• Journal of Korean Society of Water and Wastewater
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• v.29 no.4
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• pp.503-510
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• 2015

The objective of this study is to analyze the investment adequacy of the projects implemented according to the master plan on sewerage rehabilitation at Seoul. The planned and actually implemented ratio of invested money on sewage treatment plants (STPs) to sewers were compared in two temporal periods. Though the planned ratio of investment on STPs to sewers was 50:50 (in 2009-2020), the actual implemented ratio in 2009-2013 was 34:66. Until 2020, the greater investment ratio on STPs to sewers should be made considering the necessity of coping with stricter legal compliance on advanced treatment, stormwater treatment and so on. The priority of the planned and partially implemented projects among four STPs and at each STP was evaluated. Considering only the performance indicator of reduced load of BOD, T-N, T-P per the capacity of each STP facility, the performance among four STPs was shown as Jung-Rang>Tan-Cheon>Seo-Nam>Nan-Ji. The reverse order of the performance results in the past may be considered for future investment priority, but the efficiency of operation implemented at each STP, deteriorated status of each STP, investment in the past and so forth should also be considered. As for the priority of projects conducted within each STP, projects related to legal compliance (such as advanced tertiary treatment, stormwater treatment, etc.) have highest priority. Odor-related project and inhabitant-friendly facility related projects (such as building park on STPs, etc.) has lower priority than water quality related projects but interactivity with end-users of sewerage should also be important.

• Korean Journal of Ecology and Environment
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• v.34 no.2 s.94
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• pp.126-132
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• 2001

Urbanization and population increase result in the construction of STPs (Sewage Treatment Plants). Discharge from STPs greatly influences on the water quality in the stream which receives discharges. The decision of STP location should be considered with the discharge capacity of STP and self-purification of river in the water quality perspectively. In this study, a change of dissolved oxygen (DO) in a river being affected by STP discharge was simulated by the STELLA model. Minimum DO was 4.98 ppm in 42.6 km downstream of STP. Approximately, it takes 8days to recover the DO by the self-purification and this location is 340 km down-stream from the STP. If the model run for the consideration of the self-purification without phytoplankton algorithms, minimum DO was 4.92 ppm. It took 0.25 day longer to be the minimum DO than that with the phytoplankton functions. Without the phytoplankton algorithm, it took 11days to recover the DO. This proves the importance of phytoplankton in the self-purification processes. Additionally, the effect of adjacent STP discharge should be considered in the construction of new STP.

• Korean Journal of Microbiology
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• v.47 no.1
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• pp.38-49
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• 2011

Bioaerosols generated from wastewater treatment plants may create health risks for plant workers and nearby residents. To determine the levels of culturable airborne bacteria and fungi in bioaerosols, samples were seasonally collected above and near the aeration tanks of one feces-urine and three sewage treatment plants in Ulsan, Korea with an impaction-type sampler. In the feces-urine treatment plant, concentrations of heterotrophic bacteria were between $1.3({\pm}0.2){\times}10^3$ and $2.6({\pm}1.2){\times}10^4$ MPN/$m^3$ above the aeration tank and between $1.7({\pm}1.0){\times}10^2$ and $7.2({\pm}2.2){\times}10^3$ MPN/$m^3$ near the aeration tank. Coliform bacteria were detected both above and near the aeration tank. In cases of sewage treatment plant, the numbers of heterotrophic bacteria ranged from $1.9({\pm}1.2){\times}10^1$ to $1.8({\pm}1.2){\times}10^4$ MPN/$m^3$ above the aeration tank and from $5.0({\pm}2.8){\times}10^0$ to $6.6({\pm}2.0){\times}10^3$ MPN/$m^3$ near the aeration tank. At reference sites, the concentrations of heterotrophs in ambient air were measured between $7.0{\times}10^0$ and $2.7{\times}10^1$ MPN/$m^3$. When we isolated and tentatively identified heterotrophic bacteria, Pseudomonas luteola was the most dominant species in bioaerosols from wastewater treatment plants, whereas the most abundant one in reference samples was Micrococcus sp. When we measured fungal concentrations in bioaerosols, they were rather similar regardless of sampling locations and seasons, and such genera as Cladosporium, Alternaria, and Penicillium were commonly identified.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.4
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• pp.337-348
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• 2018

As the issue of microplastics (MPs) detection in tap water was raised in other countries in 2017, monitoring of MPs in drinking and source water, and sewage treatment plant (STP) effluents was initiated. This study intends to look into other studies on MPs in STPs at home and abroad, and review the characteristics of MPs and their removal efficiencies in the STPs, the risk and effect of MPs on watersheds, and management practices in order to help better understand MPs in STPs. To manage MPs effectively in STPs, it is necessary to investigate the detection of MPs discharged from STPs, do research on human health risk and control measures, and build a monitoring system including standardized analytical methods.

• 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.

• Applied Chemistry for Engineering
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• v.33 no.5
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• pp.532-537
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• 2022

The need for obtaining treated wastewater that meets high quality standards for discharge or reuse necessitates the use of highly efficient wastewater treatment techniques. In the present study, experiments have been carried out to reduce the concentration level of biological oxygen demand (BOD), chemical oxygen demand (COD), and total dissolved solids (TDS) from the wastewater sample. Treatment of sample of a real municipal wastewater collected from a sewage treatment plant (STP) was carried out in an electrochemical membrane bioreactor (EMBR). The EMBR was operated continuously for five days, and readings were taken at regular intervals. This paper has experimental results conducted in EMBR that indicate reduction of BOD, COD, and TDS levels of up to 32.25%, 29.25%, and 31.93%, respectively. Further, it was observed that a current of magnitude of 0.00752 mA was generated due to the metabolic activities of bacteria present in municipal wastewater, which gradually decreased day by day due to the decay of bacteria.

