Project title
"Water treatment plants as resource hubs: enabling circularity by maximizing recovery of iron coagulants, phosphorus, silicate materials and others with the Sahara process"
Project leader
Hanna Landbring, EasyMining
Duration
220815-240815
Funding
The project is funded by the Swedish Energy Agency, Vinnova and Formas via the strategic innovation programme RE:Source.
Sahara Re:Source: Phosphorus and Iron Recovery
In the Sahara Re:Source project we demonstrate that our Ash2Phos add-on process can significantly improve the recovery of phosphorus, iron coagulants, and silicate sand from sewage sludge ash, contributing to circular material use.
As we shift towards a circular economy and strive to reduce greenhouse gas emissions, maximising the use of secondary materials, or waste, is essential. Phosphorus is a vital nutrient for all living organisms, primarily sourced from phosphate rock - a limited resource. In the EU, both phosphate rock and phosphorus are classified as critical raw materials. Many countries rely on imports, exposing them to market fluctuations and geopolitical risks.
To address this, recovering phosphorus from wastewater and sewage sludge is becoming increasingly important. Countries like Germany have already implemented legislation mandating phosphorus recovery. Additionally, sewage sludge contains significant amounts of iron from coagulants used in water treatment.
Sludge oxidation (e.g., incineration) generates ash that concentrates valuable substances like phosphorus and iron, but it also contains heavy metals, often leading to landfill disposal due to the lack of recycling technologies.
EasyMining has developed Ash2Phos, a wet-chemical process that efficiently recovers valuable elements from sludge ash. This innovative solution achieves around 90% phosphorus recovery while also extracting 15% of iron as ferric chloride coagulant. The process produces a silicate sand containing residual iron and phosphorus, which limits its applications.
To enhance recovery yields and eliminate unwanted iron, we introduced Sahara, an Ash2Phos add-on that effectively recovers iron as drinking water quality ferric chloride.
This makes the Ash2Phos-Sahara process a truly circular solution for coagulants, enabling the production of iron- and phosphorus-free silicate material with beneficial pozzolanic properties.
This project focused on improving the Sahara process, integrating it into Ash2Phos and preparing for the deployment in Europe.
Read more about the project in the latest press release
Partner/role
EasyMining
Coordinator, running the pilot and production of samples, market study and business case
Feralco and Sydvatten
Validation of the recycled ferric chloride
Thomas Concrete
Validation of recycled iron-depleted silicate material
Ragn-Sells and Imperial Collage London
Chemicals as a service concept for ferric chloride, workshops with stakeholders
IVL
Life cycle assessment