(728b) A High-Throughput Method for Analyzing Struvite Formation and Morphology: Exploring the Effect of Peptide Additives

Precipitation of struvite (MgNH₄PO₄*6H₂O), a slow-release fertilizer, provides a means of recycling phosphate from wastewater streams. Through the implementation of high throughput methods, many different precipitation parameters can be investigated at once. In this work, these reactions occur in small volumes (300 μL or less) in a 96 well plate over the course of 45 minutes. A high throughput platform allows for a minimal use of chemicals and a fast way to compare many reaction conditions. The formation of struvite was investigated by fitting absorbance at 600 nm over time to a first order model with induction time. The impact of peptide addition was assessed through this platform, determining the peptide causes significant changes in the yield parameter and formation constant – allowing for control of precipitation. The impact of struvite seed dosing was also investigated, highlighting the importance of system optimization when peptide is present. Composition of struvite was confirmed through Fourier-transform infrared spectroscopy (FTIR) while morphology and crystal size were analyzed through optical microscopy. Crystals were elongated when precipitated with the peptide present. Finally, the utility of the high-throughput platform was demonstrated with a 2⁵ full factorial design to capture the effects and interactions of: magnesium dose, mixing time, seed dose, pH, and temperature.