Removing phosphate CIWI

It’s in-depth Tuesday and this time we will focus on phosphate: the determining factor in the future of wastewater treatment.

The new Urban Wastewater Treatment Directive sets tighter phosphate limits. Biological P removal is reaching its limits. Not because it fails, but because stability and control at very low concentrations are constrained.

At the same time, closing the phosphate cycle is becoming urgent. Current removal fixes phosphate in sludge: it meets standards but makes high-quality recovery difficult. The stricter the standard, the more we lose a finite and essential resource.

STOWA recognizes this tension. Future treatment plants will rely less on biology and more on chemical and physical processes for phosphate removal. The key question becomes: which chemistry supports a circular phosphate strategy? Innovations like phosphate recovery as vivianite show removal and recovery can go hand in hand. Phosphate is treated as a resource, not a waste stream.

This aligns with CIWI’s vision: moving from externally produced metal salts to on-site, tailored chemistry, designed with phosphate recovery in mind.

The future of phosphate removal is not just lower concentrations, it’s smarter system choices. Taking phosphate seriously means looking beyond compliance. That’s why we choose chemistry over chemicals. 

The photo shows our self-produced sustainable additive that can remove phosphate. In the recognizable orange color that is created during the process.