[Phosphorus removal and recovery from human urine with MAP crystallization]
Qing-liang Zhao1, Zhi-gang Liu, Wei Li
1State Key Laboratory of Urban Water Resources and Environment, School of Municipal & Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China. qlzhao@hit.edu.cn
Huan Jing Ke Xue= Huanjing Kexue
|February 14, 2008
Summary
This study demonstrates efficient recovery of phosphorus and nitrogen from human urine using magnesium chloride to form struvite (MAP). Optimal conditions achieved over 95% phosphorus recovery, yielding a valuable fertilizer precipitate.
Area of Science:
- Environmental Chemistry
- Waste Management
- Materials Science
Context:
- Human urine contains significant amounts of phosphate and nitrogen, posing disposal challenges.
- Struvite (magnesium ammonium phosphate, MAP) precipitation offers a method for nutrient recovery from wastewater.
- Optimizing MAP precipitation from urine is crucial for sustainable nutrient management.
Purpose:
- To investigate the simultaneous removal and recovery of phosphate and nitrogen from stale human urine.
- To determine the optimal operating parameters for MAP precipitation using MgCl2 x 6H2O.
- To characterize the chemical properties of the precipitated MAP products.
Summary:
- Jar tests using MgCl2 x 6H2O showed that a Mg/PO4(3-)-P molar ratio above 1.3:1 is critical for achieving >95% phosphorus recovery.
- Optimal reaction time (20 min), precipitation time (2.0 h), and mixing speed (120 r/min) were identified without pH control.
- Characterization (SEM, XRD, ICP) confirmed the precipitates were nearly pure struvite with high P, N, and Mg content, suitable for fertilizer use.
Impact:
- Provides an efficient method for recovering valuable nutrients (phosphorus and nitrogen) from human urine.
- Demonstrates the potential for producing struvite as a slow-release fertilizer, contributing to a circular economy.
- Offers a sustainable solution for urine management, reducing environmental pollution and resource depletion.
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