Long term stabilization in a dry tomb landfill

The organic biodegradable fraction is one of the most hazardous Msw which can be landfilled; then, the dry tomb landfilling technology shifts the risk problem to the end of the aftercare period (the landfill regulation in Europe currently sets this period in 30 years), when the efficiency of environmental protection devices will be reduced and the landfill will be a contaminated site, no longer financed by a waste fee. Two questions arise from these issues: firstly, how is it possible to decrease, in a sustainable way, the risk factor of the residual humid fraction before landfilling or directly in the landfill? Secondly, how long should the aftercare period be? A sustainable way to manage the biodegradable organic fraction of Msw cannot neglect the goal to reduce the hazardousness of waste before its disposal in the landfill where it could be right to carry out management procedures aimed at accelerating the complete stabilization of waste and reaching acceptable levels of environmental impact in short and defined time. Even though, at present, no European directive regulates the bio-waste biological treatment, many Italian regions have equipped themselves, on a local level, with appropriate legal powers enabling them to achieve such a treatment. However, both the protocols for plant planning and management and those related to the quality control of the treated material are still in need of definition and experimentation. In Puglia region, a regional law, the n. 296/2002, defines plant technical aspects and fixes the limits for the dynamic respiration index value of the Msw that must be landfilled. In particular, according to the local planning regulations controlling integrated management systems, all Msw must be introduced into the biological treatment plant – and not only the under-sieve - and before being disposed of in the landfill, dynamic respiration index must be lower than 800 mgO2/kgvss*h. This paper shows the preliminary results of a more complete study about the assessment of residual biodegradability of landfilled waste after approximately 15 years in the dry-tomb landfill of Giovinazzo – near Bari, in the South of Italy – obtained by using dynamic respirometric techniques.