• Applied Biological Chemistry
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• v.41 no.2
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• pp.181-186
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• 1998

The effects of sewage treatment on characteristics of sludge as a composting material were investigated for a year during the initial operation at the full-scale Chunan sewage treatment plant. Due to the shortage of design capacity of belt press, a sludge dewatering unit, non-volatile solids were recirculating and concentrating in the treatment plant, resulting in an increase of MLSS and a decrease in F/M ratio at the activated sludge system. Special attention is required for long term operations since the increase of non-volatile solids in the plant would deteriorates the treatment efficiency. The sewage sludge of the Chunan sewage treatment plant showed 79.5% of water content, 11.6% of organic content, and C/N ratio of 6.1, and contained As 1.8 mg/kg, Cd 27 mg/kg, Hg <0.1 mg/kg, Pb 54 mg/kg, T-Cr 370 mg/kg, and Cu 1,100mg/kg of heavy metals. In order to be used as raw material for optimum composting, the sewage sludge requires bulking agents for moistrure/porosity control and a carbon source for adjusting C/N ratio. However, the sewage sludge is not adequate as a soil conditioner after composing due to a high content of heavy metals. If the sewage sludge has to he used as a soil conditioner after composting, it as required to identify and remove tire industrial wastewater portions in tire influent of the plant since heavy metals in the influent were mostly concentrated in dewatered sludge.

• Korean Journal of Environmental Agriculture
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• v.5 no.1
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• pp.24-29
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• 1986

This study was carried out to determine the heavy metal contents in effluents, soils and plants grown on the soils from 1982 to 1983. The heavy metal pollution of Keumho river was resulted from Sincheon, Kongdancheon and Dalseocheon. The urban sewage influxes in Sincheon and Dalseocheon whereas the industrial wastewater flows in Kongdancheon. The average heavy metal contents of effluents in these streams exceeded the Korean Standard Environmental value. The high level of heavy metal contents in soils and plant tissues should be originated from the polluted river water. The heavy metal contents of soils were significantly positively correlated with that of plant.

• Korean Journal of Environmental Biology
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• v.19 no.1
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• pp.59-69
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• 2001

Among the biodegradability tests, TOC-HANDAI and OECD method were utilized to examine the degree of biodegradation of endocrine disruptors, Bisphenol A (BPA) and Nonylphenol. Both methods used natural water microcosms and measured their biodegrada-bilities of BPA and Nonylphenol, in terms of TOC or DOC degradation with time for 28 days. Biodegradabilities for BPA, 73-78% with TOC-HANDAI method and 77-81% with OECD method were obtained respectively at the end of experiment. There was no difference in BPA degradation between two methods. BPA degradation was described by two distinct first order decay rates (k$_1$ and k$_2$) which could be separated by a simple visual fitting. Most of the initial decay reaction accelerated within 1-7 days with k$_1$of 0.24-0.34 $day^{-1}$. And the following another long term first order decay coefficient (k$_2$) showed 0.02-0.05 day$^{-1}$ with much flat slope. About 20-25% of initial BPA remained at the end of experiment. It suggests that the remaining TOC components in BPA biodegradation considered to be refractory metabolites of BPA. Nonylphenol at each sampling point was appeared to be mineralized 20-48% of initial TOC concentration. Consequently Nonylphenol seems more recalcitrant against biodegradation. BPA was not detected in the detection limit of ppb in the watershed of Daechung reservoir and Kum river. However 25 ppb concentration of BPA was detected at the influent of industrial wastewater treatment plant in Taejon.

• Korean Journal of Environmental Biology
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• v.32 no.4
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• pp.271-285
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• 2014

Aluminum flows into the river from the abandoned mine leachate, industrial wastewater, and sewage and is responsible for acute toxicity in aquatic organisms. Recently, the number of reports have indicated the increased toxicity in a variety of aquatic organisms' due to the aluminum toxicity. In this study, we reviewed the toxicity of aluminum on aquatic invertebrates, fishes and amphibians and suggested the guideline for management of aluminum residues in aquatic environment and strategies for aluminum toxicity evaluation. In aquatic animals aluminum complexes evoke gill dysfunction primarily, the cytotoxicity, genotoxicity, oxidative stress, disruption of endocrine function, reproductive success, metabolism and homeostasis. Notably, at environmentally relevant concentration, aluminum complex can alter the hormone levels in fish in acidic condition. Further, since the solubility of aluminum is higher in the acidic and basic conditions, thus it is likely that the toxic effects of aluminum may not only occur in acidic water near the abandoned mines but also in lakes and rivers, where pH is raised by algal bloom.

