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A simple method to release polyphosphate from activated sludge for phosphorus reuse and recycling
Akio Kuroda1, Noboru Takiguchi, Takafumi Gotanda
1Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan. akuroda@hiroshima-u.ac.jp
Biotechnology and Bioengineering
|March 29, 2002
Summary
Heating activated sludge releases accumulated polyphosphate (polyP). Calcium chloride then precipitates most phosphorus, enabling phosphorus recovery from wastewater. This method aids enhanced biological phosphorus removal.
Area of Science:
- Environmental Science
- Biotechnology
- Chemical Engineering
Background:
- Enhanced biological phosphorus removal (EBPR) processes utilize activated sludge microorganisms to accumulate significant amounts of polyphosphate (polyP).
- Efficient recovery of phosphorus from wastewater is crucial for resource sustainability and environmental protection.
Purpose of the Study:
- To investigate a simple method for releasing and recovering polyphosphate (polyP) from activated sludge.
- To assess the potential of this method for phosphorus recovery in a reusable form from wastewater.
Main Methods:
- Activated sludge from EBPR processes was heated at 70°C for approximately 1 hour to release polyP.
- Calcium chloride (CaCl2) was added to the heated sludge to precipitate phosphorus.
- The composition of the resulting precipitate was analyzed.
Main Results:
- Heating activated sludge at 70°C released nearly all accumulated polyP, with chain lengths of 100–200 phosphate residues.
- Addition of CaCl2 precipitated approximately 75% of the total phosphorus without requiring pH adjustment.
- The calcium-phosphorus precipitate was richer in phosphorus and lower in calcium compared to natural phosphorite deposits.
Conclusions:
- A simple heat-treatment method effectively releases polyP from activated sludge.
- Subsequent CaCl2 precipitation allows for efficient phosphorus recovery.
- This integrated approach shows promise for recovering reusable phosphorus from wastewater, complementing EBPR processes.