Leachates produced in a simulated landfill pilot plant were compared with those produced at the Zoreda landfill in Asturias, Spain. Three loads of different amounts of municipal solid waste (MSW) were added to the pilot plant at different stages, thus forming consecutive layers. Up to the present, approximately 3 333 000 t (metric tons) of MSW have been deposited in the landfill in 2.5 m high layers which are covered with soil from the surrounding area. The organic load of the leachates as COD decreased with time in both systems from very high initial values to relatively low ones by the end of the study, although they were higher in the actual landfill (approximately 4 g as opposed to 1.5 g O 2 dm-3 in the pilot plant). The pH decreased initially to values close to 6, but then increased to around 8. Ammoniacal-N (ammoniacal nitrogen) concentrations were high in both systems whereas metal concentrations were low.
Al-Yousfi, A.B., Pohland, F.G. & Vasuki, N.C. (1992) Design of landfill leachate recirculation systems based on flow characteristics. Proceedings of the 47th Industrial Waste Conference. Purdue University, Indiana, USA: pp. 491-500.
2.
Andreottola, G. & Cannas, P. (1992) Chemical and biological characteristics of landfill leachate. In: Christensen, T. H., Cossu R. & Stegman R. (eds) Landing of Waste Leachate. Elsevier Applied Science , pp. 65-87.
3.
Apha, Awwa & Wpcf (1989) Standard Methods for the Examination of Water and Wastewater. 17th, Ed. Washington, DC, USA: Public Health Association .
4.
Berrueta, J. & Castrillón, L. (1992) Anaerobic treatment of leachates in UASB reactors. Journal of Chemical Technology and Biotechnology54, 33-37.
5.
Castrillón, L. & Berrueta, J. (1991) Tratamiento anaerobio de lixiviados de vertederos de residuos sólidos urbanos (Anaerobic treatment of MSW landfill leachates) . Tecnología Del Agua77, 70-79.
6.
Clement, B. (1995) Physico-chemical characterization of 25 french landfill leachates. Proceedings Sardinia '95, 5th International Landfill Symposium. Cagliari, Italy: CISA, pp. 315-325.
7.
Contreras, A., Castrillón, L., Blanco, J. & Arcos, C. (1988) Caracterización analítica y tratamiento fisicoquímico de los lixiviados de dos vertederos de R.S.U. de diferente antigüedad (Analytical characterization and physico-chemical treatment of the leachates from two different aged MSW landills). Tecnología Del Agua42, 24-27.
8.
Ehrig, H.J. (1983) Quality and quantity of sanitary landfill leachate , Water Management and Research1, 53-68.
9.
Ehrig, H.J. (1996) Prediction of gas production from laboratory scale tests. Christensen, T. H., Cossu R. & Stegmann R. (eds) London, UK: E & FN Spon.
10.
Fernández, M., Martín, S., Sastre, H. & Marañón, E. (1995) Production potential of biogas in sanitary landfills. Proceedings Sardinia '95, 5th International Landfill SymposiumCagliari, Italy: CISA , pp. 629-634.
11.
Iglesias, J., Castrillón, L., Marañón, E. & Sastre, H. (1999) A study of the recirculation of landfill leachate in an MSW pilot plant. In: Anagnostopoulos, P. & Brebbia, C. (eds) Water Pollution, V: Modelling, Measuring Prediction. Southampton, UK: Witpress, pp. 57-66.
12.
Lema, J.M., Méndez, R. & Blázquez, R. (1988) Characteristics of landfill leachates and alternatives for their treatment. A review article. Water, Air and Soil Pollution40, 223-250.
13.
Martín, S., Marañón, E. & Sastre, H. (1997) Landfill gas extraction technology: study, simulation and manually controlled extraction. Bioresource Technology62, 47-54.
14.
Pohland, F.G. & Al-Yousfi, B. (1995) Design and operation of landfills for optimum stabilization and biogas production, Water Science Technology30(12), 117-124.
15.
Pohland, F., Cross, W. & King, L. (1993) Codisposal of disposable diapers with shredded municipal refuse in simulated landfills. Water Science Technology27(2), 209-223.
16.
Porcel, O., de Aguilar, F., León, J., Revilla, J. & Diz, J. (1994). Caracterización fisicoquímica de los residuos sólidos urbanos de la ciudad de Córdoba (Physico-chemical characterization of MSW from the city of Cordoba). Retema, Nov-Dec 1994, 66-71.
17.
Rodriguez, J. (1995) Digestión anaerobia de residuos sólidos urbanos en planta piloto. Trabajo de Investigación (Anaerobic digestion of MSW in a pilot plant). Research Paper. Oviedo, Asturias, Spain: Chemical Engineering and Environment Technology Department, University of Oviedo.
18.
Rodríguez-Iglesias, J., Castrillón, L., Marañón, E. & Sastre, H. (1998) Solid state anaerobic digestion of unsorted municipal solid waste in a pilot-plant scale digester. Bioresource Technology63, 29-35.
19.
Van der Broek, B., Lambropoulos, N.A. & Haggett, K. (1995) Bioreactor landfill research in Australia. Proceedings Sardinia '95, 5th International Landfill Symposium . Cagliari, Italy: CISA, pp. 183-192.
20.
Warith, M.A. (1999) Advantage of leachate recirculation on MSW biodegradation: experimental and field results. In: Anagnostopoulos, P. & Brebbia, C. (eds) Water Pollution, V: Modelling, Measuring & Prediction. Southampton, UK: Witpress, pp. 207-215.
