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Calcium Carbonate Formation in the Presence of Biopolymeric Additives
Published on: May 14, 2019
Carbonate and magnesium interactive effect on calcium phosphate precipitation
1Soil and Water Science Department, University of Florida, Gainesville, Florida 32611, USA.
Environmental Science & Technology
|February 21, 2008
Summary
Carbonate and magnesium ions significantly impact calcium phosphate precipitation in soils and wastewater. Their combined presence can either synergistically inhibit or, under specific conditions, enhance precipitation by altering mineral formation and reaction rates.
Area of Science:
- Environmental Chemistry
- Soil Science
- Water Treatment
Background:
- Calcium phosphate precipitation is crucial for phosphorus management in agricultural soils and wastewater.
- Understanding factors influencing precipitation is key to optimizing phosphorus use and recovery.
Purpose of the Study:
- To investigate the interactive effects of carbonate (CO3(2-)) and magnesium (Mg2+) on calcium phosphate precipitation.
- To simulate conditions relevant to dairy manure-amended soil leachate and wastewater phosphorus recovery.
Main Methods:
- Precipitation experiments were conducted under two distinct pH conditions (7.1 and 9.2) simulating soil leachate and wastewater.
- Analyzed the impact of individual and combined carbonate and magnesium on precipitate composition, crystallinity, and formation rates.
Main Results:
- Carbonate reduced precipitation rates by competing with phosphate or promoting calcium carbonate formation.
- Magnesium severely inhibited precipitate crystallinity and rate, leading to amorphous calcium phosphate formation.
- Synergistic inhibition occurred in soil leachate conditions, while in wastewater, combined ions enhanced precipitation by forming aqueous magnesium carbonate complexes.
Conclusions:
- The interactive effects of carbonate and magnesium are complex and highly dependent on solution chemistry and pH.
- These findings offer insights into managing phosphorus stability in soils and improving phosphorus recovery efficiency from wastewater.
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