2026-09-24T12:43:04Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/129942 2025-10-25 col_2142_5131 col_2142_14770 com_2142_5130 com_2142_3518 com_2142_234

application/pdf en text Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-20 without embargo terms The student, Dong Hoon Sim, accepted the attached license on 2025-07-14 at 15:04. The student, Dong Hoon Sim, submitted this Thesis for approval on 2025-07-14 at 15:04. This Thesis was approved for publication on 2025-07-25 at 10:03. DSpace SAF Submission Ingestion Package generated from Vireo submission #22556 on 2025-10-20 at 20:15:14 Understanding the impact of chemical additives on struvite precipitation Sim, Dong Hoon 2025-07-25 Cusick, Roland D. Struvite Calcium Phosphate eng Although the use of struvite precipitation systems in water resource recovery facilities (WRRFs) is growing, these systems are frequently constrained by poor phosphorus recovery, fine particle losses, and inconsistent performance. Empirical precipitation models that overlook the impact of impurities and particle size on crystallization rates further limit reactor optimization. To comprehend the effects of supersaturation, organic additions (citrate and aspartate), and competing cations (calcium) on precipitation kinetics and particle dynamics, we conducted out a variety of struvite precipitation studies. Our findings demonstrate that supersaturation is important in particle dynamics in pure struvite growth solutions. After phosphorus removal stops, low supersaturation can extend the nucleation and growth phase before shifting to an aggregation dominating phase that continues to modify the particle size distribution. Citrate and aspartate experiments showed these additives promoted aggregation resulting in the formation of large (D > 500 µm) aggregates while also stabilizing smaller particles. The morphology of struvite changed from trapezoidal prisms to clusters of radially growing crystals that all emanated from a single central point when calcium was added. This observation is reinforced by the shift of the same peak to the right in the particle size distribution data, suggesting that struvite growth consistently centers around this nucleation point. Furthermore, amorphous calcium phosphate (ACP) starts to redissolve at around the 10-minute mark, according to calcium removal data, indicating that amorphous calcium that is not concentrated inside the struvite precipitants redissolve into the solution. 2025-08 Text https://hdl.handle.net/2142/129942 Copyright 2025 Dong Hoon Sim Civil & Environmental Eng Environ Engr in Civil Engr University of Illinois Urbana-Champaign M.S. Thesis