Phosphorus distribution in untreated and composted solid fractions from slurry separation.
Karin Jorgensen1, Jakob Magid, Jesper Luxhoi
1Dep. of Agriculture and Ecology, Faculty of Life Sciences, Univ. of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark. karinj@life.ku.dk
Journal of Environmental Quality
|January 6, 2010
Summary
Separation technology significantly impacts phosphorus content in slurry solids. Composting these solids conserves total phosphorus while modestly affecting bioavailability, maintaining fertilization quality.
Area of Science:
- Environmental Science
- Agricultural Science
- Waste Management
Background:
- Phosphorus (P) recovery from slurry is crucial for sustainable agriculture and nutrient management.
- Solid-liquid separation technologies influence the distribution and form of phosphorus in separated solids.
- Understanding phosphorus speciation is key to assessing its agricultural value and optimizing recovery processes.
Purpose of the Study:
- To analyze the distribution of different phosphorus fractions (water-soluble inorganic P [P(i)], acid-soluble P(i), residual P) in slurry solids obtained from various separation techniques.
- To compare the total phosphorus content and P fraction distribution across mechanical separation, flocculation-assisted separation, and anaerobic digestion-centrifugation.
- To evaluate the impact of composting on phosphorus distribution and bioavailability in separated slurry solids.
Main Methods:
- Collected 40 slurry solid samples from plants using mechanical separation, flocculation pre-treatment, or anaerobic digestion-centrifugation.
- Quantified water-soluble inorganic P, acid-soluble P(i), and residual P fractions.
- Determined total phosphorus (TP) content and P(i) to TP ratios.
- Composted three representative solid fractions for 30 days and analyzed P distribution before and after composting.
Main Results:
- Total phosphorus content varied significantly with separation technology, being lowest in mechanical separation (8-9 g P kg(-1) DM) and highest in anaerobic digestion-centrifugation (33.4 g P kg(-1) DM).
- Acid-soluble P(i) predominated in high-P solids; water-soluble P(i) was uncorrelated with TP but showed a higher proportion in mechanically separated solids.
- Composting conserved total P mass but generally decreased the proportion of water-soluble P(i), with modest changes in short- to medium-term P bioavailability.
Conclusions:
- Separation technology is a critical factor determining phosphorus concentration and speciation in slurry solids.
- Composting slurry solids is a viable option for storage and handling without significantly compromising their P fertilization potential.
- Further research could optimize composting parameters to enhance phosphorus bioavailability for agricultural applications.
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