USEPA LEAF methods for characterizing phosphorus and potentially toxic elements in raw and thermally treated sewage sludge

Biologically available phosphorus supports plant growth but can also cause environmental contamination. Sequential extraction methods, such as Hedley fractionation, are the most widely used to assess from solids. However, methods exhibit numerous deficiencies. The USEPA Leaching Environmental Assessment Framework (LEAF) is a tiered system developed evaluate releases of Potentially Toxic Elements (PTEs) This study compared fractionation method LEAF pH-dependent, parallel batch tests (Method 1313) and dynamic leaching column test 1314) bioavailability phosphorus. three were applied wastewater treatment sludge before after thermal treatment. Both revealed similar qualitative trends, namely that transformed into less immediately forms. inconsistent in forms amounts recovered left 40% unextracted 20% ash, suggesting it may be appropriate for organic materials. Moreover, only 2 6 pools within environmentally relevant pH conditions. Furthermore, overpredicted readily In contrast, allowed more detailed analysis availability - while simultaneously assessing PTEs across controlled range. simpler procedures provided easily interpreted results. Thus, facilitates robust valuable assessment inorganic solids being considered land application.