Towards effective phosphorus recycling from wastewater: quantity and quality
T H Muster1, G B Douglas, N Sherman
1CSIRO Materials Science & Engineering, Clayton South MDC, VIC 3169, Australia. tim.muster@csiro.au
Chemosphere
|March 5, 2013
Summary
This study explores phosphate precipitation from wastewater, identifying struvite as the most desirable product for recovery. It details conditions for forming various phosphate phases and optimizing cost-effective recovery.
Area of Science:
- Environmental Chemistry
- Materials Science
- Chemical Engineering
Background:
- Wastewater treatment often involves complex chemical systems.
- Recovering valuable resources like phosphate from wastewater is crucial for sustainability.
- Understanding precipitation behavior in multi-component systems is key for effective resource recovery.
Purpose of the Study:
- To investigate phosphate precipitation in the Mg-Ca-NH3-PO4 system using synthetic wastewater.
- To identify crystalline phases formed under varying Mg/Ca ratios and pH conditions.
- To compare experimental findings with thermodynamic predictions and guide cost-effective phosphorus recovery.
Main Methods:
- Precipitation experiments were conducted using artificial wastewater with controlled Mg/Ca ratios (0-100%) and pH (5-11).
- Identified crystalline phases using analytical techniques.
- Evaluated precipitate properties including purity, growth, dewatering, and removal efficiency.
- Analyzed cost-effectiveness of different magnesium and calcium sources.
Main Results:
- Seven crystalline phases were identified: struvite, hydroxylapatite, newberyite, brushite, merrilite/whitlockite, octocalcium phosphate, and monetite.
- Significant discrepancies were observed between experimentally formed phases and thermodynamic predictions.
- Struvite emerged as the most favorable precipitate due to its purity, recovery efficiency, and ammonia removal capabilities.
- Preliminary brushite precipitation can enhance subsequent struvite purity by reducing calcium content.
Conclusions:
- Experimental conditions significantly influence phosphate phase formation in Mg-Ca-NH3-PO4 systems.
- Struvite precipitation is a highly effective method for phosphate and ammonia recovery from wastewater.
- Optimizing Mg and Ca sources, considering cost and precipitate quality, is essential for viable phosphorus recovery strategies.
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