Representativeness of an automobile shredder residue sample for a verification analysis

To apply a decision-making scheme using a statistical classification while conforming to the meaning of representativeness as defined by the US EPA, we propose an equation defining the representativeness of a sample. To utilize this equation, the batch must be homogenized. This requires analyzing the constitution and distribution heterogeneities. The equation relates the sample weight m s to its representativeness R either by a statistical approach or by a physical approach using the following equation: m s = { 4 / ( 1 - R ) 2 } · [ K + k e ( 1 - 2 t e ) / t e ] . In the equation, K and k e are the heterogeneity factors determined from a descriptive analysis. This equation is applicable to solid waste with majority constituents such as automobile shredder residue (ASR) and domestic waste. This analysis was applied to a sample of ASR in the framework of a verification for France. The results of the analysis showed that the sample weight must be at least 140 kg to have a representativeness of 90%.