Project Portugal 2030

Summary

The main goal of this project is to foster, in a sustainable and economically viable way, critical nutrients/minerals recovery from sidestream digestate and brines by precipitation/crystallization able to: i) produce nutrient-based fertilizers to ensure food security and sustainable agriculture (SDG2) and partially help to reduce global warming by replacing synthetic fertilizers generated in energy-intensive processes involving fossil fuels and raw materials intensive processes (SDG 13); ii) minimize the environmental footprint of wastewater treatment through the reduced load of nutrients and reduced eutrophication (SDGs 6 and 7); iii) decrease the consumption of natural resources (mined phosphate rock) and save costs associated with N fixation (SGD 12); iv) decrease the EU dependence on raw materials (e.g. Mg, defined as one of the twenty critical raw materials (CRM) by the EU; v) reduce/avoid the discharge of brines into water bodies, reducing their environmental impact (SDG 14). To achieve these goals, a low footprint (< 2 m2) PILOT CRYSTALLIZER (TRL=6) based on an oscillatory flow crystallizer (OFC) [18,19] (Fig. 1) will be developed (technological progress in wastewater and brines treatments (SDG 9)), combining computational modelling and experimental studies. This cutting-edge technology will be able to promote, in a CONTINUOUS MODE, a MINIMUM OF 90% PHOSPHOROUS AND 40% AMMONIUM RECOVER (currently ~50% and 25%) IN THE FORM OF STRUVITE and/or HAP from the sidestream digestate with sufficient purity and physical characteristics, that can be separated easily from the wastewater and used as a FERTILIZER for industrial or agricultural applications. In addition, the innovative technology will also be able to RECOVER, SELECTIVELY, 100% of Mg and 98% of Ca with a purity above 95% (currently 80-90%) from brine to be used in different industrial sectors, including wastewater treatment plant. The continuous oscillatory flow crystallizer will be initially optimized in terms of feeding scheme to the network, superficial liquid velocity (mixing energy), oscillatory conditions (frequency and amplitude), reactants’ type and dose, temperature, pH and sidestream digestate constituents. Low-cost sources of Mg/Ca salts, such as nanofiltration / reverse osmosis concentrate from seawater desalination, will be evaluated to significantly reduce the cost of producing struvite and/or HAP. For that, in parallel (please see the timeline), Mg/Ca will be precipitated selectively using similar approaches. Based on computational modeling and the experimental results obtained at lab-scale an optimized system will be built and validated experimentally at a pilot-scale (1 m3/h (struvite/HAP) and 90 L/h (Mg/Ca)) with the collaboration of EFACEC, AdP, A´guas e Energia do Porto and Renewable Energies Chair at the University of Évora. The expected pilot plant will be a disruptive technology in brine and wastewater treatment in contrast with the standard technologies [9,15–17,20], being characterized by its size (footprint < 2 m2), mixing efficiency (subproduct reduction), production flexibility (operation in a continuous mode), low reagents consumption, and operation costs reduction.