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Updated: Jun 19, 2026
09:05
Supercritical Nitrogen Processing for the Purification of Reactive Porous Materials
Published on: May 15, 2015
Chemical precipitation for controlling nitrogen loss during composting
Li-Mei Ren1, Guo-Xue Li, Yun-Jun Shen
1College of Resource and Environmental Science, China Agricultural University, Beijing 100193, China.
Summary
Adding magnesium hydroxide and phosphoric acid to compost significantly reduces nitrogen loss by forming struvite, improving compost quality and maturity. This method enhances nutrient content and accelerates organic matter degradation.
Area of Science:
- Environmental Science
- Soil Science
- Waste Management
Background:
- Nitrogen loss is a significant challenge during composting, reducing fertilizer value and causing environmental issues.
- Magnesium hydroxide and phosphoric acid offer a potential solution to mitigate nitrogen volatilization.
Purpose of the Study:
- To evaluate the efficacy of magnesium hydroxide and phosphoric acid additives in controlling nitrogen loss during composting.
- To compare the effects of ex situ and in situ application methods on compost quality and nutrient content.
Main Methods:
- Two composting trials (TA - ex situ, TB - in situ) were conducted using magnesium hydroxide and phosphoric acid (1:2 molar ratio) as additives.
- Key parameters including temperature, pH, TOC, TN, NH4(+)-N, TP, AP, and germination index were monitored over 26 days.
- X-ray diffraction was used to analyze precipitation products.
Main Results:
- In situ application (TB) significantly improved ammonium nitrogen (NH4(+)-N) and total nitrogen (TN) compared to the unamended control (TA).
- Compost amended in situ (TB) showed higher maturity (102% germination index) than the control (82%).
- Struvite (magnesium ammonium phosphate) precipitation was identified in the in situ amended compost, indicating ammonia capture.
Conclusions:
- The combination of magnesium hydroxide and phosphoric acid effectively reduces ammonia emission through struvite crystallization.
- In situ application of these additives enhances compost quality, nutrient content, and maturity.
- Further research is needed to optimize struvite precipitation conditions for different composting systems.
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