• Journal of Environmental Science International
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• v.6 no.6
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• pp.697-709
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• 1997

Sequencing Batch Reactor(SBR) experiments for organics and nutrients removal have been conducted to find an optimum anaerobic/anoxic/aerobic cycling time and evaluate the applicability of oxidation-reduction potential(ORP) as a process control parameter. In this study, a 61 bench-scale plant was used and fed with night-soil wastewater in K city which contained TCODcr : 10, 680 mg/l, TBm : 6, 893 mg/l, $NH_4^+-N$ : 1, 609 mg/l, $PO_4^{3-}-P$ : 602 mg/l on average. The cycling time In SBRs was adjusted at 12 hours and 24 hours, and then certainly included anaerobic, aerobic and inoxic conditions. Also, for each cycling time, we performed 3 series of experiment simultaneously which was set up 10 days, 20 days and 30 days as SRT From the experimental results, the optimum cycling time for biological nutrient removal with nlght-soil wastewater was respctively 3hrs, 5hrs, 3hrs(anaerobic-aerobic-anoxic), Nitrogen removal efficiency was 77.9%, 77.9%, 81.7% for each SRT, respectively. When external carbon source was fed in the anoxic phase, ORP-bending point indicating nitrate break point appeared clearly and nitrogen removal efficiency increased as 96.5%, 97.1%, 98.9%. Phosphate removal efficiency was 59.8%, 64.571, 68.6% for each SRT. Also, we finded the applicability of ORP as a process control parameter in SBRs.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.172-181
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• 2001

Upflow anaerobic sludge blanket (UASB) system employs granular sludge to treat various wastewaters including landfill leachate. CH$_4$ production of the granules determines overall performance of a UASB reactor. Sludge granules are developed by self-granulation of microorganisms and dynamic balance between granule growth and decay results in coexistence of granules with different sizes in the reactor. In this study, granules taken from a laboratory-scale UASB reactor were classified into 4 groups based on their diameters and their Physicochemical characteristics we were investigated. Each group was analyzed for settling ability, specific methanogenic activity (SMA), and elemental content. Settling ability was proportional to granule diameter. suggesting effective detainment of larger granules in the reactor. When acetate or glucose was used as a substrate, all groups showed relatively slight difference in SMA. However SMA with a volatile fatty acid mixture showed significant increase with granule diameter, suggesting better establishment of syntrophic relationship in larger granules. Larger granules showed higher value of SMA upon environmental changes (i.e., PH, temperature, or toxicant concentration). Comparative analysis of elemental contents showed that content (dry weight %) of most tested elements (iron, calcium, phosphorus, zinc, nickel. and manganese) deceased with granule diameter, suggesting importance of these elements for initial granulation. Taken together, this study verified experimentally that Physicochemical Properties of granules are related to granule size distributions. Overall results of physicochemical characterization supports that larger.

• Journal of Korea Soil Environment Society
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• v.2 no.3
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• pp.23-30
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• 1997

The purpose of this study was to evaluate effects of solids content and mixing speed in treatment of petroleum hydrocarbon contaminated soils using a slurry-phase bioreactor. Performance results on slurry-phase bioremediation of diesel fuel contaminated soil were generated at the bench-scale level. The fate of TPH(Total Petroleum Hydrocarbon) was evaluated in combination with biological treatment. Abiotic and biotic fate of the TPH were determined using soil not previously exposed to compounds in diesel fuel. The reactor volume for given throughput can be reduced by maximizing the solids content. Applications of 50% and 20% solids content(dry weight basis) were showed a little difference(57.5% : 61.6%) in biological TPH removal rate each other. Mixing and particle suspension are critical to desorption and biological degradation. In this standpoint, this study was performed using two mixing speed. When the reactor was operated at 70rpm, it had a better result in the particle suspension and TPH removal rate than the reactor with mixer rotated at 20rpm. In the reactor applied 20rpm, it was resulted in failure of particle suspension.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.235-238
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• 2002

Microorganisms were isolated from military shooting site. Aerobic batch reactor and resting cell condition experiments were carried out using isolated microorganisms. Experiments were examined at room temperature on shaker and ten-roll mixer. During 10 days of reaction time, TNT was degraded 15.51 ~ 22.47 mg/L from initial concentration(31$\pm$1 mg/L) by aerobic batch reactor. Aerobic resting cell condition experiments were carried out ill phosphate buffer with 58($\pm$1) mg/L TNT at pH of 6.0($\pm$0.2). TNT was degraded 67.8% of initial concentration. The mai or component was found 4-ADNT(4-Aminodinitrotoluene).

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.177-181
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• 2000

A lab-scale slurry reactor was developed for the treatment of contaminated sediments with polycyclic aromatic hydrocarbons (naphthalene, phenanthrene). In this system, range from 85 to 95% of PAHs with 2~3 rings were degraded within 11 days. Higher naphthalene degradation(94.05%) over phenanthrene degradation(87.07%) was probably due its higher solubility. Both compounds were not detected in aqueous phase after 7days and only 26.8% of naphthalene and 49.1% of phenanthrene were biodegraded. Removal TPH(Total Petroleum Hydrocarbon) concentration in solid after 11 days of treatment was 46%.

