• Nuclear Engineering and Technology
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• v.50 no.8
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• pp.1355-1363
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• 2018

Many radionuclides exist in normal environment and artificial radionuclides also can be detected. The radionuclides ($^{131}I$) are widely used for labeling compounds and radiation therapy. In Korea, the radionuclide ($^{131}I$) is produced at the Radioisotope Production Facility (RIPF) at the Korea Atomic Energy Research Institute in Daejeon. The residents around the RIPF assume that $^{131}I$ detected in environmental samples is produced from RIPF. To ensure the safety of the residents, the radioactive concentration of $^{131}I$ near the RIPF was investigated by monitoring environmental samples along the Gap River. The selected geographical places are near the nuclear installation, another possible location for $^{131}I$ detection, and downstream of the Gap River. The first selected places are the "front gate of KAERI", and the "Donghwa bridge". The second selected place is the sewage treatment plant. Therefore, the Wonchon bridge is selected for the upstream of the plant and the sewage treatment plant is selected for the downstream of the plant. The last selected places are the downstream where the two paths converged, which is Yongshin bridge (in front of the cogeneration plant). In these places, environmental samples, including sediment, fish, surface water, and aquatic plants, were collected. In this study, the radioactive iodine ($^{131}I$) detection along the Gap River will be investigated.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.337-341
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• 2005

It is difficult to use average sewage water quality as a design parameter for the individual sewage wastewater treatment plant(ISWTP), because sewage water quality is very various according to the building use type. So, in this study, we estimated daily, seasonal and weekly trend of sewage water quality and flow rate in various kind of building to comprehend operating state of ISWTP. The sewage water quality and flow rate were higher in the business building than household building. The seasonal difference of the water quality was not detected but that of flow rate was high. The flow rate of the sewage in the business building was higher in summer than in other seasons and in weekend than in weekday. The treatment efficiency of IWSTP was about $70{\sim}80%$ with BOD, $40{\sim}50%$ with TN and TP, which was very low. The unit loads of the individual house were 36.05 gpcd with BOD, 37.91 gpcd with SS, 23.91 gpcd with T-N, and 7.90 gpcd with T-P respectively, and those values were higher than other studies. It is because, as distinct from other studies, sewage water quality was monitored at the inlet point of the IWSTP in this study. We can use this results as an one of basic parameters for the design of IWSTP.

• Journal of Wetlands Research
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• v.23 no.1
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• pp.7-13
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• 2021

Due to rapid industrial development, population growth, and improvement of living standards, the amount of sewage and wastewater, including nutrients, is increasing every year. In addition to the increasing amount of sewage and wastewater generation, untreated linked treated water (manure, livestock manure, industrial wastewater, leachate, food waste) is also increasing, and many of the linked treated water flows directly into nearby sewage treatment plants. The associated treated water causes many problems because of its own characteristics, low flow rate with high concentration compared to existing inflow sewage. In order to solve this problem, it is necessary to investigate the quantity and quality of the connected treated water whichh is flowed into the sewage treatment plant, and a study the effect on sewage treatment. Therefore, in this paper, we would like to examine the effect of the linked treated water. Seasonal effect associated with water pollution conditions was considered. In addition, a scenario was created through the distribution and inflow of connected treated water along with the water temperature conditions. Through scenario analysis, we intend to optimize the operating conditions of linked processing.

• Journal of Wetlands Research
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• v.21 no.2
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• pp.147-151
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• 2019

Recently, rural areas are rapidly developing, while existing infrastructure is inadequate and aging compared to developing rural areas. The most representative of these is the sewer system. Therefore, in this study, the rural area of Gyeonggi A city was selected as the study area and analyzed the effect of the sewer maintenance business on the operation of the sewage treatment plant. The analysis items were pollutant treatment efficiencies, the changes of inflow sewage amount, sewage concentration, influnet load, and C / N ratio by comparing before and after the development. As a result of the analysis, the sewage amount increased significantly after the development, and the sewage concentration increased after the development and the load of the sewage in the wastewater treatment plant also increased after the development. And improvement and management of inflow of unidentified water such as infiltration water and influent water in the sewage pipe was improved due to improvement of sewage pipe, which is considered to have affected the increase of C / N ratio and the improvement of TN and TP removal efficiency. The results of this study can be used as a representative example of the sewerage maintenance project in the rural area that positively influenced the operation of the sewage.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.619-628
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• 2017

As the 3D laser scanning technology capable of databaseing large sewage box culverts becomes possible, it is necessary to develop a standardization manual that can clearly distinguish the structural and operational defect types of box culver and analyze the defect data. In this study, we collected and analyzed defects in sewage box culverts of 14,827m in total by selecting three districts in Korea. The major defects were surface damages, and their defect densities were $2.17m^2/m$, $0.27m^2/m$ and $0.10m^2/m$ for aggregate exposure, Steel reinforcement exposure, and Steel reinforcement projecting. In order to support the decision of the box culverment management, it was divided into five grades and each defect code and defect score were allocated. The results of this study are useful for the diagnosis of the sewage box culverts in Korea and it is expected to support a decision making for management.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.1
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• pp.10-19
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• 1999

