Kinetics based characterization of struvite dissolution

Aguiar, Samuel Enrique

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https://hdl.handle.net/2142/105729 Copy

Description

Title

Kinetics based characterization of struvite dissolution

Author(s)

Aguiar, Samuel Enrique

Issue Date

2019-07-19

Director of Research (if dissertation) or Advisor (if thesis)

Cusick, Roland D

Department of Study

Civil & Environmental Eng

Discipline

Environ Engr in Civil Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Struvite
• dissolution
• dissolution rate constant
• shrinking object model
• Phosphorus recovery
• Ostara
• Pearl
• Nutrient Recovery

Abstract

As phosphorus removal and recovery has become the new standard of wastewater treatment new technologies have quickly been implemented to meet the task. The Ostara Pearl is a crystallizer technology well known in the field of struvite precipitation for plants equipped with enhanced biological phosphorus removal (EBPR). By feeding anaerobically digested EBPR sludge to the Pearl and dosing Mg, struvite precipitation is induced for high rates of P removal. However, one downfall of crystallizers is the generation of poorly characterized fine particulate matter during normal operation, which leave the reactor and disrupt EBPR efficacy. The main objective of this work was to characterize the dissolution of field grown struvite from an Ostara Pearl reactor. Dissolution rate constants between 0.94 and 2.61 mm/min were found for field grown struvite using the shrinking object model – a surface area dependent empirical kinetics-based dissolution model. Enhanced solubility of some field recovered struvite relative to reference struvite was also observed in short-term experiments leading to a need a deeper characterization of those samples. Long-term dissolution experiments, used to characterize the dissolution of any co-precipitants, found little Ca, Fe, and K content in field grown struvite. XRD and FTIR were used to identify any physical and chemical differences in field grown struvite samples which exhibited increased solubility compared to a reference struvite sample. Dittmarite (MgNH4PO4*H2O) and another unknown crystalline solid were found to potentially lead to enhanced solubility. The importance of characterizing plant specific struvite was noted when instances of enhanced solubility were seen in samples which exhibit distinct FTIR bands when comparing surface to internal spectra.

Graduation Semester

2019-08

Type of Resource

text

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http://hdl.handle.net/2142/105729

Copyright and License Information

Copyright 2019 Samuel Aguiar

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