• Journal of Environmental Impact Assessment
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• v.24 no.5
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• pp.397-406
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• 2015

The different compliance concentration of effluent limit is applied to effluent discharged from public sewage treatment works(PSTWs) in each watershed on the basis of water quality thereof in accordance with the enforced Watershed Sewer System Maintenance Plan in 2013. It is necessary to set the compliance concentration of effluent limit for PSTWs in watershed sewer system, in order to achieve water quality criteria for regional watersheds or target water quality under TMDL program. Watershed Environmental Agencies establish the Watershed Sewer System Maintenance Plan and set the compliance concentration of effluent limit for PSTWs under the plan. The agencies have a plan to apply strengthened effluent BOD concentration limits for PSTWs in I to IV area grade, respectively. Effluent BOD concentration limits will be strengthened from 5~10 mg/L to 3 mg/L in II~III area grade, from 10 mg/L to 5 mg/L in IV area grade. Uniform application of effluent BOD concentration limits to PSTWs in the watershed sewer system need to be complemented considering type of sewage treatment technology employed and watershed characteristics. Therefore, this study presents assessment methodology which analyze for the compliance concentration of effluent limit to affect water quality of discharge watershed using simulation model for the Jinwee-stream watershed.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.1
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• pp.75-84
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• 2011

This study was conducted to provide a basic information for the establishment of operation and treatment processes in sewer system of Nakdong river basin to minimize the overall pollutants loading to water body. Sewage flowrates were regularly measured and monitored at various sampling points of newly-built separated sewer system located in G City GA sites. To assess the inflow sewage flowrate, various calculating methods such as water-use evaluation, average-minimum daily flow quality evaluation, minimum daily flow evaluation, night water-use evaluation were used. Average I/Is were calculated except water-use evaluation. Average I/Is were found to be 6.5 $m^{3}/d$, 3.5 $m^{3}/d$, 7.7 $m^{3}/d$ at GA-1, GA-2, GA-3 points respectively. I/I ratios of three areas were found to be 4.8 %, 2.0 % and 2.7 % respectively and were obviously lower than those of the other separated sewer systems as shown in the previous studies.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.5
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• pp.65-77
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• 2014

The ecosystem of Jaemin stream, flowing into the center of Gongju-si, had been damaged by low water quality and lack of water quantity of the steam. However, after applying the SSB (Sustainable Structured wetland Biotop) system to the flood plain and the upstream of Jaemin stream, the efficiency of ecological water purification and ecological restoration are as follows. Through the constant maintenance and monitoring from year 2009 to year 2013 after restorative design and construction the average influent concentration of BOD5 was 4.2 mg/L, and the average effluent concentration was 1.8 mg/L, reaching ecological water purification rate of 57%. As for the T-N, the average influent concentration was 9.983 mg/L, and the average effluent concentration was 6.303 mg/L, showing the rate of 37%. For the T-P, the average influent concentration was 0.198 mg/L, and the average effluent concentration was 0.098 mg/L, being the rate of 51%. The vegetation of Jaemin stream monitored for 2 years after the restoration was composed of 51 species in 28 families which show high ratio of planted native species. As for the animals in the site, 5 species in 3 families of reptiles and amphibians, 34 species of 23 families of birds, and 3 species in 2 families of mammals were monitored, indicating that the bio-diversity of the site has improved, as well.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.754-760
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• 2010

This study was carried out not only to evaluate optimal operating condition to increase biogas production, but also to estimate feasibility of renewable energy from anaerobic digester of sewage sludge. Semi- continuous Fed and Mixed Reactors (SCFMRs) were operated in various condition to quantify the reactor variables. The result of SCFMR operation showed that the biogas productivity and total volatile solids (TVS) removal of total solids (TS) 4% reactor at hydraulic retention time (HRT) 20 days with Organic Loading Rate (OLR) of $1.45kg/m^3-d$ were $0.39m^3/m^3-d$ and 26.7%, respectively which was two times higher than that of TS 2.5% reactor. Consequently the daily biogas production of $20,000m^3$ would be possible from the total volume of $52,000m^3$ of anaerobic digesters of the municipal wastewater treatment plant in D city. In feasibility study for the Biogas utilization, combined heat and power system (CHP) and CNG gasification were examined. In case of CHP, the withdrawal period of capital cost for gas-engine (GE) and micro gas-turbine (MGT) were 7.7 years and 9.1 years respectively. biogas utilization as Clean Natural Gas (CNG) shows lower capital cost and higher profit than that of CHP system. CNG gasificaion after biogas purification is likely the best alternative for Biogas utilization which have more economic potential than CHP system. The withdrawal period of capital cost appeared to be 2.3 years.

