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Yanggu, South Korea

Jung Y.,National Institute of Environmental Research | Ko H.,Korea Environmental Corporation | Jung B.,Dong - Eui University | Sung N.,Dong - A University
KSCE Journal of Civil Engineering | Year: 2011

This work focused primarily upon the effects of ultrasonic pretreatment of both single frequency and dual frequency ultrasonic on the characteristics of sewage sludge disintegration. Quantifications of individual single frequency ultrasonic effects, as well as those of combined dual frequency ultrasonic were determined. This study also investigated and discussed the effects of ultrasonic power density and ultrasonic time. The reported results showed that the sludge solubilization rates increased as the ultrasonic time and ultrasonic power density increased. In terms of the degree of disintegration, the SCOD/TCOD ratio, the SCOD extraction rates, and the solubilization rates, dual-frequency ultrasonic at 28+40 kHz was more effective than single-frequency ultrasonic at 28 kHz or 40 kHz. Sewage treatment plants facing problems with the treatment and disposal of sludge can benefit significantly from the application of dual frequency ultrasonic to the process of sludge pretreatment. © 2011 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg. Source

Cho C.,Korea Environmental Corporation | Park S.,Pukyong National University | Sung K.,Pukyong National University
Vadose Zone Journal | Year: 2013

Although natural attenuation and phytoremediation can be cost-effective alternatives for the remediation of soils contaminated with volatile organic compounds (VOC), the risk of groundwater and plant contamination during the remediation process cannot be disregarded. In this study, the potential for subsurface contamination during natural attenuation as well as for plant contamination and recovery during phytoremediation in soils contaminated with 1,1,1-trichloroethane (TCA), trichloroethylene (TCE), and tetrachloroethylene (PCE) were investigated using a total of 56 polyvinyl chloride (PVC) columns filled with soil freshly contaminated by TCA, TCE, and PCE. Contaminant concentrations of soil gas, leachate, plant roots and shoots, and soil microbial biomass were monitored. The impact of easily degradable microbial substrate addition during natural attenuation on subsurface contamination was also examined. The results showed that VOCs migrated into deep soil or groundwater during natural attenuation and phytoremediation, and hence, the manner in which a site is initially managed is important for the eff ective application of natural attenua tion and phytoremediation of VOC-contaminated soil. In addition, the use of plant species that are fast growing under local environmental conditions was an effective technique for reducing the release of VOC into deep soil. The addition of substrate during natural attenuation helped to reduce subsurface contamination for all three VOC-contaminated soil systems, particularly PCE. The VOC were first detected in root and then in shoot samples as the experiment progressed. The VOC in plant shoots, unlike those in roots, still remained atter the soil was cleaned. Thus, careful plant management should be considered during VOC phytoremediation. © Soil Science Society of America 5585 Guilford Rd., Madison, WI 53711 USA. All rights reserved. Source

Shin S.K.,National Institute of Environmental Research | Jin G.Z.,National Health Research Institute | Kim W.I.,National Institute of Environmental Research | Kim B.H.,Ministry of Environment | And 3 more authors.
Chemosphere | Year: 2011

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) were measured in ambient air samples collected from different parts of South Korea in 2008, and the measured levels were used for assessing the spatial and temporal distribution of atmospheric PCDDFs and DL-PCBs in South Korea. The average concentrations of atmospheric PCDD/Fs and DL-PCBs among the 37 sites were 28fg I-TEQm-3 (ND∼617) and 1fg WHO-TEQm-3 (ND∼0.016). Elevated atmospheric levels of PCDD/Fs and DL-PCBs observed at residential/industrial sites and in the north-west of Korea, indicated a potential contribution and impacts of anthropogenic sources of PCDD/Fs and DL-PCBs. These levels were similar or lower than those previously reported in other ambient air surveys. Average concentrations of PCDD/Fs showed small seasonal variations (ANOVA analysis, p=0.144). The highest concentrations of PCDD/Fs were observed during winter, followed by spring, autumn and summer. Atmospheric PCDD/Fs and DL-PCBs in South Korea rapidly decreased during the last 10years (1998-2008), demonstrating the efficiency of stricter regulations and the application of best available technologies/best environmental practices at emission sources. Comparison of the congener profiles and principal component analysis showed that current atmospheric PCDD/Fs are mostly influenced by industrial sources and PCBs from old commercial PCB uses. Nationwide POPs monitoring will continue and allows an effective evaluation of the implementation of the Stockholm Convention on POPs. © 2011 Elsevier Ltd. Source

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