Submitted on: 21 September 2006.
Revised on: 21 December 2006.
Accepted on: 08 January 2007.
___________________Frontiers of Environmental Science & Engineering
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Submitted on: 02 April 2008.
Revised on: 24 June 2008.
Accepted on: 24 July 2008.
___________________Frontiers of Environmental Science & Engineering
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Submitted on: 24 October 2005.
Revised on: 20 December 2005.
Accepted on: 14 January 2006.
___________________Frontiers of Environmental Science & Engineering