• Journal of Wetlands Research
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• v.19 no.2
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• pp.211-215
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• 2017

The market of the municipal wasetewater treatment plant (MWTP) operation is expanding across the world including Korea. The contracting-out system was introduced for the effective operation of MWTPs. However, an improvement of the contracting-out system of MWTP has been continuously required. This research investigated current operational status of MWTPs in Korea, to suggest the improvement of the cost effective MWTP operation to promote the contracting-out system of MWTP operation. Results showed that lower operational costs of MWTP were lower in larger MWTPs than in smaller MWTPs. Overall, MWTPs operated by a public enterprise showed lower operational costs than those operated by government agencies and private enterprises. Among the MWTPs similar in their treatment capacity, treatment process and operation period, MWTPs operated by private enterprises showed the lowest operational cost. According to the survey, managers and operators of MWTPs emphasized the importance of improvement on the methods of selecting operating agencies and estimating operationing costs. The results of this study should be useful as important supporting data to promote the contracting-out system for the MWTP operation.

• Journal of Wetlands Research
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• v.22 no.2
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• pp.92-99
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• 2020

Linked treatment refers to a system that relieves the burden of the business by linking high concentrations of wastewater such as human waste, manure, leachate, and other industrial wastewater to nearby municipal wastewater treatment plants(MWTPs). In 2018, 187 MWTPs, which are about 4.5% of the total domestic MWTPs, have implemented a linked treatment system, but local governments are having difficulties in operating sewage treatment due to lack of reasonable cost estimation standards. Therefore, we proposed an improvement plan to solve the problem in the calculation method that currently imposes linked wastewater. To this end, the effects and correlations of the linkage treatment system on the sewage treatment unit were analyzed, and among them, the main factors with the highest correlation were applied to the improvement plan. As a result, an improvement plan that improved three parts of the existing calculation method was presented, and the calculation method and the calculation case using the existing literature values were also presented. This can be used as a basis for future reference by local governments to implement linkage treatment, and to revise local sewerage ordinance and is believed to be helpful in operating a rational linkage system.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.237-243
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• 2011

As the effluent quality standard of the municipal wastewater treatment plant (MWTP) has been strengthened, the treatment of the recycle water containing high concentration of ammonium nitrogen has been considered as one of retrofit methods for upgrading the exising MWTPs. In this study, nitritation, economic nitrogen removal process, was induced by laboratory-scale reactor at the $35^{\circ}C$, $20^{\circ}C$, and $10^{\circ}C$ temperature conditions using anaerobic digester supernatant. The stable nitritation was achieved over $20^{\circ}C$, but nitrification was induced at $10^{\circ}C$. It means that the nitritation was affected by SRT and temperature. SRT, demanded for nitritation, is changed according to the temperature. Therefore, it is considered that SRT and temperature are important factors in nitritation. Also, it is approved that inducing the ammonium nitrogen removal and the nitritation are more beneficial over $20^{\circ}C$. The conclusion of this study can be used for the important basic reference when nitritation process is applied for MWTPs.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.3
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• pp.232-239
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• 2009

This research investigated the characteristics of antibiotic resistance of bacteria in microbial communities from municipal wastewater treatment plants (MWTPs), and monitored seasonal changes of antibiotic resistant bacteria (ARB) from MWTPs and Han river. When antibiotics were amended to either R2A agar (R2A) for general heterotrophs or MacConeky sorbitol agar (MSA) for coliform bacteria, all the MWTP samples exhibited multiple antibiotic resistance on the antibiotic-amended solid media. The antibiotic resistance appearing frequencies of ampicillin and sulfathiazole, respectively, were higher than reported data for other countries. The antibiotic resistance appearances differed depending upon the concentrations of primary substrate and nutrients and the types of cultivation media. The following 16S rRNA gene phylogenetic analysis showed that the identified multiple-antibiotic resistant microbes on R2A plates were more likely to be known human-pathogenic bacteria than the background heterotrophic bacteria were, suggesting a high risk of antibiotic resistance appearance to public health. In addition, according to our investigation of seasonal changes of ARB from urban MWTP and river samples, the frequency of ARB appearances was shown to correlate positively with temperature. This indicates a possibility that global warming result in increase in microbial risk to public health.

• Journal of Wetlands Research
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• v.17 no.3
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• pp.311-319
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• 2015

The Korean government has made progress in its project for sewage distribution in rural areas to ensure the balanced development of the country and its water conservation system. The project for sewage distribution in rural areas was analyzed with the yearly operational results of municipal wastewater treatment plant (MWTP). The sewage characteristics of the MWTP in a rural area changed according to seasonal variations, and the lowest pollution concentrations were obtained in the summer. The treatment efficiency of nutrients in the biological treatment process changed slightly more than the treatment efficiency of organic compounds, and the lowest treatment efficiency was obtained in winter. In addition, the relationship between treatment efficiency and retention time and F/M ratio showed similar results despite seasonal variations. It was considered that sewage characteristics and treatment efficiency changed according to seasonal variations when the treatment process was selected in MWTPs in rural areas. Especially, Maintenance of MWPT is need for the stable treatment efficiency of nutrients in the winter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5052-5059
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• 2012

This study was carried out to find consumers' attributes and willingness to pay(WTP) of agricultural products cultivated from plants factory system. The agricultural products were sorted into lettuce, strawberry, Ligularia fischeri(wild edible greens), and ginseng. We made the questionaires to survey consumers' purchasing attributes and preference of agricultural products. Finally, 200 valid replies were selected to analyze consumers' attributes and to estimate marginal willingness to pay. We used conjoint analysis and multinomial logit model for empirical analysis. MWTPs of commodities are estimated as follows; Lettuce is 1,016KW(100g), Strawberry is 6,014KW(2kg), Ligularia fischeri is 3,652KW(100g), and Ginseng is 5,905KW(100g). Several attributes of consumers' purchasing behavior were identified from this study. We suggested several implications to formulate more appropriate policy of plants factory system.

