• KSBB Journal
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• v.22 no.3
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• pp.157-161
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• 2007

This study is to investigate the biological degradation and the characteristics of MEA, a pH regulator to be put in the cooling water circulation system for power plants, loading to elevate concentrations of COD and N when eluted into the water environment. MEA, $NH_4^+$ and CODcr were monitored in flask cultures and in a batch aerator. MEA was found to be biologically degradable, producing substantial amount of ammonia (max. 78.1%) in a form of $NH_4^+$ and other carboneous intermediates. The degradation reaction rates were similar one another over all MEA concentrations tested as the activated sludge (microbial consortium) was acclimated to MEA with the gradual and stepwise increase in MEA input into the batch aerator. Also, MLVSS kept increasing with increasing MEA input. The COD-based degradation reaction order was determined to be 1.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.669-678
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• 2014

The amount of waste water generated from the domestic sources is consistently increasing in proportion to economic growth, and the conventional activated sludge process is widely being used for general waste water treatment. But the ministry of environment becomes stringthent treatment standards of N and P (less than 20mg/L of N, 2mg/L of P) to prevent the eutrophication of lake water, and therefore highly advanced treatment technology is required not only in the existing treatment plants where the activated sludge process is being used, but also in newly constructed treatment plants for the treatment of N and P. This study is aimed at highly operating the engineering technology method was developed by domestic to eliminate N and P at the same time. Experiments were conducted in the treatment plant located in Yong In city. The bioreactor was started from the principal equipment for the elimination of N and P and the elimination of organic compounds. It consists of an internal recycle piping from the end of the aerobic tank to the anoxic tank and external recycle piping from the final settling basin to the denitrification tank. By experiment of 4 types separate inflow of waste water to the denitrification tank and the anaerobic tank, and changes in staying time at the anoxic tank and the aerobic tank, the elimination of organic compounds in each type and the relationship in the efficiency between the elimination of N and P were researched.

• Applied Biological Chemistry
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• v.35 no.4
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• pp.242-247
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• 1992

Twenty strains of pentachlorophnol (PCP) resistant bacteria were isolated from activated sludge of the sewage treatment plant of Jung Lang Chun, Seoul. The predominant strains were Bacillus spp. including B. sphaericus and E. schlegelii. The other strains were identified as Corynebacterium spp., Staphylococcus aureus, Arthrobacter spp. and Aeromonas spp. The resistant strains could be grouped into two categories; PCP-degrading and PCP-adsorbing/absorbing ones. PCP-degrading strains degraded $75{\sim}90%$ of PCP in the medium containing 100 ppm PCP during the first 24 hours of growth. At the initial period the PCP-adsorbing/absorbing strains removed PCP from the medium but started to release PCP after 24 or 72 hours of growth. PCP degradation products from the culture broth of PCP-degrading strains were identified by comparing their $R_f$ values with those of the reference compounds. 2-chlorophenol and 2.4-dichlorophenol were presumed to be the intermediate products of PCP degradation.

• Journal of Korean Society on Water Environment
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• v.20 no.5
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• pp.457-465
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• 2004

The objective of this study is to evaluate the possibility to apply the Moving Bed Biofilm Reactor(MBBR) in the activated sludge treatment process with existing aerobic HRT. Optimal operation conditions were assumed according to the analysis of organic matter and nutrients removal efficiencies depending on loading variations. The process was operated under different conditions: RUN I(HRT=7.14hr, $I{\cdot}R=100%$), RUN II(HRT=6.22hr, $I{\cdot}R=100%$), RUN III(HRT=6.22 hr, $I{\cdot}R=150%$), RUN IV(HRT=6.22hr, $I{\cdot}R=200%$), the TBOD removal efficien cies are 88%, 88.5%, 94.6%, 97.6%, respectively. Overall TSS removal efficiency is 90%, and it is increasing in RUN IV. In the case of Nitrogen, the highest removal efficiency of 90% was observed in RUN III and RUN IV, Nitrification and Denitrification rates are 0.013-0.016kg $NH_3-N/kg$ Mv-d and 0.009-0.019kg $NO_3/kg$ Mv-d, respectively. Phosphorus removal efficiencies are 89.6% in RUN I, 91.5% in RUN II, 84.3% in RUN III, and 76.4% in RUN IV. The process under shorter SRT yields better performance in terms of phosphorus removal. It was noticed that to achieve the effluent phosphorus concentration ofless than 1mg/L and removal efficiency higher than 80%, SRT should not be longer than 10 days. Experimental result shows that HRT of 6.22 hours is suitable for this treatment process, and, as a result, the aerobic reactor including moving media and DO depletion tank have a sufficient effect to the process performance.

• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.81-88
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• 2010

This study was conducted to find the capability of comparison of overall oxygen transfer coefficient in the membrane coupled high performance reactor (MPHCR) in treating high organic loading wastewater. Effluent quality had been analyzed while the influent organic loading rate was changed from 2 to $7kg\;COD/m^3{\cdot}day$. The oxygen transfer coefficients had been investigated using two-phase nozzle for operating variables which were internal circulation flowrate (5~8 L/min), air flow rate (0.0125~0.2 L/min), liquid temperature ($10{\sim}20^{\circ}C$), and pure-oxygen flow rate (0.0125~0.2 L/min). The overall oxygen transfer coefficient was increased with flowrate of internal circulation and air and high temperature. Especially, internal circulation flow rate showed distinct effect on overall oxygen transfer coefficient due to an increase of gas holdup and air-liquid contract area by two-phase nozzle. In the high range of organic loading rate from 4 to $7kg\;COD/m^3{\cdot}day$, the removable efficiency of COD was 91%. Conventional activated sludge process usually treat organic loading from 0.32 to $0.64kg\;COD/m^3{\cdot}day$ however, the MPHCR can treat 10 to 20 times higher if it would be compared to the conventional activated sludge process. Foaming problem often happened and caused biomass wash out of the reactor, therefore, the foaming should be controlled for the enhanced operation.

