Phosphorus recycled from pig manure and food industry effluents: experiences from bench to semi-industrial pilot scales

International audienceThe main sources for P recycling are animal manure and wastewater and the best way to close the loop is to produce a fertilizer which can substitute mineral fertilizers produced from ore. This can be achieved by producing products containing struvite (MgNH4PO4, 6H2O) and calcium phosphates as a form available for plants. In the both cases P crystallization is the key step of the process. The Phosph’OR project (2010-2014), funded by the French agency for research (ANR) gathered together four academic research institutes and four small enterprises to share and develop knowledge about P crystallization in the aim to design two recycling processes producing struvite or biological granules enriched with calcium phosphate, from high loaded organic effluents such as animal manure or food industries wastewater. The influence of mineral composition and organic matter on competition between struvite and calcium phosphates precipitation had been studied both in synthetic and real wastewater. A model allowing predicting the influence of process parameters on chemical reactions and kinetics is under development. Two lab scale and two semi-industrial scale pilots producing struvite and biological granules enriched with calcium phosphates identified as hydroxyapatite had been tested. The P efficiency of the recycled products compared to commercial triple superphosphate (CaH2PO4) and pure struvite and hydroxyapatite (Ca5(PO4)3OH) had been assessed by a pot experiment and soil incubations studies. The economic and environmental assessment of the processes (ACV) compared to reference scenarios of effluent management has been carried out. The purpose of this presentation is to give an overview of the most impacting and relevant results obtained during this collaborative research program