The paradigms of sustainability, the circular economy and the bioeconomy are a European priority for boosting competitiveness, creating jobs and generating sustainable growth. These approaches are particularly applicable to the management and treatment of wastewater and organic waste, including livestock manure. The European Commission has recently published a reference document on the Best Available Techniques (BAT) for the intensive rearing of poultry and pigs, which identifies the BAT for the treatment of pig slurry on farms, and describes struvite precipitation as an interesting emerging treatment. The document also states that there is still a lack of knowledge and successful experiences in situ for it to be considered a consolidated technology. Similarly, the Government of Catalonia does not consider the precipitation of K-struvite a consolidated method for the treatment of livestock manure. As a result, the situation described within the framework of this project is an opportunity to develop an innovative treatment that will require the definition of specific guidelines for application in the livestock farming sector. The project will boost the implementation of a slurry treatment system aimed at nutrient recovery.

This project seeks to develop a recovery process for a little-studied mineral, potassium struvite, in pig slurry treatment, in order to enable the recovery of nutrients (P and K) and its subsequent valorisation as a slow release fertiliser for agriculture, based on the concepts of environmental sustainability, the circular economy and the bioeconomy.

The actions in the project focus on three main areas: – Conceptual analysis of an NDN treatment plant for slurry and diagnosis of the interest in recovering Kstruvite. – K-struvite precipitation laboratory and prototyping tests. – Design and installation of a pilot facility for obtaining K-struvite. – Valorisation study of recovered products at a laboratory scale and under field conditions.

The following results are expected from the project:

– The construction and operation of an operational prototype under field conditions in order to obtain the new fertiliser, with recovery of the water fraction obtained.

– Obtaining of a new fertiliser with commercial appeal, which provides an equimolar mixture of nutrients (P, K, Mg), and is efficient from an agronomic point of view, and which also offers a satisfactory response to the need to manage NDN effluent from an environmental point of view.