This work was primarily funded by the Scientific and Technological Research Council of Turkey (TUBITAK) under grant no. 104Y378. We thank the support provided by the Kocaeli University Research Fund (2007/18 and 2007/47). The help of Dr. P. Kus and Dr. A. Karagunduz and the use of equipment at the Gebze Institute of Technology are appreciated. We especially thank to the authorities of the IZAYDAS Landfill for allowing the access to the site. The mention of trade names or commercial products does not constitute endorsement or recommendation for use