Integrated facility-level framework enables practical phosphorus recovery under real-world constraints

Area of Science:

• Environmental Science
• Resource Management
• Chemical Engineering

Background:

• Phosphorus is a finite resource critical for global food security.
• Import-dependent regions face supply risks due to concentrated reserves and geopolitical issues.
• Municipal wastewater sludge is a potential domestic source of phosphorus, but large-scale recovery is hindered by practical uncertainties.

Purpose of the Study:

• To develop and apply an integrated, facility-level framework for assessing phosphorus recovery potential from wastewater sludge.
• To evaluate the impact of engineering and economic constraints on phosphorus recovery yields.
• To identify optimal recovery pathways and strategies for advancing circular phosphorus economies.

Main Methods:

• Developed an integrated framework connecting treatment scale, process configuration, phosphorus speciation, costs, and spatial distribution.
• Applied the framework to a nationwide dataset for Japan.
• Modeled theoretical versus practical phosphorus recovery under real-world constraints.

Main Results:

• Engineering constraints reduced theoretical phosphorus recovery by 34-63%.
• An integrated pathway combining decentralized aqueous-phase recovery and centralized ash leaching shows significant potential.
• Substantial contribution to national agricultural phosphorus supply targets is achievable.

Conclusions:

• Constraint-integrated modeling provides a transferable basis for evaluating phosphorus recovery pathways.
• Targeted incentives and coordinated spatial redistribution are necessary to address cost heterogeneity and realize recovery potential.
• This work supports the advancement of circular phosphorus economies in import-dependent regions.