Environmental Trade-Offs in Phosphorus Recovery: A Comparative LCA of Pyrolysis and Hydrothermal Carbonization of Poultry Manure

Phosphorus is a non-renewable resource critical for global food security, yet its natural reserves are rapidly depleting. Meanwhile, the poultry industry generates vast amounts of nutrient-rich waste that pose serious environmental risks if not managed properly. While valorizing these wastes offers a sustainable raw material alternative, investigating the environmental impacts of recovering them as a phosphorus source is crucial. This study evaluates phosphorus recovery from poultry litter via acid leaching following Hydrothermal Carbonization (HTC) and pyrolysis processes holistically. By conducting a Life Cycle Assessment (LCA) using this specific substrate and method combination, this work aims to provide comprehensive environmental insights. The impact assessment reveals that the total Global Warming Potential (GWP) is 6.00 kg CO2 eq for the pyrolysis scenario and 4.18 kg CO2 eq for the HTC scenario. Methodologically, a ‘system expansion’ approach was applied to integrate the avoided burdens from poultry manure management into the system boundaries. Furthermore, the inventory analysis revealed that chemical consumption (specifically NaOH and H2SO4) in the production process is the dominant factor not only for Global Warming Potential (GWP) but also across other environmental impact categories evaluated. The findings clearly indicate that chemical intensity predominantly determines the environmental performance across carbon footprint, acidification and other environmental impact categories.