MONITORING OF LEACHATE QUALITY AT A SELECTED MUNICIPAL LANDFILL SITE IN PODLASIE, POLAND

The paper presents an evaluation of leachate monitoring data as well as investigation of temporal and seasonal variability of leachate quality. The analysis includes 27 sampling carried out at selected municipal landfill during 7-year observation period. In leachate samples, concentration of Pb, Cu, Zn, Cr, Hg, Cd, Total Organic Carbon (TOC), Polycyclic Aromatic Hydrocarbons (PAH) and value of pH and electro-conductivity (EC) were determined. Estimation of landfill leachate demonstrated a declining trend in EC, TOC and Zn concentration with time. Concentration of Pb, Hg, Cr, Cd and PAH remained relatively constant with respect to the sampling time, however, the value of pH showed a growing trend due to the decrease of the concentration of the partially ionized free volatile fatty acids. Average concentration of heavy metals in leachate were observed in trace quantities (<1.0 mg.dm(-3)). There were no statistically significant seasonal variations in concentration of the analyzed parameters, however, the highest concentration of EC, TOC and PAH were observed in summer. The negative correlation of pH with Pb, Cu, Zn, Cr, Hg, Cd indicated a strong connection of leachate's pH with heavy metals concentration. A cluster analysis allowed to specify two groups of variables: cluster I with TOC as an indicator of organic pollution in leachate and claster II with the rest of parameters. Further systematic monitoring is necessary, but its scope, according to the author, should be redefined.