• Journal of Korean Society of Environmental Engineers
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• v.34 no.8
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• pp.549-556
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• 2012

T-P removal efficiency was analyzed according to the metal to initial T-P ratio (mole basis) with respect to the samples from different WWTPs having various initial T-P and SS conditions. Also, operating costs were calculated based on the injected coagulant amount and the amount of sludge production. Most experiments were conducted by the standard jar-test protocol. Molar ratio of coagulant dose was varied considerably according to the initial SS concentration range in secondary clarifier effluent samples which had above 0.5 mg/L of initial T-P. Based on 90% T-P removal efficiency, results were: At the initial SS range of below 10 mg/L, Alum (8%) = 11 mol Al/mol P needed and PAC (17%) = 9.6 mol Al/mol P needed; At the initial SS range of above 10 mg/L, Alum (8%) = 3.9 mol Al/mol P needed and PAC (17%) = 3.2 mol Al/mol P needed.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.2
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• pp.214-219
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• 2007

66 micropollutants analyses in 9 wastewater treatment plants(WWTPs) along Nak-dong river were implemented to identify the concentrations and removal efficiencies before and after treatment processes. As a result of study, the concentration levels discharged from WWTP effluents to water system were below the water quality criteria and the levels of other studies. The removal efficiencies were 84.6%(DAF/CCR) and 81.6%(AC) for 1,4-dioxane. Phenol, Clphs and PAHs were removed 94.6%, 66.4% and 80.6% respectively by the activated sludge(AS) process. The removal efficiencies of Clbzs were 45.3% for the activated sludge(AS) process and 60.6% for the activated carbon(AC) process. However, other processes besides AS and AC, the removal efficiencies of Clbzs were very low(<20%). The sand filtration(SF) process that could remove particle matters showed the best efficiency for PCDDs / Fs removal$(\geq99%)$. However, in case of relatively low PCDDs/Fs concentration level in influent, the removal efficiency was not so high$(\leq50%)$.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.735-742
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• 2008

In order to evaluate the levels and distribution patterns, the concentrations of PAHs and chlorophenols were investigated in sludge samples discharged from 6 WWTPs located along Nak-dong river and 7 STPs in Busan, Korea. Levels of 16 PAHs and 19 chlorophenols in sludge samples ranged from 1.28 to 44.9 mg/kg dry wt. and from 213 to 3,850 $\mu$g/kg dry wt., respectively. Levels of PAHs in sludge samples except I5 and S4 were detected lower than those of previous studies. The distribution patterns of PAHs and chlorophenols varied with industrial wastewater sludge samples because industrial wastewater sludge had different industrial input sources. However, the distribution patterns of PAHs and chlorophenols in sewage sludge were pretty similar. Phenanthrene, fluoranthene and pyrene were dominant and the fractions of these 3 PAHs relative to 16 PAHs in sewage sludge ranged from 30.8 to 50.7%. 2-chlorophenol is dominated in most sewage sludge samples and the fraction ranged from 36.0 to 66.8%.

• Analytical Science and Technology
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• v.25 no.4
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• pp.236-241
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• 2012

There are many industrial factories in the central Nakdong river basin and have been occurred water pollution accidents by hazardous chemicals such as phenol, 1,4-dioxane and perchlorate. In this study, ten compounds of semi-volatile organic compounds (SVOCs) (dichlorvos, toluene-2,4-diisocyanate, 4,4'-methylenedianiline, 4,4'-methylenebis (2-chloroaniline), diethyl phthalate, di-n-butyl phthalate, butyl benzyl phthaltate, bis (2-ethylhexyl) adipate, benzophenone, 4,4'-bisphenol A) of hazardous chemicals which may be potentially discharged into the Nakdong river, were determined by gas chromatography-mass spectrometry (GC-MS) with disk-type solid-phase extraction. Accuracy and precision were in the range of 75.6~110.5%, and 4.6~12.7%, respectively and recovery was in the range of 72.4~127.9%. Three compounds (bis (2-ethylhexyl)adipate, benzophenone, 4,4'-bisphenol A) were detected in industrial wastewater such as wastewater treatment plants (WWTPs) and wastewater discharge facilities in the Nakdong River basin.

• Journal of Wetlands Research
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• v.24 no.4
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• pp.345-353
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• 2022

A wastewater treatment plant (WWTP) is a major gateway for the engineered nano-particles (ENPs) entering the water bodies. However existing studies have reported that many WWTPs exceed the No Observed Effective Concentration (NOEC) for ENPs in the effluent and thus they need to be designed or operated to more effectively control ENPs. Understanding and predicting ENPs behaviors in the unit and \the whole process of a WWTP should be the key first step to develop strategies for controlling ENPs using a WWTP. This study aims to provide a modeling tool for predicting behaviors and removal efficiencies of ENPs in a WWTP associated with process characteristics and major operating conditions. In the developed model, four unit processes for water treatment (primary clarifier, bioreactor, secondary clarifier, and tertiary treatment unit) were considered. Additionally the model simulates the sludge treatment system as a single process that integrates multiple unit processes including thickeners, digesters, and dewatering units. The simulated ENP was nano-sized TiO₂, (nano-TiO₂) assuming that its behavior in a WWTP is dominated by the attachment with suspendid solids (SS), while dissolution and transformation are insignificant. The attachment mechanism of nano-TiO₂ to SS was incorporated into the model equations using the apparent solid-liquid partition coefficient (Kd) under the equilibrium assumption between solid and liquid phase, and a steady state condition of nano-TiO₂ was assumed. Furthermore, an MS Excel-based user interface was developed to provide user-friendly environment for the nano-TiO₂ removal efficiency calculations. Using the developed model, a preliminary simulation was conducted to examine how the solid retention time (SRT), a major operating variable affects the removal efficiency of nano-TiO₂ particles in a WWTP.