The Effect of the Elemental Composition of Municipal Sewage Sludge on the Phosphorus Recycling during Pyrolysis, with a Focus on the Char Chemistry—Modeling and Experiments

The present study investigates how the original sewage sludge characteristics influence composition of sludge-based chars for land applications. Sewage from two different wastewater treatment plants in Sweden was pyrolyzed at 500, 700, and 900 °C, resulting were analyzed. Thermodynamic equilibrium calculations (TEC), together with chemical fractionation, implemented to simulate char after pyrolysis process temperatures. results showed that, general, both municipal (MSS), phosphorus (P) significantly retained various However, no specific correlation could be found between temperature amount P remaining. With regard heavy metals removed reaction, concentrations copper, chromium, lead, nickel, zinc, cadmium below limits Swedish regulations farmland application.