• Journal of Wetlands Research
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• v.19 no.4
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• pp.501-507
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• 2017

The heavy metal such as Nikel (Ni) in industrial wastewater is one of the major reasons of decreasing nitrification efficiency in municipal wastewater treatment plants (MWTPs). In this study, laboratory scale reactors were operated in order to analyse of nitrification efficiency and improvement measures. As a result, nitrification efficiency during high Ni concentration (0.295 mg/L) was about 20%. However nitrification efficiency during low Ni concentration (0.114 mg/L) was over 70%. The changes of the micro-organism activity according to Ni concentration was investigated as being the major reason behind the gap of nitrification efficiency through analysing AUR and SNR. Increasing the HRT in high Ni concentration also increased the nitrification efficiency. Thus, maintenance of microorganisms and increasing the HRT in nitrification reactors suggests that measures taken to treat wastewater is positively correlated with high concentration of heavy metal.

• Journal of Wetlands Research
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• v.22 no.2
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• pp.139-144
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• 2020

Recently, high-concentration linked wastewater has been introduced into a nearby municipal wastewater treatment plants(MWTPs), but it is difficult to MWTP in local governments due to an unreasonable linked treatment charge system, and there is insufficient evidence or data to prove this. However, the MWTP, which is a national essential infrastructure, is generally exempt from the preliminary feasibility study, so there have been no cases where economic evaluation was conducted. Therefore, we proposed an improvement plan that can compensate for the disadvantages of the existing linked processing charges through previous studies. In this study, a comparative evaluation of how much economic feasibility can be improved compared to the existing ones when applying the improvement plan by conducting an economic analysis. For this, reference was made to the preliminary feasibility assessment data of the existing environmental facilities and the cost factors and benefit factors established during the modernization of the old sewage treatment facilities. As a result of the study, the B/C(Benefit/cost) value was quite low in the past, but when the improvement proposal proposed by the researchers was applied, it was confirmed that the B/C value increased close to 1. Therefore, it is considered to be very reasonable to calculate the linkage processing charge according to the linked wastewater load proposed by the researchers.

• Journal of Wetlands Research
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• v.20 no.4
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• pp.390-397
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• 2018

The Municipal Wastewater Treatment Plant(MWTP), located industrial estate, has a problem of decreasing nitrification efficiency. In this research, it was analyzed that effect of heavy metals and retention time to nitrification based on operational result of laboratory scale reactors. And suggest improving MWTP operation method for increasing nitrification efficiency based on findings. According to operational result, laboratory scale reactor shows over 60% nitrification efficiency over hydraulic retention time(HRT) 0.5 day. However, the nitrification efficiency of S MWTP(high heavy metal concentration) sample was lower than that of A MWTP(low heavy metal concentration) sample in same operational condition. The main reason was heavy metals in industrial wastewater. This heavy metals was acted as inhibitor to nitrifier in reactors. So, activity of nitrifier was analyzed based on specific nitrification rate(SNR). The SNR of S MWTP sample shows 0.13 ~ 0.21 mg NH4/gMLSS/hr and that of A MWTP sample shows 0.74 mg NH4/gMLSS/hr. As a result, the activity of nitrifier of S MWTP was lower than that of A MWPT. In other words, retrofit methods for improving nitrification efficiency in MWTPs located industrial estate were that to increase retention time in biological treatment process or to pretreat heavy metal before being injected biological treatment process.

• Journal of Wetlands Research
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• v.24 no.1
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• pp.38-43
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• 2022

Smart sewage treatment plant means creating a safe and clean water environment by establishing an ICT-based real-time monitoring, remote control management and intelligent system for the entire sewage treatment process. The core technology of such a smart sewage treatment plant can be operation control technology using measuring instruments. This research team analyzed and suggested the operation control technologies necessary for the establishment of the intelligent business by referring to the intelligent research projects of the sewage treatment plant in progress in Korea. As a result of the analysis, a total of six removal technologies were presented, including control by scale, reflow water control, linked treated water control, chemical quantity control, winter operation control, and total organic carbon control. By size, standards that can be classified into small and medium-sized large-scale are presented, and in the case of reflow water control, the location of water quality and flow sensors capable of managing reflow water is suggested. In the case of the linked treated water control, the influence and control points of the linked treated water on the sewage treatment plant were presented, and in the case of the chemical injection volume control, a system capable of optimizing the amount of chemical injection according to the introduction of an intelligent sewage treatment plant was presented. In the case of winter operation, the sensors and pumps to be controlled are suggested when considering the decrease in nitrification due to the decrease in water temperature. In the case of total organic carbon control, an interlocking system considering the total amount of pollution in the future was proposed. These operation control scenarios are expected to be used as basic data to be used in intelligent sewage treatment algorithms and scenarios in the future.