• Journal of Environmental Health Sciences
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• v.23 no.1
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• pp.1-7
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• 1997

We investigated the influence of various known sterilization methods on atrazine assimilation. The present study was designed to investigate the effect of autoclaving, sodium azide and mercuric chloride treatment on the assimilation of atrazine in soil and sediment. The sterilization reactor treated with sodium azide resulted in $^{14}CO_2$ generation and atrazine was rapidly disappeared from reactor through chemical reaction with sodium azide. These findings seem to indicate that sodium azide sterilization is not recommended for atrazine studies. In sample reactors autoclaved or treated with mercuric chloride, $^{14}CO_2$ generation was not detected and most of the disappeared atrazine was found to exist as hydroxyatrazine. These results suggested that autoclaving or mercuric chloride treatment could be effective sterilization methods. However, chemical properties(pH and redox potential) of soil and sediment were altered by any of the sterilization methods applied. So it was suspected that these altered properties could affect distribution and mineralization of atrazine in soil and sediment. In addition, both autoclaving and mercuric chloride treatment have altered $K_d$ values of hydroxyatrazine more significantly than those of atrazine. Consequently, although autoclaving and mercuric chloride treatment are effective sterilization methods, one must be careful in using them in practice as these methods may cause chemical degradation of both of atrazine and its metabolites and changes in chemical properties of soil and sediment. In conclusion, careful assessment of sterilization methods must be made for the degradation studies of chemicals in soil and sediment in order to minimize possible undesirable chemical degradation of sample and/or changes in physico-chemical properties of soil and sediment by the selected sterilization methods.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2974-2988
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• 2022

Implementation of component isolation in nuclear industry is challenging due to gaps in research and the lack of specific guidelines. In this study, parameters affecting component-level isolation of advanced reactor vessels are identified based on a representative numerical model with explicit consideration of nonlinear soil-structure interaction (SSI). The objective of this study is to evaluate the effectiveness of, and to identify potential limitations of using conventional friction pendulum bearings to seismically isolate vessels. It is found that slender vessels or components are particularly vulnerable to rotational accelerations at the isolation interface, which are caused by rotation of the sub-structure and by excitation of higher modes in the horizontal direction of the seismically isolated system. Component isolation is found to be more effective for relatively stiffer vessels and at sites with stiff soil. Considering that conventional isolators are deficient in resisting axial tension, it is observed that the optimum location for supporting a component to achieve seismic isolation, is at a cross-sectional plane passing through the center of mass of the vessel. These findings are corroborated by numerous simulations of the response of seismically isolated reactor vessels at different nuclear power plant sites subject to a variety of ground motions.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.5
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• pp.325-335
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• 2017

This study was carried out for 30 days in aeration type and agitation type reactor to characterize organic matter decomposition and ammonia volatilization during the liquid composting of pig slurry, and organic matter and nitrogen removal rate through mass balance analysis was analyzed. In the aeration type reactor, the pH increased from 7.0 to 9.13, and TS 34.5%, VS 33.4%, $BOD_5$ 71.2%, $COD_{Cr}$ 62.3% and TOC 83.2% were removed. In addition, 44.6% of TN and 65.0% of ${NH_4}^+-N$ were removed. In the agitation type reactor, the pH increased from 7.0 to 8.10, and the removal rates of TS 0.9%, VS 0.5%, $COD_{Cr}$ 27.5%, $BOD_5$ 28.9% and TOC 41.3% were obtained. And TN and ${NH_4}^+-N$ showed removal rate of 25.3% and 29.2%, respectively. The first order kinetics constant related to $BOD_5$ degradation was $-0.039day^{-1}$ for aerobic liquid composting and $-0.013day^{-1}$ for agitated reactor. Nitrogen loss in aerobic liquid composting was about 2.3 times higher than that of agitated reactor, whereas FAN/TAN in aerobic liquid composting was about 7.9 times higher than that of agitation type reactor. Therefore, despite the low FAN/TAN in the agitation type reactor, the nitrogen loss rate was relatively high.

• Journal of Soil and Groundwater Environment
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• v.27 no.3
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• pp.41-49
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• 2022

This study utilized citric acid as a floating agent in biological denitrification process and assessed its role under different carbon supplying conditions. Several microcosm tests including citric acid active (CAA), precipitating tablet release active (PTRA) and floating tablet release active (FTRA) were conducted to evaluate nitrate denitrification efficacy. In CAA reactors, nitrate removal was accompanied by the formation of denitrification by-products such as nitrite and nitrous oxide, with the extent of nitrate removal being proportional to citric acid concentration. These results suggest that citric acid induced heterotrophic biological denitrification. PTRA reactor that incorporated CAA and the same electron donor showed a similar denitrification efficiency to CAA reactor. FTRA reactor, which contained the same amount of fumarate as PTRA, enhanced denitrification by 7% as compared to the PTRA reactor. The overall results of this work indicate that surplus citric acid can be efficiently utilized in heterotrophic denitrification.

• Journal of Korea Soil Environment Society
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• v.3 no.3
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• pp.45-53
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• 1998

The purpose of this study was to evaluate effects of initial concentration and nutrients in treatment of petroleum hydrocarbon contaminated soils. The reactor used in this study was slurry-phase bioreactor of in-vessel type. Performance results on treatment of diesel fuel contaminated soils and micorbial growth were generated at the bench-scale level. The fate of TPH(Total Petroleum Hydrocarbon) and the microbial growth were evaluated in combination with biodegradation rate. Effect of initial loading levels of 50,000 and 100,000mg TPH/kg soil was studied. Performance results with two reactors were showed at the total TPH removal rate of 90.5% and 90.8%, respectively. However, the reactor with the initial concentration of 50,000mg TPH/kg soil showed higher biological TPH removal efficiency except for removal by volatilization than the other Although the different amount of nutrients was applied in two reactors, there was no remarkable difference in microbial growth rate. However, considerable factor in this results was that applied different initial concentration to two reactors. Although initial concentration was two times higher than it applied to the reactor without addition of nutrients, in total and biological TPH removal rate the reactor with addition of nutrients showed a higher than the other.