• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.542-547
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• 1998

Polyamine type polymer flocculants were synthesized and their characterization, viscosity and flocculation studies were conducted. In order to increase the molecular weight of polyamine flocculant which was prepared by polycondensation reaction from dimethylamine and epichlorohydrin, a small amount of 1,6-hexanediamine was employed. The incorporation of 1,6-hexanediamine up to 5.5 mole % replacing corresponding part of dimethylamine gave a branched type polyamine sample with increased intrinsic viscosity ([${\eta}$]=0.46 in 1 wt % aqueous NaCl solution). The amount of 1,6-hexanediamine above 5.5 mole %, however, resulted in gelation during polymerization. Utilizing raw water from Maegok potable water treatment plant, it was found that the addition of polyamine flocculant at a concentration of 1 mg/L level could reduce the amount of polyaluminum chloride (PAC) inorganic flocculant by half (15 mg/L). It was also observed that the incoporation of polyamine flocculant at 1 mg/L level was effective in the higher pH raw water, while PAC inorganic flocculating agent alone was not effective.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.257-264
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• 2006

In order to evaluate the application of Algae Online Analyzer (AOA), an instrument of automatic measurement of chlorophyll a concentration, was tested and compared with the acetone extraction method on the basis of microscopic counting of phytoplankton in field water (Paltang Reservoir). We simultaneously conducted AOA operation and extraction method with the same water sample, to compare both results of chlorophyll a measurement. Phytoplankton were enumerated by inverted microscope with the Sedgwick-Rafter chamber, and classified into the genus or species. According to the AOA measurement, the diatom most (83.6%) strongly contributed to the total chlorophyll a concentration, followed by chlorophyceae> cyanophyceae>cryptophyceae. Overall, the results of both AOA and extraction method showed a similar trend and significant correlation (r=0.87, n=302, p<0.001), however, there were some differences according to the season and species. In particular, the relationship between AOA Chl-a density of the diatom (r=0.73, p=0.010) and cyrptophyceae (.=0.83, p=0.00154) were siginificant, while chlorophyceae (r= -0.13) and cyanophyceae (r= -0.16) showed no clear relationship during the study period. Although we can not fully understand why there was difference between both mothods, AOA application for alarming algal bloom and water quality management during the algal bloom appears to be very relevant. However, the further study or technical upgrade of AOA measurement is required, especially in the case of low density of phytoplankton or species-specific measurement.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.522-526
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• 2006

To investigate the characteristics of rainwater in Daegu area, parameters such as pH, electrical conductivity, TOC, TIC and TC were analyzed on 34 samples from January to December 2005. Results revealed that higher values were measured in winter than in summer. Furthermore samples that originated from industrial and commercial areas had higher chemical concentrations and conductivity as compared with those from residential and reference areas. Seldom acid-rain occurrence was recorded(27.2%) as compared with non-acid precipitation(72.8%) incidence. Also higher organic carbon fraction(TOC) was detected(72.5%) than inorganic form(TIC)(27.5%) in terms of component ratio with TC. During frequent rainfalls, the concentration of chemicals was decreased to a degree. Conversely, lower rate of rainfall gave out higher chemical values. Thereby the improvement of air qualify in 2005 compare with 2003 report was influenced by the environment authorities' efforts to reduce air pollutions and various factors by the depression of the region's economy.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.689-698
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• 2000

The quality of stormwater runoff has been a major concern in water quality preservation. Characteristics of heavy metals and conventional pollutants in surface runoff from industrial complex, during the first flush, were not completely understood, Generally, separated sewer system is known for their water quality with untreated wastewater during storm events. In this study, the quality and characteristics of surface runoff from the industrial complex were investigated. The target area in the industrial complex catchment was divided 4 sub-areas, and the quality of stormwater runoff from the selected drainage areas was investigated using a grab sampling method. The petro-chemical industry and the junkyard discharged relatively high concentration of conventional pollutants, such as BOD, COD, SS, and TN through the first flush runoff samples. On the other hand, a higher level of heavy metals was found in the first flush runoff from the metal-mechanical industry and the scrap storage yard. For metals, Fe, Zn and Cu were the most prevalent species found in the first flush runoff from all sites for every surface runoff samples, while Pb, As, Cd, Cr and Ni were the least prevalent species and Hg was not found in any sample at any site. These results suggest that the nature of pollutants in surface runoff from the industrial complex was related to the type of industry, and the concentration of pollutants was determinated by the degree of exposed pollutant sources and the characteristic of rainfall events at the sites.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.5
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• pp.277-284
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• 2015

In order to analyze the contamination level of sediment samples taken from Chusori and Chudong areas in Daechung Reservoir, the particle size and concentrations of organics and nutrients were analyzed and phosphorus fractionation analysis was conducted. The average fraction of silt-sized particles was 92% in the sediments taken from Chudong area and Chusori area at the site adjacent to main current, which was higher than that from the upper Chusori area. The concentrations of total phosphorus in the sediments at Chusori and Chudong area were 999 (${\pm}98$) and 1,123 (${\pm}119$) mg/kg sediment, respectively. The fractions of autochthonous phosphorus, which can be readily eluted by change of environmental conditions, were much higher than those of allochthonous phosphorus, indicating the internal load can contribute the eutrophication in these areas. The concentrations of total nitrogen were over 5,600 mg/kg sediment in all samples, which is the guideline of Contamination Assessment of River and Lake Sediments of the Ministry of Environment, indicating the contamination level of total nitrogen is serious in the sediments. It is concluded that the countermeasures to manage the quality of sediments are required to improve the water quality in the Daechung Reservoir.

