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Nitrogen loss during solar drying of biosolids
S A O'Shaughnessy1, I Song, J F Artiola
1USDA-ARS, Conservation and Production Laboratory, P O Drawer 10, Bushland, TX 79012, USA.
Environmental Technology
|July 10, 2008
Summary
Solar drying of biosolids leads to nitrogen loss, primarily through ammonia volatilization. Tillage and drying season significantly impact these nitrogen fertilizer losses.
Area of Science:
- Environmental Science
- Agricultural Engineering
- Soil Science
Background:
- Biosolids are a valuable nitrogen-rich fertilizer source, commonly dewatered by solar drying for easier transport and pathogen reduction.
- Understanding nitrogen dynamics during solar drying is crucial for optimizing biosolids land application as fertilizer.
Purpose of the Study:
- To investigate nitrogen loss during solar drying of biosolids, comparing tilled and untilled samples.
- To analyze the concentrations of nitrate (NO3-) and ammonium (NH4+) ions in biosolids during solar drying.
Main Methods:
- Conducted three solar drying experiments using aerobically and anaerobically digested biosolids.
- Analyzed biosolid samples for nitrate (NO3-) and ammonium (NH4+) ion concentrations.
- Evaluated the effects of tillage and solar drying season on nitrogen content.
Main Results:
- Nitrogen losses varied significantly based on the solar drying season and whether the biosolids were tilled.
- Ammonia volatilization was identified as the primary pathway for nitrogen loss, though not directly measured.
- Organic nitrogen content remained stable, nitrate levels were mostly undetectable, and ammonium-nitrogen decline correlated with moisture loss.
Conclusions:
- Solar drying can lead to substantial nitrogen loss from biosolids, primarily via ammonia volatilization.
- Tillage practices and seasonal conditions influence the extent of nitrogen loss during biosolid solar drying.
- Further research is needed to quantify ammonia volatilization and develop strategies to mitigate nitrogen loss.
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