• Journal of Environmental Health Sciences
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• v.30 no.3
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• pp.185-190
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• 2004

Acute aquatic toxicity of effluents discharged from five dyeing plants in Gyeong-gi province were evaluated to assess whether the current Korean water quality standards(KWQS) could protect aquatic life. Chemical analyses of all parameters regulated under KWQS, except for E-coli, were also carried out to determine regulation compliance of the samples. All the effluent samples were satisfied with KWQS except for the color in only one sample. In acute Daphnia magna toxicity tests, significant mortality was observed in one of five samples and EC50 was 12.1%(95% confidence interval 9.1-16.2), which was in compliance with KWQS. The result of the Microtox assay indicated that acute microbial toxicity existed in effluents from three out of five plants, two of which were in compliance with KWQS. The agreement between regulation compliance of chemical concentrations of effluent and observed toxicity from various biological toxicity tests was very poor to fair (kappa = 0.194~0.250). The data presented suggest that exposure to dyeing wastewater which were in compliance with Korean water quality standards may not be safe to aquatic biota, and multiple tropical levels should be considered in aquatic toxicity monitoring of dyeing industry.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.47-51
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• 2001

There are two strategies to cope with the troubles in landfill site after closure. The first method is active in a way that the wastes are dug up and the recyclable materials are reutilized, meanwhile the materials not recyclable are incinerated in order to minimize the volume of residues to be disposed of. The second method is rather passive and defensive in a way that the source of contamination, that is, buried wastes are not treated. Instead, the transport of leaking leachate and gases generated from the wastes are intercepted and controlled. In this study, as a passive way of the efficient leachate blocking process, applicabilities of geocrete and soluble sodium silicate as a substitute to control leachate leaking from landfill sidewall were investigated. In case of compression test, the strength of mixture I (Geocrete:Sodium silicate=1:3.9 v/v) and mixture II (Geocrete:Sodium silicate=1:2.5 v/v), even after 7 days' curing was higher than the minimum allowance to tolerate the loading(5 kg/$\textrm{cm}^2$). Soaking in the acid fur 4 days and 7 days respectively, the compressive strength of the specimens reduced seriously. The toxicity of geocrete is not detected through the bioassay test, once it was mixed with sodium silicate and the complex was formed. The hydraulic conductivity of the mixtures even after 7 days' curing was lower than the threshold limit $(1.0\times10_{-7}cm/s)$.