Landfill mining: A case study on characterization of excavated waste

Landfilling has represented the dominant method for municipal solid waste (MSW) disposal during the recent decades. Therefore, the recovery of materials from landfills through landfill mining is proclaimed as an innovative method to address these challenges. The excavation, processing, treatment and recycling of deposited materials is mainly referred to the economic aspects and to the reduction of the re-landfilled fraction of the waste. The main objective of this work is to describe a case study of sampling and characterization of excavated waste of a potential landfill mining site in Peccioli - Pisa (Legoli Landfill). Approximately at 10 m depth, the samples were collected from two layers of waste of different ages (2001 and 2007). Manual sieving and sorting into different waste fractions was performed. All the fractions were characterized in terms of total solids and total volatile solids and Biochemical Methane Potential test. Anaerobic tests were performed to evaluate methane production coming from landfilled waste, in particular referring to the residual biodegradable fraction contained in the municipal waste. Results show that the composition of the two excavated waste analyzed are quite different due to the waste management system used in that years. This factor affects methane production that resulted respectively 115 Nm3 CH4/ton e 47 Nm3 CH4/ton for 2001 and 2007.