• Journal of Wetlands Research
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• v.16 no.3
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• pp.347-353
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• 2014

This work was performed to find the effect of operation parameters on the permeate flux through the activated sludge dynamic layer, and to indicate the relationship between the water quality of supernatant and flux based on the results. Since the effluent can be obtained through steady and stable formation of cake layer in the bio-filter media system, it is an important subject to keep and control microbes with activated state in the bio-reactor. Filtration resistance was drastically increased at more than 18000mg/L of MLSS. With filtration time continued, the flux was gradually decreased and the water qualities of supernatant monitored by turbidity and TOC were also deteriorated. This phenomenon indicated that the organic materials generated by microbes and accumulated in the reactor might affect the flux in the system. In addition, the decrease of flux was simultaneously observed in the sludge volume index. When SVI was controlled from 150 to 250, the flux was also decreased. The proper aeration time was recommended to 30 to 60 seconds in this system. In order to operate this system steadily, therefore, the control of water quality of supernatant and SVI should be proceeded.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.3
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• pp.119-126
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• 2001

A process for the production of bioplastics from wastewater with an open microbial culture was developed and evaluated. The process consists of a selection reactor to select bacteria in feast/famine regime and an accumulation reactor to produce PHA using selected bacteria. Polyhydroxyalkanoate(PHAs) accumulating bacteria could be efficiently grown in a sequencing batch reactor(SBR) without any growth limitation. For the high production of PHA limitation such as oxygen and nutrients seemed to be needed. Accumulation experiments were performed to evaluate the level of accumulation of PHA. Limited aeration had no effect, but nutrients limitation showed high accumulation. Bacteria which were selected in the SBR could accumulate PHA till 60% of cellular dry weight in accumulation experiments under nitrogen limitation. PHA accumulation rate decreased with increasing PHA content in the cells. Clearly, PHA accumulation rate has a strong correlation with the PHA content of the cells.

• Journal of Microbiology and Biotechnology
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• v.12 no.4
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• pp.569-575
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• 2002

Two bacterial strains capable of degrading trichloroethylene (TCE), isolated form soils contaminated with various chlorinated alkenes, were identified as Alcaligenes odorous N6 and Nocardia sp. Hl7. In addition, four KCTC strains, including three strains of Pseudomonas putida and one strain of Sphingomonas chlorophenolica, exhibited an ability to degrade toluene. A. odorans N6 and Nocardia sp. H17 degraded 84% of the initial amount of TCE in a basal salts medium (BSM), containing 0.2 mM TCE as the sole source of carbon and energy, in a day. The optimal pH for growth was within a range of 7.0-8.0. A mixed culture of the four toluene-degrading isolates degraded 95% of 0.2 mM TCE with 1.5 mM toluene as an inducer, whereas no TCE was degraded by the same mixture without an inducer. When a mixed culture of all 6 isolates was used, the degradation efficiency of 0.2 mM TCE was 72% without an inducer, in a day, and 82% with toluene as an inducer. In a continuous treatment, 1,000 mg/1 of TCE in an artificial wastewater was completely removed within 18 h when an activated sludge was used along with the microbial mixture, which was 27 h laster than when only an activated sludge was used. Accordingly, it would appear that such a microbial mixture could be effectively applied to the biological treatment of wastewater containing TCE with or without an inducer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.21-25
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• 2002

Activated sludge processes are widely used in biological wastewater treatment processes. The main motivation of this research is to develop an intelligent control strategy for activated sludge process (ASP). ASP is a complex and nonlinear dynamic system because of the characteristic of wastewater, the change in influent rate, weather conditions, and so on. The mathematical model of ASP also includes uncertainties which are ignored or not considered by process engineer or controller designer. The ASP model based on Matlab/Simulink is designed in this paper. The performance of the model is tested by IWA (International Water Association) and COST (European Cooperation in the filed of Scientific and Technical Research) data that include steady-state results during 14 days. In this paper, fuzzy logic control approach is applied to control the DO (dissolved oxygen) concentration. The fuzzy logic controller that includes two inputs and one output can adjust air flowrate. Also, this paper introduces the remote monitoring and control system that is applied for the CSTR (Continuously Stirred Tank Reactor) wastewater treatment system. The CSTR plant has a local control and the remote monitoring system which is contained communication parts which consist of LAN (Local Area Network) network and CDMA (Code Division Multiple Access) wireless module. Remote control and monitoring systems are constructed in the laboratory.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.534-539
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• 2006

The supply of oxygen for aeration is the largest energy consumer at activated sludge wastewater treatment plants. Replacement of less efficient aeration systems with fine pore aeration devices can save up to 50 percent of aeration energy costs. The purpose of this study was the diagnosis and evaluation of a domestic wastewater aeration system by the off-gas method which had been studied by US EPA and ASCE. For this study, an off-gas analyzer and its hood were made to collect off-gas. Also, a vacuum pump was connected to the analyzer to make suction of off-gas. Experiments were conducted at a domestic activated sludge wastewater treatment plant which had a single spiral roll aeration system installed with P.E tube diffuser. Data on OTE(f), SOTE(pw), OUR, and air flow rate were obtained from these experiments. In case of replacing an aeration system, it is recommended that it should be replaced with perforated membrane disc or ceramic disc fine bubble diffusers installed in a full floor coverage or grid pattern.