Evaluation of the quality and treatability of leachate produced at a landfill connected to an urban waste composting and recovery plant at Alhendin (Granada, Spain)

The leachate produced at a landfill adjoining an urban waste composting and recovery plant at Alhendin (Granada, Spain) was sampled for a period of more than 3 years from February 2003 until July 2006. The main pollutant parameters (COD, BOD(5), solids, nitrogen, main anions and cations, pH, Eh and conductivity) were analysed with the aim of selecting the most effective treatment for the leachate. The results obtained showed high concentrations of different pollutants with COD and BOD(5) values up to 74,133 mg/L and 39,000 mg/L respectively. Seasonal changes in leachate composition were mainly attributed to differences in rainfall, temperatures, and evaporation rates. Our study classified the Alhendin landfill leachate as a partially stabilized leachate because of: (i) its management strategies (storage at artificial ponds and recirculation); (ii) the coexistence in the landfill of active and closed cells with wastes of different ages and at different decomposition phases. The leachate quality data obtained was statistically evaluated using various statistical tools. A good correlation was found between many of the parameters analysed, some of which also showed good linear regressions. Principal component analysis allowed the reduction of most of the parameters analysed to four components: Component 1 (K(+), Mg(2+), FTS, VDS, VTS, Na(+) and Cl(-)), component 2 (BOD(5)), component 3 (TDS, TS, FDS and conductivity) and component 4 (pH, FSS, Eh and VSS). The results obtained are valuable for the selection of the best leachate treatment option. A combination of a physicochemical treatment and a fixed film biological system is recommended for this leachate.