• Journal of Environmental Science International
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• v.23 no.7
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• pp.1269-1275
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• 2014

Ecotoxicity assessments with the physiochemical water quality items and the bioassay test using Daphnia magna were conducted for 18 selected effluents of 6 industrial types (metal processing, petroleum refining, synthetic textile manufacturing, plating, alcohol beverage manufacturing, inorganic compound manufacturing) being detected toxicity from industrial effluent in Ulsan city, and the interrelationship between total toxic unit (${\Sigma}TU$) and concentrations of Water Quality Conservation Act in Korea were investigated. The average toxic unit(TU) of effluents for 6 industrial types displayed the following ascending order: petroleum refining (0.2) < synthetic textile manufacturing (0.6) < alcohol beverage manufacturing (0.9) < metal processing (1.3) ${\leq}$ inorganic compound manufacturing (1.3) < plating (3.0). These values were less than effluent permission standard. Based on the result of substances causing ecotoxicity, the correlation analysis was not easy because most of heavy metals were not detected or were less than effluent permission standard. Toxicological assessment of industrial effluent was suitable for the evaluation of the mixture toxicity for pollutant. The whole effluent toxicity test using a variety of species was needed for the evaluation of industrial wastewater.

• Journal of Digital Convergence
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• v.17 no.10
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• pp.1-12
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• 2019

In this study, TI(Toxic Index) of Daphnia toximeter corresponded to ecological toxicity standard 1 TU(Toxic Unit) was set up using Daphnia toximeter and when operating NOEC(water quality standards for drinking water) and $EC_{50}$ Daphnia toximeter alarm was issued appropriately, which enables real time ecological toxicity evaluation. I studied to get a good shot and the research was conducted by investigating domestic and international related data and conducting a preliminary study. 6 of 59 hazardous substances (As, Hg, Cr, Diazinon, Dioxane, and Phenol) recommended by the water quality monitoring items for artificial river water were selected and static, dynamic and quality management test, TI was shown to be good in other materials except Diazinon, and as a result of $EC_{50}$ spiking test, TI was matched to TU by distinguishing between 1 TU and 1 TU. in suggesting the complementary point of ecological toxicity management system and the future of research on water Daphnia toximeter.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.466-471
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• 2019

1,4-dioxane and dichloromethane are classified as carcinogenic groups in the International Agency for Research on Cancer (IARC). They are frequently released at high concentrations in an industrial wastewater effluent. The acute toxicity (24 h) of Daphnia magna for 7.53 mg/L of 1,4-dioxane in the industrial effluent was evaluated as 1.1 TU (toxic unit) and showed TU close to the effluent quality standard. Mixed substances of 1,4-dioxane and dichloromethane in the industrial effluent showed relatively high TU as compared to that of a single substance. Half maximal effective concentration (24 h $EC_{50}$) values of 1,4-dioxane and dichloromethane for the synthetic wastewater prepared in laboratory were 1,744 (0.06 TU) and 170 mg/L (0.6 TU), respectively and the toxicity was low. Nevertheless the toxicological evaluation of the mixture showed that TU values increased to 0.02, 0.04 and 0.10, respectively as 1, 5 and 10 ppm of dichloromethane was added to 100 ppm of 1,4-dioxane. And the synergistic effect was observed between two substances. But the TU value of synthetic wastewater was below 5%, lower than that of industrial effluent at the similar concentration.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.913-918
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• 2006

Both raw wastewater and effluent from a rubber products manufacturing factory were found to be toxic to Daphnia magna though the effluent satisfied current water quality standards. Thus, in order to reduce toxicity, advanced oxidation processes (AOPs) such as gamma-ray (${\gamma}-ray$) treatment and ozonation ($O_3$) were applied. A combined ${\gamma}-rays/O_3$ treatment at 20 kGy after coagulation significantly reduced toxicity of raw wastewater, changing 48-h toxic unit (TU) value from 201.21 to 23.92. However, toxicity of treated water was higher than that of effluent (TU = 12.15). This shows limitation of gamma-ray treatment to remove toxicity of raw wastewater. In case of effluent, the combined ${\gamma}-rays/O_3$ treatment at 20 kGy efficiently decomposed toxic compounds down to non toxic level. This work strongly supports the necessity of toxicity reduction evaluation as well as toxicity-based effluent management.

• Ecology and Resilient Infrastructure
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• v.2 no.4
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• pp.345-350
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• 2015

The toxicity of red mud (RM) pellets for water purification was evaluated using Pseudokirchneriella subcapitata and Daphnia magna in a lab-scale experiment. According to the algal growth inhibition test, both specific growth rates and relative growth rates of P. subcapitata decreased, and the growth inhibition rates increased ($R^2=0.97$, p<0.001) as the concentration of RM pellets in the aqueous solution increased (>1.6 g/L). Also, based on the acute toxicity evaluation test on D. magna, toxic unit (TU) values ranged between 0.00 and 2.83, and increased with an increase in the concentration of RM pellets in the aqueous solution. A correlation analysis indicated that the pH of RM pellets was statistically correlated with TU values ($R^2=0.77$, p=0.02). The environmental implication from this study is that the concentration of RM pellets in an aqueous solution needs to be lower than 4.4 g/L to keep the maximum permissible TU value less than 1.0.