• Journal of the Korea Convergence Society
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• v.11 no.10
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• pp.213-217
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• 2020

An eco-friendly water purifier was developed using natural minerals, plants, and sludge from water purification plants. A wastewater complex treatment system using this water purification agent was developed. The wastewater complex treatment system goes through the process of inflow of contaminated water, input of water purification agent, operation of a pressurized flotation device, sludge flotation, sludge collection and treatment water discharge. This device was applied to the removal of green algae in livestock desorption liquid, broiler washing water, factory wastewater, sewage treatment plant and pond to obtain excellent removal rate. The use of natural water purification agents for organic waste purification has not been investigated.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.4
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• pp.385-398
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• 2007

It was analysed that spatial and temporal change patterns of general water quality constituents were measured monthly from 2002 to 2005 in Jumunjin Harbour. The measured constituents are temperature, salinity, pH, SS and DO. Concentration difference of upper lower layer for general water quality constituents was small. Temperature and DO concentration show the clear difference at temporal concentration change pattern, but SS, pH and salinity have irregular change pattern. Also, water quality improvement effect of seawater exchange facilities and sewage treatment plants is analysed quantitatively using averaged spatial and temporal data set. From this result, it is found that effect of sewage treatment plants is small and seawater exchange facilities at zone 1 and 2 is clear concentration reduction effect to be about 26% and 16%, respectively. After sewage treatment plants operation, DO concentration reduced about 10% at inner zone of Jumunjin Harbour, the other side, after seawater exchange facilities concentration DO concentration increased about 10%. DO concentration at 2005 estimated little than that of 2002, it is concluded that a yearly change of DO concentration has about 10%.

• 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 Environmental Science International
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• v.15 no.10
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• pp.975-982
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• 2006

This study has been conducted to optimum operating conditions for effective acid fermentation according to OLR(organic loading rate) in the mesophilic and thermophilic acid fermentation process. The results are summarized as follows. In order to obtain reasonable acid fermentation efficiency in performing acid fermentation of food wastes in thermophilic condition, organic loading rate was required below 20 gVS/L.d. As $SCOD_{Cr}/TKN,\;SCOD_{Cr}/T-P$ of thermophilic acid fermented food wastes In organic loading rate 20 gVS/L.d were 18.9, 73.4 respectively, it was possible to utilize as external carbon source for denitrification in sewage treatment plant after solid-liquid separation as well as co-digestion of fermented food wastes and sewage sludge.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.816-821
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• 2017

An integrated slow mixing/sedimentation and net fit fiber filtration system has been developed to reduce the high concentrations of suspended solid (SS) and total phosphorus (T-P) in the reject water from sewage/wastewater. A filtration device used in this experiment consists of coagulation, in-line mixing, air injection, slow mixing/sedimentation, and filtration processes. The performance test using this device was carried out with six operational modes for reject water from sewage treatment plant. Experimental conditions used were 16.7, 33.3, 41.7 and 50.0 ton/day of flow rate and 2~4 of Al/P molar ratio. By injection of coagulant in each operational mode, the high removal efficiencies of SS and T-P were obtained, but continuous operation time was decreased to 7.8~11.4 min in most modes. However, when the Mode 5 of the developed filtration device was applied, the continuous operation time was maintained up to 88.2 min. Also, it was found that the continuous operation time in the Mode 5 using the developed system was increased from 8 to 11.3 times longer than those in other modes. Backwashing flow rate was also very low at 5.4% of total filtered water. Therefore, it can be concluded that the Mode 5 of the developed filtration system was the most efficient treatment method for the removal of high concentrations of SS and T-P.

• Journal of Environmental Science International
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• v.23 no.5
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• pp.853-859
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• 2014

The purpose of this study was to improve low digestibility in anaerobic digestion facility of the sewage treatment plant. To perform this research, sludge digestion and digestion gas purification facilities in sewage treatment plant was applied. In the result of this study, it was very effective for sludge reduction from the improvement of digestive efficiency. In addition, it was confirmed that high purity $CH_4$ (methane) was produced. This results can be useful as basic data to improve the low digestibility in anaerobic digestion processes.