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Published on: February 21, 2017
Phosphate fertilizer from sewage sludge ash (SSA)
1Eberhard Recycling AG, Steinackerstrasse 56, CH-8302 Kloten, Switzerland. markus.franz@eberhard.ch
Waste Management (New York, N.Y.)
|October 9, 2007
Summary
Sewage sludge ashes (SSA) can be processed into effective phosphate fertilizer, recovering over 90% of phosphorus. This method recycles a valuable nutrient, preventing its loss from biological cycles and creating a viable alternative to conventional fertilizers.
Area of Science:
- Environmental Chemistry
- Agricultural Science
- Waste Management
Background:
- Sewage sludge incineration ashes (SSA) contain significant phosphorus (4-9%).
- Current disposal methods remove phosphorus from biological cycling.
- Phosphorus is a critical plant nutrient essential for agriculture.
Purpose of the Study:
- To develop a three-stage processing method for SSA to recover phosphorus.
- To produce an adequate phosphate fertilizer from SSA.
- To evaluate the plant uptake efficiency of the fertilizer derived from SSA.
Main Methods:
- Leaching SSA with sulfuric acid to dissolve phosphorus.
- Purifying the leachate using ion exchange or sulfide precipitation to remove heavy metals.
- Precipitating phosphates as calcium phosphates and processing into a powdery fertilizer.
Main Results:
- Over 90% phosphorus extraction efficiency achieved.
- Ion exchange and sulfide precipitation effectively removed heavy metals (Cu, Ni, Cd).
- Fertilizer from SSA demonstrated equal plant uptake efficiency compared to conventional phosphate fertilizer in greenhouse trials.
Conclusions:
- A viable three-stage process exists for converting SSA into effective phosphate fertilizer.
- This method recovers valuable phosphorus, mitigating nutrient loss.
- Fertilizer from SSA is a sustainable alternative for agricultural applications.
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