• Korean Journal of Ecology and Environment
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• v.45 no.2
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• pp.210-217
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• 2012

This study investigated the water quality of effluents from the wastewater treatment plants, located at the Gumi Complex 4, Gumi, and Wonpyong, in Gumi. DOC accounted for higher than 70% of TOC, and oxidation efficiencies, calculated from carbon, were 13~43% for BOD and 37~73% for CODMn, respectively. Based on the biological decomposition experiments, R-DOC account for higher than 70% of DOC, mostly being occupied by refractory organic matters. This indicated that the biodegradable organics occupied more proportions of organic loadings than the refractory organics. The effect of the organics from a discharge of a sewage treatment plant on rivers, Gumi industrial Complex 4, Gumi, and Wonpyong on lower streams of the Nakdong River were found to be 15%, 6% and 16% respectively. The ratio of 15% suggests that comparatively, no large portions of TOC loadings are occupied, but the problem is that the biodegradable organic matters occupy a lot more proportions than that of the refractory organic matters. Thus, it is highly estimated that the refractory organics can gradually increase the pollution level of organics and precursors of disinfection by-products to the down-stream water treatment plants.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.266-271
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• 2007

Bisphenol A (BPA) has been widely used as a monomer for production of epoxy resins and polycarbonate plastics. The annual production of BPA exceeds 640,000 metric tons in worldwide. BPA, a suspected phenolic endocrine disrupter, is moderately soluble and frequently detected in industrial wastewater. To date, HPLC and GC has been used for BPA analysis. However, HPLC and GC-analysis need high operation lost, experts, and an elaborate pre-treatment of samples, and is difficult to apply on-time and mass analysis. Therefore, simple, mass and rapid detection of BPA in environments is necessary. In the present study, spectrophotometric method of BPA quantification was developed. Based on blue-color product formation with BPA and ferric chloride/ferricyanide under the optimized conditions, the standard curve was acquired $({\lambda}_{750}=0.061\;BPA\;[{\mu}M]+0.07155,\;R^2=0.992)$. Using an established method, the BPA contents in the soil extract, and different water samples and living products, including disposable syringe, cup and plastic tube, were analyzed. The results suggested that the method is useful for BPA determination from different massive samples. Since the BPA metabolites, nontoxic 4-hydroxyacetophenone or 4-hydroxybenzaldehyde, did not form blue-color product, this method is also useful to screen a microorganism for BPA bioremediation.

• Clean Technology
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• v.12 no.4
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• pp.191-197
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• 2006

Polymerization in supercritical carbon dioxide has been getting attention since it is easier to separate the remaining reactants from product polymer and since it is a cleaner process that produces neither wastewater nor air pollutants, compared to the conventional polymerization processes. In this study, poly(vinyl acetate) (PVAc) that is necessary in producing poly(vinyl alcohol) (PVA) with a lot of industrial applications was manufactured in the presence of supercritical carbon dioxide for the second time in the world. A poly(dimethylsiloxane)(PDMS)-derivative surfactant and three initiators were employed in the polymerization of vinyl acetate (VAc) at 338.15 K and 34.5 MPa. Investigation was carried out to find out the effect of the amounts and types of initiators and surfactants as well as the effect of reaction time on the yield and the molecular weight of PVAc. The weight average molecular weight (Mw) of PVAc was in the range of 60,000 ~ 140,000 g/mol, and the number average molecular weight was in the range of 30,000 ~ 70,000 g/mol. The yield of PVAc was spread over 10 ~ 80%, based on the amount of VAc monomer.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.4
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• pp.5-13
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• 2017

