-positive, non-motile, facultative anaerobe, and rod-shaped. Strain S16 grew at a temperature of $15{\sim}40^{\circ}C$ (optimum, $30^{\circ}C$), with 0~9.0% (w/v) NaCl (optimum, 1.0~2.0%), and at pH 5.5~9.0 (optimum, pH 7.0~7.5). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain S16 was most closely related to the unique species Miniimonas arenae NBRC $106267^T$ (99.79%, 16S rRNA gene sequence similarity) of the genus Miniimonas. The cell wall contained alanine, glutamic acid, serine, and ornithine. Although the isolation source of the type strain NBRC $106267^T$ which considered as a marine microorganism is sea sand, that of strain S16 is terrestrial environment. It might raise an ecological question for habitat transition. Therefore, comparative genome analysis will be valuable investigation for shedding light on their potential metabolic traits and genomic streamlining.

• Journal of Microbiology and Biotechnology
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• v.21 no.1
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• pp.37-42
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• 2011

A new versatile acrylonitrile-bioconverting strain isolated from a petroleum-contaminated sludge sample and identified as Rhodococcus ruber AKSH-84 was used for optimization of medium and biotransformation conditions for nitrilase activity to produce acrylic acid. A simple and rapid HPLC protocol was optimized for quantification of acrylic acid, acrylamide, and acrylonitrile. The optimal medium conditions for nitrilase activity were pH of 7.0, temperature of $30^{\circ}C$, agitation of 150 rpm, and inoculum level of 2%. Glycerol as a carbon source and sodium nitrate as the nitrogen source provided good nutritional sources for achieving good biotransformation. Nitrilase activity was constitutive in nature and was in the exponential growth phase after 24 h of incubation under optimal conditions without addition of any inducer. The substrate preference was acrylonitrile and acetonitrile. The present work demonstrates the biotransformation of acrylonitrile to acrylic acid with the new strain, R. ruber AKSH-84, which can be used in green biosynthesis of acrylic acid for biotechnological processes. The nitrilase produced by the isolate was purified and characterized.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.120-124
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• 2009

This study was performed to investigate the application of submerged membrane bioreactor (MBR) system for biological nutrient removal of municipal wastewater. MBR bioreactor consists of four reactors such as anaerobic, stabilization, anoxic and submerged membrane aerobic reactors with two internal recycles. The hydraulic retention time (HRT), sludge retention time (SRT) and flux were 6.2 hr, 34.1 days and $19.6L/m^2/hr$ (LMH), respectively. As a result of operation, the removal efficiency of $COD_{Cr}$, SS, TN and TP were 94.3%, 99.9%, 69.4%, and 74.6%, respectively. There was no significant effect of microbial activity after the maintenance cleaning using 200 mg/L of NaOCl. Membrane filtration for the treatment of municipal wastewater was performed for longer than 9 months without chemical recovery cleaning.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.981-987
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• 2000

Upflow anaerobic sludge blanket(UASB) reactor was operated for treating swine wastewater containing high ammonia nitrogen to assess their performance and toxicity of free ammonia concentration. In the reactor, chemical oxygen demand(COD) removed about 70% at $2.6kgCOD/m^3.day$ of organic loading rate(OLR) and 3 days of hydraulic retention time (HRT), while it was decreased when OLR and HRT was maintained $7kg\;COD/m^3.day$ and 2 days, respectively. Also UASB reactor was evaluated the activity of methane producing bacteria(MPB) according to change of free ammonia concentrations, MPB activity of applied sludge in the 500 and $1000mg-N/{\ell}$ of free ammonia concentration was inhibited by 4% and 40%, respectively. This clearly showed that free ammonia concentration less than $500mg-N/{\ell}$ showed no inhibition to MPB in anaerobic treatment of organics, UASB reactor was stabilized easily less than $1000mgVSS/{\ell}$ due to degradation of organic solids by the high activities of anaerobes.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.7
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• pp.771-777
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• 2007

Several endocrine disrupting chemicals(EDCs) were monitored to evaluate the estrogenic activities and the concentrations by yeast two-hybrid assay and enzyme-linked immunosorbent assay(ELISA) in sewage treatment plant(STP) which consist of industrial and domestic line. In the influent of domestic line, estrone, 17$\beta$-estradiol, 17$\alpha$-ethinylestradiol and alkylphenolethoxylate(APE) were detected up to 167.1, 39.7, 7.3 and 145.4 ng/L, respectively. The average removal efficiency of 17$\beta$-estradiol after the activated sludge process was 77.5% and further removed to 80.8% after the sand filtration-ozonation step. These results suggests that the activated sludge process has limited potential to remove the estrogenic activity effectively. The contributions of the estrogenic chemicals to the estrogenic activities were 70.7, 23.3, 3.7 and 2.3% for estrone, 17$\beta$-estradiol 17$\alpha$-ethinylestradiol and APE, respectively, in the domestic line effluents. Therefore, 17$\beta$-estradiol and estrone contributed most of the estrogenic activity in the domestic line effluents.

