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Updated: Jun 25, 2025
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Electrochemically and Bioelectrochemically Induced Ammonium Recovery
Published on: January 22, 2015
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Transmembrane Chemical Absorption Process for Recovering Ammonia as an Organic Fertilizer Using Citric Acid as the
Ricardo Reyes Alva1, Marius Mohr2, Susanne Zibek1,2
1Institute of Interfacial Process Engineering and Plasma Technology (IGVP), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart, Germany.
Membranes
|May 24, 2024
Summary
Citric acid shows potential as a trapping solution for ammonia recovery using membrane contactors, though less efficient than sulfuric acid. It offers reduced water vapor transport and lower operational costs for this environmental application.
Area of Science:
- Environmental Engineering
- Chemical Engineering
- Separation Processes
Background:
- Membrane contactors facilitate ammonia removal via transmembrane chemical absorption (TMCA).
- Strong inorganic acids, like sulfuric acid, are commonly used as trapping solutions in TMCA.
- Ammonia recovery from wastewater is crucial for environmental protection and resource utilization.
Purpose of the Study:
- To evaluate citric acid as a trapping solution for ammonia recovery from anaerobic digestor reject water using TMCA.
- To compare the performance of citric acid with sulfuric acid in a liquid-liquid membrane contactor configuration.
- To assess the impact of temperature and pH on ammonia recovery efficiency and operational costs.
Main Methods:
- Laboratory-scale experiments using membrane contactors in a liquid-liquid configuration.
- Testing citric acid and sulfuric acid as trapping solutions at varying temperatures (22°C, 40°C) and feed water pH (10, 10.5).
- Quantifying ammonia recovery rates and water vapor transport.
Main Results:
- Citric acid showed lower ammonia recovery rates (10.7-16.5 pp at pH 10, 5-10 pp at pH 10.5) compared to sulfuric acid.
- Water vapor transport was consistently lower with citric acid, being 5.7 times lower at pH 10 and 40°C.
- Estimated operational costs favored citric acid, but neither acid resulted in a profitable process under the studied conditions.
Conclusions:
- Citric acid is a viable alternative trapping solution for ammonia recovery in TMCA, offering reduced water vapor transport.
- While less efficient in ammonia capture than sulfuric acid, citric acid presents potential economic advantages for scaling up.
- Further optimization is needed to improve process profitability for ammonia recovery from anaerobic digestor reject water.
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