225 Environmental Technology, Vol. 28. pp 225-234 © Selper Ltd., 2007 COUPLING OF ABIOTIC AND BIOTIC PARAMETERS TO EVALUATE PERFORMANCE OF COMBINING NATURAL LAGOONING AND USE OF TWO SAND FILTERS IN THE TREATMENT OF LANDFILL LEACHATES L. ALEYA* 1 , H. KHATTABI 1 , E. BELLE 2 , H. GRISEY 2 , J. MUDRY 2 AND J. MANIA 3 1 Laboratoire de Biologie Environnementale, Université de Franche-Comté, 1, Place Leclerc, 25030 Besançon cedex, France 2 Laboratoire de Géosciences, Université de Franche-Comté, 16, route de Gray, 25030 Besançon cedex, France 3 Département de Géotechnique et Génie civil, Ecole Universitaire D'Ingénieurs de Lille (EUDIL), 59655 Villeneuve d ’Ascq France (Received 4 January 2006; Accepted 2 October 2006) ABSTRACT A study in the Etueffont landfill, located in Belfort (France), was conducted to evaluate the performance of combining natural lagooning and use of two sand filters for treating leachates through the coupling estimation of several abiotic and biotic parameters. Two gravel filters were installed in the upstream of the first basin which communicates with the remaing 2, 3 and 4 basins. The distribution of physical-chemical (T, pH, Eh, EC, O 2 , SM, SO 4 2- , Cl - , Zn, Fe, Mg, Ni, Al, As, Ba, Cu, Sn, Zn, BOD, COD, KN, NH 4 + , NO 2 - ,TP, AOX: absorbable organic halides, VFA: volatile fatty acids, and atrazine) and biological (bacteria, protozoa, phytoplankton) parameters was assessed in the leachate entering in basin 1, and downstream of the filters. The results showed slight variations in the physical-chemical composition of the leachate between 1999 and 2000, most likely ascribed to the maturation of the landfill but a very significant removal of SM (suspended matter) by the sand filters. This, applied to the majority of the studied parameters. Thus, the sand filter treatment of the leachates combined with natural lagooning was efficient in the improvement of water clarification. Keywords: Landfill leachate, sand filters, metals, bacteria, protozoa, phytoplankton. INTRODUCTION Landfill leachate generated by the biodegradation of solid wastes migrates away from a landfill and may pollute ground as well as surface waters [1,2]. While landfilling is the most attractive option for waste disposal, it may be a source of large quantities of organic and inorganic matters and heavy metals [3,4]. In particular, heavy metals that accumulate in the body with long biological half-lives [5], have been shown to cause several health hazards [6,7]. Thus, understanding the mechanisms fueling leachate generation may be a clue to reduce efficiently their unfavourable impacts on the surrounding environments [8]. Furthermore, leachate composition has been shown from laboratory experiments [9, 10] and in situ [11] to be closely linked to climate, hydrology and waste-hiding techniques. The stabilization ponds, that are generally designed to treat only an average quality of the leachate, are commonly put under extreme pressure-induced organic matter overload. Therefore, the process of leachate treatment, when it is conceived must take into account ‘worse case scenario’, i.e., intense increase in the concentration of polluting compounds. In the Etueffont landfill (Belfort, France), leachate components are treated by 4 stabilization ponds. However, in periods of high concentrations of organic matter in the basins, this option of leachate treatment showed low performance as it seemed unable to fulfill european standards (ISO 14000) to discharge into the surface and ground waters [12]. This study aimed thus at improving the performance of leachate treatment by combining natural lagooning and use of two sand filters upstream from the first basin. The capability for removing metals and other pollutants, together with microbial populations, was assessed through the measurement of several abiotic (major elements, metals and organics AOX: absorbable organic halides, VFA: volatile fatty acids and atrazine) and biotic parameters (bacteria, protozoa and phytoplankton). MATERIALS AND METHODS Study Site The Etueffont municipal solid waste landfill was opened in 1974. It is located in the North-East of France