• Journal of the Mineralogical Society of Korea
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• v.22 no.4
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• pp.331-342
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• 2009

Groundwater samples were collected from the bedrock aquifers related with Okcheon metasedimentary rocks. Arsenic (As) concentrations in the samples varied between 0.0051 and 0.887 mg/L, with an average of 0.0248. Cations and anions of groundwaters had no relationship with As contents as well as with spatial distribution of geology in the area. Pyrite, chalcopyrite and arsenopyrite in the core samples of the monitoring wells were identified in thin section, X-ray diffraction (XRD) and electron probe microscope analysis (EPMA). It was suggested that these minerals are responsible for the As in groundwater. The groundwater showed saturations with respect to calcite $(CaCO_3)$, dolomite (CaMg$(CO_3)_2$) and Magnesite $(MgCO_3)$. $HAsO_4{^{2-}}$ activities in the groundwater samples were close to $Ca_3(AsO_4)_2(c)$ and $Mn_3(AsO_4)_2(c)$ solubility isotherms, indicating that the maximum As contents in groundwater are secondly controlled by the precipitation and dissolution of carbonate minerals due to alkaline and oxic nature of the groundwater (pe+pH>10).

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.662-669
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• 2017

This study evaluated the ecotoxicological properties of livestock waste water treated by a LID (Low Impact Development) system, using a mixture of bio-reeds and bio-ceramics as suitable bed media for a subsequent treatment process of a livestock wastewater treatment plant. The relationship between the pollutant reduction rate and the ecotoxicity was analyzed with the effluents from the inlet pilot plant, with vegetated swale and wetlands and the batch type of an infiltration trench. Each pilot plant consisted of a bio process using bio-reeds and bio-ceramics as bed media, as well as a general process using general reeds and a bed as a control group. The results indicated that, after applying the HRT 24 hour LID method, the ecotoxicity was considerably lowered and the batch type pilot plant was shown to be effective for toxicity reduction. The LID method is expected to be effective for water quality management, considering ecotoxicity by not only as a nonpoint source pollution abatement facility but also, as a subsequent treatment process linked with a livestock manure purification facility. It is necessary to take the LID technic optimization study further to apply it as a subsequent process for livestock wastewater treatment.

• Journal of Marine Life Science
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• v.4 no.2
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• pp.86-90
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• 2019

This study aimed to compare the disinfection efficiencies of the ultraviolet and plasma systems, the two systems designed and commercialized to disinfect water in aquaculture, by putting each in a 100 ℓ water tank and concentrating 1.0 ℓ of treated water to check the changes in the number of bacteria in the samples. Each system was operated for 6 hours to culture the typical seawater bacteria in the Marine agar, Thiosulfate citrate bile salts sucrose agar and Salmonella Shigella agar media, respectively, to check the number of bacteria in the media, and the changes in the number of Edwardsiella piscicida in the treated water were checked after the artificial inoculation of E. piscicida in the disinfected seawater. As a result, the two disinfection systems showed the almost similar levels of bacterial reduction efficiency between 99.5% and 99.9%. However, the result of this study showed that, with 100 ℓ of water treated for the same length of time using the two systems, the plasma system turned out to disinfect bacteria in a shorter period of time than the UV system. However, as the changes in the number of bacteria were checked for a short length of time (6 hours) in this study, it was judged that, considering the actual aquaculture environment in which the quality of water significantly changes with feed residues, excretions and coastal contamination, etc., and a lot of biofilms and organic matter exist, the plasma system would be more efficient than the UV system as the former is capable of continuously maintaining a certain level of efficiency than the latter that is limited in terms of efficiency depending on the level of turbidity and the existence of organic matter.

• Journal of the Korean GEO-environmental Society
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• v.12 no.5
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• pp.51-57
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• 2011

Generally, ready-mixed concrete(RMC) gets hardened by time, so the remaining concrete in the drum should be cleaned. But if the RMC waste water generated from this is discharged to soil without any treatment, the strong alkaline elements and heavy metals affect water and ecosystem pollution. Although about 10 to 15% of water used for cleaning in the RMC factory is discharged to soil or river, the concrete report of this affecting soil pollution has not been sufficient. Hence, in this study it was analyzed the extraction of cleaning water from RMC factories all over the country and heavy metal and pH components remaining in soil when this is penetrated to various soils having water permeability. The specimens used for the experiment are weathering soil and soils having different particle size, and it is made to be penetrated to those for 24 hours while fixed thickness of the layer is maintained. Cleaning water is divided into that before deposition treatment(sludge water) and that after deposition treatment(upper water) to be penetrated into soil, and according to the result of penetrating sludge water to soil, Cu and Mn, Fe, and Zn were found to be remained over 23 to 90%. However, it is analyzed that in upper water having deposition treatment, Cu and Mn remain as 60% or more only in weathering soil.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.302-308
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• 2022

The PdO nanoparticle with large surface area was selected to solve the environmental pollution problem at fire range caused by high energy explosives research department explosive (RDX) and high melting explosive (HMX). By simulating water pollution, RDX and HMX nitramine explosives were dissolved in water, followed by the degradation reaction at 313 K by adding PdO. In order to measure the degradation reaction rate of explosives, ¹H NMR was used, which can monitor the reaction rate without losing sample during reaction, and observe the progress of the reaction through the spectrum. The results showed that the degradation of RDX and HMX by PdO nanoparticles are pseudo-first order reaction. The degradation of explosives compounds were observed via the chemical shift and peak intensity analysis of NMR peaks. The measured rate constants for these reactions of RDX and HMX were 2.10 × 10^-2 and 6.35 × 10^-4 h^-1, respectively. This study showed that the application of PdO nanoparticles for explosives degradation is a feasible option.