With the purpose of energy recovery from sludge having calorific value as fuel we investigated the current status and characteristics of sludge in Korea in order to understand the type and amount of sludge that can recover energy. 'The Status Report on Waste Generation and Treatment in Korea' announced that 152 million tons of wastes were generated nationwide in 2015 and 9.2 % of the whole waste disposed into landfills which includes 15.1 % of the total industrial wastes. The average of upper calorific values of sewage sludge was 3,021 kcal/kg and that of wastewater sludge was 2,472 kcal/kg respectively. In order to determine the sludge as fuel, each correlations between calorific value, carbon content and combustibility ratio were evaluated. In the study, the current status and characteristics of sludge in Korea were investigated in order to understand the type and amount of sludge as fuel to recover energy. It is predicted that if the energy of sludge having a calorific value of 6 MJ/kg($${\sim_=}1,500kcal/kg$$) or more is recovered as fuel, the amount of the sludge disposed into landfills can be reduced about 40 %.

• The Journal of Engineering Geology
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• v.16 no.4 s.50
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• pp.373-379
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• 2006

We investigated the relationship of the organic pollutant index in wastewater where the high percentages of an organic load to a water body was found. Measuring of TOC was to identify the relationship with COD and BOD which were used already. The correlation coefficient (r) of TOC/COD, BOD/COD and TOC/BOD were effected by the types of industry such as paper, textile, chemical, food and metal industries. In food industry it was found that the highest correlation coefficient (r) of TOC/COD, BOD/COD and TOC/BOD as 0.967, 0.969 and 0.990, respectively. There is low correlation coefficient in many cases. Hence it was impossible that the use of TOC for the water standard or monitoring instead of COD and BOD directly. However it can be used as alternative index to management a water process in the case of waste water where there was found high correlation coefficient of TOC/ COD, BOD/COD and TOC/BOD. It was sure that the water quality of river body can be protected if we use these the relationship among organic index.

• Environmental Engineering Research
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• v.13 no.3
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• pp.131-135
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• 2008

In this study, Fe(VI) was employed as a multi-functional agent to treat the simulated industrial wastewater contaminated with Cu(II)-EDTA through oxidation of EDTA, decomplexation of Cu(II)-EDTA and subsequent removal of free copper through precipitation. The decomplexation of $10^{-4}\;M$ Cu(II)-EDTA species was performed as a function of pH at excess concentration of Fe(VI). It was noted that the acidic conditions favor the decomplexation of Cu(II)-EDTA as the decomplxation was almost 100% up to pH 6.5, while it was only 35% at pH 9.9. The enhanced degradation of Cu(II)-EDTA with decreasing the pH could be explained by the different speciation of Fe(VI). $HFeO_4^-$ and $H_2FeO_4$, which are relatively more reactive than the unprotonated species $FeO_4^{2-}$, are predominant species below neutral pH. It was noted that the decomplexation reaction is extremely fast and within 5 to10 min of contact, 100% of Cu(II)-EDTA was decomplexed at pH 4.0. However, at higher pH (i.e., pH 10.0) the decomplexation process was relatively slow and it was observed that even after 180 min of contact, maximum ca 37% of Cu(II)-EDTA was decomplexed. In order to discuss the kinetics of the decomplexation of Cu(II)-EDTA, the data was slightly fitted better for the second order rate reaction than the first order rate reaction in the excess of Fe(VI) concentration. On the other hand, the removal efficiency of free Cu(II) ions was also obtained at pH 4.0 and 10.0. It was probably removed through adsorption/coagulation with the reduced iron i.e., Fe(III). The removal of total Cu(II) was rapid at pH 4.0 whereas, it was slow at pH 10.0. Although the decomplexation was 100% at lower pH, the removal of free Cu(II) was relatively slow. This result may be explicable due to the reason that at lower pH values the adsorption/coagulation capacity of Fe(III) is greatly retarded. On the other hand, at higher pH values the decomplexation of Cu(II)-EDTA was partial, hence, slower Cu(II) removal was occurred.