Influence of pH and Temperature on Struvite Purity and Recovery from Anaerobic Digestate

Carolina González-Morales, Belén Fernández, Francisco J. Molina, Darío Naranjo-Fernández, Adriana Matamoros-Veloza and Miller Alonso Camargo-Valero
Additional contact information
Carolina González-Morales: Grupo GAIA, Escuela Ambiental, Facultad de Ingenieria, Universidad de Antioquia, Medellin 050010, Colombia
Belén Fernández: IRTA–GIRO Program, Institute of Agrifood Research and Technology, 08001 Barcelona, Spain
Francisco J. Molina: Grupo GAIA, Escuela Ambiental, Facultad de Ingenieria, Universidad de Antioquia, Medellin 050010, Colombia
Darío Naranjo-Fernández: Grupo GAIA, Escuela Ambiental, Facultad de Ingenieria, Universidad de Antioquia, Medellin 050010, Colombia
Adriana Matamoros-Veloza: Institute of Functional Surfaces, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK
Miller Alonso Camargo-Valero: BioResource Systems Research Group, School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK

Sustainability, 2021, vol. 13, issue 19, 1-14

Abstract: The precipitation of struvite (MgNH 4 PO 4 .6H 2 O) from wastewater streams simultaneosuly recovers nitrogen (N) and phosphorus (P) for reuse as fertilisers. Struvite crystallisation is controlled by pH, saturation index, temperature and other ions in the solution (e.g., Ca 2+ , Mg 2+ and CO 3 2− ). This work studies the effect of pH and temperature on phosphorus and nitrogen removal via struvite precipitation and the quality of the resulting precipitate product (i.e., crystal size, morphology and purity). Struvite was precipitated in batch reactors from the supernatant produced during anaerobic sludge dewatering at a wastewater treatment works, under controlled pH (8, 9 and 10) and temperature (25, 33 and 40 °C) conditions. The optimal P removal as struvite, reduction of the co-precipitation with Ca and the increase in particle size of the struvite precipitates were determined. The results showed that temperatures of 33 °C and 40 °C are not recommended for struvite precipitation—i.e., at 33 °C the purity is lower, and at 40 °C the ammonia losses are induced by volatilisation. At all pH-tests, the P removal efficiency was >93%, but the highest phosphate content and purity as struvite were obtained at a pH of 9.0. The optimum pH and temperature for the formation of large crystals (84 µm) and a high purity (>70%) of the struvite precipitates were 9 and 25 °C, respectively.

Keywords: centrate; nutrient recovery; saturation index; struvite crystallisation; sustainable sanitation (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (5)

Downloads: (external link)
https://www.mdpi.com/2071-1050/13/19/10730/pdf (application/pdf)
https://www.mdpi.com/2071-1050/13/19/10730/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jsusta:v:13:y:2021:i:19:p:10730-:d:644236

Access Statistics for this article

Sustainability is currently edited by Ms. Alexandra Wu

More articles in Sustainability from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().