• Journal of Korean Society on Water Environment
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• v.30 no.6
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• pp.632-637
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• 2014

Proficiency testing by interlaboratory comparisons is used to determine the performance of individual laboratories. In order to verify the quality of acute toxicity testing with Daphnia magna, National Institute of Environmental Research in South Korea is regularly organizing interlaboratory comparisons to estimate the analytical accuracy of different laboratories. Total 58 laboratories located in South Korea took part in interlaboratory proficiency testing scheme with three proficiency testing samples. TU(Toxic Unit) values of each laboratory were determined and robust z-score was calculated in order to evaluate the proficiency levels. Based on the robust z-score classification, 74% of the participant laboratories showed a satisfactory performance (43 laboratories). The main reason of 'unsatisfactory' performance seemed to be considered that the unsuitable management of test organism incubation system and the lack of experience on the identification of the test organism condition by effect of toxicity.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.145-149
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• 2006

Textile and pigment wastewater samples collected from an industrial complex showed toxic effect on Daphnia magna. For textile wastewater, 48 h acute toxicity of effluent was not detected while toxic unit (TU) of influent was 1.79. The toxicity of influent was completely disappeared by gamma-ray treatment at 10 kGy or by suspended solids (SS) removal. In case of pigment wastewater, both influent and effluent were toxic to D. magna though the effluent satisfied current water quality standards. Gamma-ray treatment had little effect on the toxicity reduction of pigment wastewater since the toxicity was mainly caused by metal ions, in particular, Cr(VI). This work suggests the bioassay technique for monitoring adverse effects of wastewater should be introduced, and also shows the usefulness of gamma-rays as an advanced treatment technique for textile wastewater.

• Journal of Soil and Groundwater Environment
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• v.21 no.2
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• pp.15-21
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• 2016

The objective of this study was to determine the feasibility of recycled phosphogypsum (PG) as an embankment material with soil by performing batch and column ecotoxicity experiments. A. salina, D. magna, O. latipes and S. capricornutum were selected for the experiment. The effective concentration (EC₅₀) of D. magna was the lowest value, 1.29 mg/L. The survival rates of A. salina, D. magna and O. latipes were more than 90% in the presence of PG leachate in the column test. The toxicity unit (TU) for the organisms was less than 1, indicating that no significant ecotoxicity effect was found. These findings suggested that PG could be recycled for use as an embankment and landfill material with soil.

• Journal of Korean Society on Water Environment
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• v.29 no.2
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• pp.204-211
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• 2013

In this study, the deriving optimum conditions for decolorization of Acid Orange II solution was carried using $TiO_2$ advanced oxidation process. After that, on base of the deriving results, the range of dye concentration was estimated. In addition, acute toxicity test was also carried to assess toxicity unit according to decolorization and TOC removal. In case of the blockage of light, 20 mg/L of dye solution, and 0.5 g $TiO_2$, the effect of decolorization at pH 3 was larger than at pH 6 and 10, so it was shown that decolorization is dependent on pH. The use of 5 g $TiO_2$ showed best performance of decolorization, but that of 3 g $TiO_2$ was chosen to optimum condition in considering of economical aspects. Four light sources, sun, fluorescent lamp, BLB lamp, and UV-B lamp, were used and decolorization was 99.4% and 100% at 50 mg/L, 98.6% and 99.7% at 100 mg/L for sun and UV-B lamp, respectively. In spite of the optimum condition of decolorization at pH 3, the evaluation of acute toxicity test showed highly toxic. In conclusion, although the optimum treatment of dye solution is performed, water ecology can be polluted in discharging it into water system. Therefore, it is needed to study of water ecological system with dye water treatment, and it takes all the circumstances into consideration.

• Ecology and Resilient Infrastructure
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• v.2 no.4
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• pp.330-336
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• 2015

Photocatalytic degradation of bisphenol A (BPA) in aqueous solution was investigated using $TiO_2$ nanoparticles (Degussa P25) in this study. After a 3 hr photocatalytic reaction (${\lambda}=365nm$ and $I=3mW\;cm^{-2}$, $[TiO_2]=2.0g\;L^{-1}$), 98% of BPA ($1.0{\times}10^{-5}M$) was degraded and 89% of the total organic carbon was removed. In addition, BPA degradation by photolytic, hydrolytic and adsorption reactions was found to be 2%, 5% and 13%, respectively. The reaction rate of BPA degradation by photocatalysis decreased with increasing concentration of methanol that is used as a hydroxyl radical scavenger. This indicates that the reaction between BPA and hydroxyl radical was the key mechanism of BPA degradation. The pseudo-first-order reaction rate constant for this reaction was determined to be $7.94{\times}10^{-4}min^{-1}$, and the time for 90% BPA removal was found to be 25 min. In addition, acute toxicity testing using Daphnia magna neonates (< 24 h old) was carried out to evaluate the reduction of BPA toxicity. Acute toxicity (48 hr) to D. magna was decreased from 2.93 TU (toxic unit) to non-toxic after photocatalytic degradation of BPA for 3 hr. This suggests that there was no formation of toxic degradation products from BPA photocatalysis.