• Journal of the Korea Organic Resources Recycling Association
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• v.3 no.2
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• pp.79-89
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• 1995

Changes of microbial activity and physicochemical environment during composting of papermill sludge(PMS) in the pilot plant equipped with an agitated bed reactor were monitored for establishing the efficient composting system. Microbial activity determined as the evolution of $CO_2$ increased for the first 10 days after introduction of PMS to the reactor and decreased thereafter. Population changes of microorganisms in the reactor-PMS were not typical as in windrow system. The ratio of thermophilic bacteria to mesophilic bacteria, however, increased slowly even 23 days after introduction. Temperature of PMS increased rapidly from the first day and reached $62^{\circ}C$ at 7 days after introduction and decreased slowly thereafter. The acidity of PMS was pH 6.8 initially, increased to pH 8.0 after 7 days and decreased to pH 7.4 after 23 days. Redox potential(Eh) of PMS was -320mV at the beginning of composting, but it was increased with time to reach -15mV after 23 days composting. However, Eh of PMS pre-sterilized before measurement was average 50mV, regardless of composting periods indicating the major role of microorganisms during composting process. Water content of PMS was 67% initially and decreased to about 50% after 23 days composting in the reactor. Less than 13 days-old compost inhibited growth of radish in the container mixture with bed soil. Based on statistical analysis of microbial and physicochemical parameters of PMS during composting, an equation was developed for determining compost maturity. A number of experiments using various organic wastes are required before application of the formular to the practical use.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.2
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• pp.146-152
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• 2015

Heavy metal pollution has been a critical problem in agricultural field near at the abandoned metal mines and chemical amendments are applied for remediation purpose. However, biological activity can be changed depending on chemical amendments affecting crop productivity. Main purpose of this research was to evaluate biological parameters after applying chemical amendments in heavy metal polluted agricultural field. Result showed that soil respiration (SR) and microbial biomass carbon (MBC) were changed after chemical amendments were applied. Among three different amendments, lime stone (LS), steel slag (SS), and acid mine drainage sludge(AMDS), AMDS had an effect to increase SR in paddy soil. Comparing to control ($93.98-170.33mg\;kg^{-1}day^{-1}$), average of 30% increased SR was observed. In terms of MBC, SS had an increased effect in paddy soil. However, no significant difference of SR and MBC was observed in upland soil after chemical amendment application. Overall, SR can be used as an indicator of heavy metal remediation in paddy soil.

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.235-240
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• 2002

Protease producing bacterium, PB16 was isolated from food processing wastewater sludge and paddy field soil samples and selected by the clear zone and enzyme activity test. The isolate was gram negative, rod type and its protease productivity was 6.49 U/ml. As a result of API20NE kit test and 16S rDNA sequencying, the isolated PB16 was identified as Aeromonas hydrophila (99%). The growth rate ($h^{-1}$) was 0.21 in synthetic waste water only and 0.26 in synthetic waste water containing vitamin and mineral using a bioscreen C. Synthetic wastewater removal rate was 59 and 87%, respectively after 1 and 3 day reaction (intial CODcr was 2,472 mg/l).

• Journal of the Korean Applied Science and Technology
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• v.25 no.2
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• pp.168-174
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• 2008

This study is focused on the antimicrobial activity of cyanobacteria Microcystis aeruginosa by the reduction and oxidation reaction of copper and zinc alloy metal fiber filter. Cu/Zn ion is easily makes radicals with molecular hydroperoxide. Especially, hydroperoxide radical shows strong toxicity to the strains. Plasma membrane causes conformational change when hydroperoxide radical binds to plasma membrane. Elution of copper ion from copper and zinc alloy metal fiber is detected in the cyanobacteria solution as 0.5 ppm, and that of zinc ion is 0 ppm respectively. Zinc ion is figured to form a hydroxide in the cyanobacteria solution and precipitated to form a sludge. The concentration of chlorophyll-a in the cyanobacteria solution was proved to be the index of antimicrobial level of Microcystis aeruginosa.