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Phosphate recovery from greenhouse wastewater
1Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia, Canada.
Summary
Phosphate recovery from greenhouse wastewater is effective using precipitation. Hydroxyapatite was the main product, but magnesium ions reduced phosphate removal efficiency.
Area of Science:
- Environmental Science
- Chemical Engineering
- Water Treatment
Background:
- Greenhouse wastewaters contain significant phosphate levels.
- Phosphate discharge can cause eutrophication.
- Efficient phosphate recovery methods are needed.
Purpose of the Study:
- To investigate phosphate recovery from greenhouse wastewater using precipitation/crystallization.
- To identify the main precipitates formed.
- To assess the impact of magnesium on phosphate removal.
Main Methods:
- Precipitation/crystallization process applied to greenhouse wastewater.
- Analysis of precipitate composition (calcium, magnesium, phosphate, potassium).
- Evaluation of the effect of magnesium concentration and Ca:Mg molar ratio on phosphate removal.
Main Results:
- Over 90% phosphate removal achieved.
- Hydroxyapatite [Ca5(PO4)3OH] identified as the primary precipitate.
- Increased magnesium concentration decreased phosphate removal rates.
- Precipitate composition was influenced by the calcium to magnesium molar ratio.
- Potassium content in precipitates was unaffected by magnesium addition; K-struvite was not a major product.
Conclusions:
- Precipitation/crystallization is a suitable method for phosphate recovery from greenhouse wastewater.
- Magnesium ions negatively impact phosphate removal efficiency.
- Hydroxyapatite is the dominant product under the studied conditions.