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Recovering critical fertilisers such as phosphorus from sludge treatment

Type of organisation or company:

Vellezzo Bellini (PV) Lombardy Region

Language for original content:

Project elaborated in partnership: 
Submitted by: 
ICESP (Italian Circular Economy Stakeholder Platform)
Start/End date: 

Type of funding:


The Acqua&Sole company recovers organic matter and nutrients by regenerating resources from food industry waste.

Since 2016 their plant processes sludge and other organic waste from agri-food industry via thermophilic co-digestion. Anaerobic digestion and simultaneous extraction of ammonia produces at the end of the process:

  • digestate from waste
  • ammonium sulphate as a secondary raw material (REACH registered)
  • biogas.

Digestate fertilisation (as opposed to traditional chemical fertilisation) produces an organic substance, thus contributing to the improvement and preservation of soil structure, fertility, water retention and biodiversity.

regulatory uncertainty;
Main results: 

Phosphorus is a critical material in agriculture fertilisation, but global stocks are finite and depleting. In 2020, the use of around 120 000 tons of digestate allowed for the recovery of:

  • 900 tons of phosphorus,
  • 90 tons of potassium and
  • 950 tons of nitrogen.

In 2020, around 4 000 tons of carbon were added to agricultural soils. The industrial-scale plant verified the economic sustainability of the initiative, which appears to be profitable.