Changes in the quality of landfill leachates from recent and aged municipal solid waste.

A leachate study was conducted at the Etueffont landfill (Belfort, France), to examine differences in leachate composition between old and new areas of the fill and their seasonal evolution. It was based on hourly (1999), monthly (1998-1999) and annual (1993 to 1998) samplings of domestic landfill leachate. Variations in flow rate, rainfall, temperature, electrical conductivity, O2, pH, Cl, SO4, Zn, Cu, Fe, Ni, HCO3, NO3, NH4, BOD and COD were monitored. The results from monthly samplings showed close coupling between flow and concentrations of all parameters measured in the leachate. Indeed, these latter parameters decreased with increasing flow rates. Also, mass emissions per unit waste mass decreased with increasing waste age. The hourly monitoring pointed out an increase in electrical conductivity, chloride and COD concentrations in the middle of the day. This was most likely attributable to temperature fluctuations.