• Environmental Engineering Research
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• v.14 no.3
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• pp.186-194
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• 2009

Understanding the environmental fate of human and animal pharmaceuticals and their risk assessment are of great importance due to their growing environmental concerns. Although there are many potential pathways for them to reach the environment, effluents from sewage treatment plants (STPs) are recognized as major point sources. In this study, the removal efficiencies of the 43 selected priority pharmaceuticals in a conventional STP were evaluated using two simple models: an equilibrium partitioning model (EPM) and STPWIN$^{TM}$ program developed by US EPA. It was expected that many pharmaceuticals are not likely to be removed by conventional activated sludge processes because of their relatively low sorption potential to suspended sludge and low biodegradability. Only a few pharmaceuticals were predicted to be easily removed by sorption or biodegradation, and hence a conventional STP may not protect the environment from the release of unwanted pharmaceuticals. However, the prediction made in this study strongly relies on sorption coefficient to suspended sludge and biodegradation half-lives, which may vary significantly depending on models. Removal efficiencies predicted using the EPM were typically higher than those predicted by STPWIN for many hydrophilic pharmaceuticals due to the difference in prediction method for sorption coefficients. Comparison with experimental organic carbon-water partition coefficients ($K_{ocs}) revealed that log KOW-based estimation used in STPWIN is likely to underestimate sorption coefficients, thus resulting low removal efficiency by sorption. Predicted values by the EPM were consistent with limited experimental data although this model does not include biodegradation processes, implying that this simple model can be very useful with reliable Koc values. Because there are not many experimental data available for priority pharmaceuticals to evaluate the model performance, it should be important to obtain reliable experimental data including sorption coefficients and biodegradation rate constants for the prediction of the fate of the selected pharmaceuticals.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.9
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• pp.648-658
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• 2014

We examined the effects of pollutants into sub-basin on the water quality and loading based on data surveyed during January-December 2013 from 13 sites of 5 streams in the Jinwi watershed. We used the contour plot and Kruskal-Wallis rank sum test to analyze seasonal variation of water quality and loading and Pearson correlation analysis to assess the relationships between pollutants and loadings. The significantly higher seasonal variation were SS, TN and TOC as compared to other water quality constituents (P < 0.001). A significant interaction existed between the effects of human population and the effects of discharge of Sewage Treatment Plant (STP) on water quality and loading, especially for the spring and winter seasons. It is necessary to control discharge water of sewage and wastewater from industrial facilities and to make full use of the watershed management system such as TMDLs in operation since 2012 for improvement in stream water quality.

• Journal of Environmental Science International
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• v.23 no.7
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• pp.1253-1268
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• 2014

This study was investigated twenty two hazardous chemicals compounds for effluents of nine sewage treatment plants (STPs) and one waste water treatment plant (WWTP) in the Nakdong Ri-ver Basin. They are eleven phthalates(DMP, DEP, DIBP, DBP, BEEP, DNPP, DHP, DCP, DEHP, DNOP, Dinonyl phthalate, seven aliphatic hydrocarbons(n-Tridecane, n-Tetradecane, n-Pentadecan-e, n-Hexadecane, n-Heptadecane, n-Octadecane, n-Nonadecane, Isoquinoline, 2-Chloropyridine, 2-N-itrophenol, and Benzophenone. The twenty two compounds were analyzed by gas chromatograp-hy mass spectrometry (GC/MS) with liquid-liquid extraction (LLE). Twenteen of twenty two subs-tances were detected. They were DMP, DEP, DIBP, DBP, DEHP, n-Tetradecane, n-Pentadecane, n-Heptadecane, n-Octadecane, n-Nonadecane, Isoquinoline and Benzophenone. Among these, DEHP, DEP and Benzophenone were most frequently observed. They were obtained as $ND{\sim}36.881{\mu}g/L$, $ND{\sim}0.950{\mu}g/L$, $ND{\sim}2.019{\mu}g/L$, respectively. When the substances were calculated the average concentration at 10 points, the maximum average detection concentration was investigated at the Dalseocheon STP.

• Journal of Korean Society on Water Environment
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• v.27 no.3
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• pp.286-292
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• 2011

Preparing for the Standards for Effluents which will be strengthen from 2012, many ways like remodellings and repairs of sewage treatment plant (STP) are considered. The treatment of the recycle water from the sludge treatment process contains high-strength organic compounds and nitrogen is considered as alternative. In the treatment of high-strength nitrogen, nitritation has more economic advantages than nitrification. In this study, lab-scale reactor was operated at the $35^{\circ}C$, $20^{\circ}C$ and $10^{\circ}C$ conditions using effluent of anaerobic digester to investigate the nitrogen removal by nitritation. Long-term stable nitritation was achieved at the $35^{\circ}C$, $20^{\circ}C$ but $10^{\circ}C$. In the stable nitritation states, nitrite conversion was higher at the high temperature of $35^{\circ}C$ than the room temperature of $20^{\circ}C$. Also shorter solid retention time (SRT) was needed to induce high nitrite conversion at the high temperature of $35^{\circ}C$. It was showed that temperature and SRT are important factors to induce nitritation.