Poznań University of Technology and Aquanet S.A. teams consisting of Agnieszka Strykowska (PUT), Natalia Kolwicz (PUT), Wiktor Gielniak (PUT) and Kinga Jóźwiak (AQ) joined their forces and experience in joint research under WP2 task 2.3 (Integrated technology of nitrogen and phosphorus recovery).
At the turn of 2022 and 2023, two Research Campaigns were carried out in the laboratory of the Poznań University of Technology in cooperation with the Aquanet laboratory. The aim of the research was to determine the optimal conditions for struvite precipitation in order to remove and recover phosphorus and nitrogen from wastewater. The research medium was the effluent from the centrifugation of sludge from the WWTP for the Poznań agglomeration in Koziegłowy. Each Campaign lasted 4 research days and included testing the level of phosphate removal using two sources of magnesium (magnesium hydroxide Mg(OH)2 and magnesium chloride MgCl2) in different pH ranges and using different molar ratios of P-PO4 ions to Mg ions .
During the first Research Campaign (November 15 – December 8, 2022), three molar ratios of P-PO4:Mg were tested: 1.0 ; 2.2 and 4.0 for pH 8.5; 9.0; 9.5 and the variant without pH correction for magnesium hydroxide. The results of the first Campaign made it possible to adjust the process conditions for the needs of the next research series.
The second Research Campaign took place between January 19 and February 7, 2023. As in the first series, three P-PO4:Mg molar ratios were tested: 1.2 ; 1.7 and 2.2 for pH 8.5; 9.0; 9.5 and the variant without pH correction for magnesium hydroxide.
The Research Campaigns carried out allowed to determine the optimal conditions for struvite crystallization using both tested reagents. In addition, interesting phenomena were observed (different habit of struvite crystals obtained using different Mg sources and a significant impact of the retention time of the samples on the results of phosphate removal), which prompted the PUT and AQ team to conduct an additional test series under selected process conditions in order to confirm and document the results research.
The research results will be presented during the upcoming conference for young scientists YWP in Poznań in November 2023.
