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Laboratory-determined Phosphorus Flux from Lake Sediments as a Measure of Internal Phosphorus Loading
Published on: March 6, 2014
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Pilot-scale study for phosphorus recovery by sludge acidification and dewatering
Cejna Anna Quist-Jensen1, Lisbeth Wybrandt1, Hanne Løkkegaard2
1Department of Chemistry and Bioscience, Aalborg University, Aalborg Ø, Denmark.
Environmental Technology
|February 27, 2019
Summary
Phosphorus recovery from wastewater sludge is crucial for Denmark
Area of Science:
- Environmental Engineering
- Chemical Engineering
- Water Treatment Technologies
Background:
- Denmark aims for high phosphorus recovery rates from wastewater.
- Wastewater sludge contains significant amounts of phosphorus, necessitating efficient recovery methods.
- Acidification is explored as a method to enhance phosphorus extraction from sludge.
Purpose of the Study:
- To investigate phosphorus recovery from wastewater sludge via acidification and dewatering.
- To determine the optimal pH for phosphorus dissolution and recovery.
- To evaluate the impact of sludge type on phosphorus release and acid consumption.
Main Methods:
- Pilot-scale acidification and dewatering of sludge from three different wastewater treatment plants.
- Varying pH levels (2-4) were tested to optimize phosphorus dissolution.
- Analysis of phosphorus concentration, dry matter content, and acid consumption in sludge and filtrate.
Main Results:
- Optimal phosphorus extraction occurred at pH 3, dissolving up to 68% of phosphorus.
- Digested sludge yielded higher phosphorus release but required more acid due to CO2 stripping.
- Filtrate dry matter increased with decreasing pH; an additional separation step could remove half of it.
- Approximately 60% of total sludge phosphorus was recovered in the filtrate.
Conclusions:
- Acidification is a viable method for phosphorus recovery from wastewater sludge.
- Optimal pH for phosphorus dissolution is around 3, balancing release and acid consumption.
- Sludge type influences process efficiency, with digested sludge showing higher release but also higher acid demand.
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