In 1991, the ministry of Gov't. Administration and Home Affairs set up a minimum of one sewage disposal plant in each province. By 1995, 264 models of the capillary infiltration method were set up in 331(78%) villages and the contact oxidation method was set up in 52 places. Since the Gov't. sent a letter to each responsible officer across the country stating their disapproval of the capillary infiltration method, the environmentally friendly sewage disposal system has not been diffused. The current model(mechanical sewage disposal) being used, in agricultural and fishing villages, costs too much for maintenance and operation(\50,000 per capita per year). In particular, because of the difference in sewage characteristics of agricultural and fishing villages from urban sewage, the efficiency of the disposal system is very low. Also, because of the growing need for more disposal plants, the Gov't. is looking for cheaper alternatives. This study has analyzed 2 kinds of sewage disposal. The first is used widely in agricultural and fishing villages in Germany. The second is used widely in similar areas of Korea. It has intended to analyze the characteristics, merits and defects of the sewage disposal water plants and pebbles model which is used widely in Germany and developed compatibly for Korea.

• Environmental Engineering Research
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• v.19 no.1
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• pp.59-66
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• 2014

The aim of this study was to assess the effect of pre-aeration on sludge solubilization and the behaviors of nitrogen, dissolved sulfide, sulfate, and siloxane. The results of this study showed that soluble chemical oxygen demand in sewage sludge could be increased through pre-aeration. The pre-aeration process resulted in a higher methane yield compared to the anaerobic condition (blank). The pre-aeration of sewage sludge, therefore, was shown to be an effective method for enhancing the digestibility of the sewage sludge. In addition, this result confirms that the pre-aeration of sewage sludge prior to its anaerobic digestion accelerates the growth of methanogenic bacteria. Removal rates for $NH_3$-N and T-N increased simultaneously during pre-aeration, indicating simultaneous nitrification and denitrification. The siloxane concentration in sewage sludge decreased by 40% after 96 hr of pre-aeration; in contrast, the sulfide concentration in sewage sludge did not change. Therefore, pre-aeration can be employed as an efficient treatment option to achieve higher methane yield and lower siloxane concentration in sewage sludge. In addition, reduction of nitrogen loading by pre-aeration can reduce operating costs to achieve better effluent water quality in wastewater treatment plant and benefit the anaerobic process by minimizing the toxic effect of ammonia.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.11
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• pp.763-768
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• 2013

The simulation investigation on the availability with failure density function of major equipment for a sewage treatment plant has been carried out. This study focuses on the availability of the plant and criticality with equipment module induced by component layout and its failure function. The equipment classification of sewage treatment plant and its failure function are established. Also solution methodologies are introduced as Monte-Carlo simulation method and event algorithm for uncertainty problem. The availability in the case of serial connection of equipment with all exponential function is calculated as around 50.4%. In other case of parallel combination with back up equipment, the availability showed over 80.1%. The criticality that a ffects availability showed high value over 77% in the dehydration and concentration process of sludge.

• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.778-784
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• 2009

The purpose of this study is to figure out the differences of the inflow rates of Sewage Treatment Plants (STP), invested by public fund or public-private partnership (PPP). This paper finds that the average ratio of sewage inflow according to facility capacities (medium and small scale STP) was either nearly below 30% or above 100% in the first year. As the size of STP increased, there was decrease in the accuracy of demand assumption. This was because the operation time when the ratio of sewage inflow was uniform was different according to the size of STP, whereby the time was short when the STP were small. The design average ratio of sewage inflow was 10% larger than the real average ratio; this was considered overdesigned. In the case of a plant built by the PPP scheme, the average ratio of inflow of the STP before an abolition of MRG was larger than after the abolition of MRG. This may be explained by moral hazard from too much reliance on MRG. After the abolition of MRG, the demand risk of PPP was shifted from a PPP project to a conventional project.

• Korean Journal of Environmental Agriculture
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• v.25 no.3
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• pp.247-256
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• 2006

This study has been conducted for the process of food wastes disposal using surplus capacity of established sewage treatment plant by co-digestion of fermented food wastes and sewage sludge after thermophilic acid fermentation of food wastes. The co-digestion of thermophilic acid fermented food wastes and sewage sludge was performed by semi-continous method in mesophilic anaerobic digestion reactor. It showed great digestion efficiency as the average SCOD and VS removal efficiency in organic loading rate 3.30g VS/L.d. were 74.2% and 73.6%, and the gas production rate and average methane content were 0.440 L/g $VS_{add}.d$ and 66.5%, respectively. Based on the results of this study, the co-digestion of thermophilic acid fermented food wastes and sewage sludge in sewage treatment plant is able to improve treatment efficiency of anaerobic digestion reactor and to dispose food wastes simultaneously, and was proved excellent economical efficiency comparing with any other treatment methods.