SURFICIAL DISINFECTION OF ESCHERIACHIA
COLI-CONTAMINATED PLAYGROUND SOIL BY UV
IRRADIATION |
Jaeeun Kim1, Tong Soo Kim2, Shin Hyeong Cho2, Min Cho1, Jeyong Yoon1†, Patrick J. Shea3, and Byung-Taek Oh4 |
1School of Chemical and Biological Eng., College of Engineering, Seoul National University, San 56-1, Sillim-Dong, Gwanak-Gu, Seoul, 151-742, Korea 2Department of Malaria and Parasitic diseases, National Institute of Health, 194, Tongil-Lo, Eunpyung-Gu, Seoul, 122-701, Korea 3School of Natural Resources and Center for Environmental Toxicology, University of Nebraska-Lincoln, Lincoln, NE 68583-0915, USA 4Department of Environmental Sciences & Biotechnology, Hallym University, 39 Hallymdaehak-Gil, Chuncheon, Gangwon-Do, 200-702, Korea |
Corresponding Author:
Jeyong Yoon ,Tel: +82-2-880-8927, Fax: +82-2-876-8911, Email: jeyong@snu.ac.kr |
Received: January 7, 2006; Accepted: April 6, 2007. |
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ABSTRACT |
Abstract:The necessity of disinfecting playground soil is an important issue, because pathogenic protozoa,
bacteria, and parasite eggs remain viable for several months and can infect children. UV irradiation has been
used to decontaminate water but its effectiveness on soil is unclear. We determined the efficacy of UV
radiation for inactivation of an indicator bacteria, E. coli (strain ATCC 8739), on playground soil. While
99% inactivation of E. coli in the soil was readily achieved by UV radiation within 55 min at 0.4 mW
cm-2, complete inactivation was not achieved, even after prolonged treatment at 4 mW cm-2. This was
attributed to the irregular surface of the soil. A small number of E. coli escaped the UV radiation because
they were situated in indentations or under small particles on the soil surface. Atomic force microscopy
(AFM) and scanning electron microscopy (SEM) confirmed that the surface characteristics of the soil is the
major limiting factor in the inactivation of E. coli by UV radiation. Thus UV treatment may not be
adequate for disinfecting some soils and should be carefully evaluated before being used on playground soils. |
Keywords:
Disinfection | E. coli | Inactivation | Playground Soil | UV |
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