Integration of liquid-liquid membrane contactors and electrodialysis for ammonium recovery and concentration as a liquid fertilizer. (April 2020)

• Record Type: Journal Article
• Authors: Vecino, X.; Reig, M.; Gibert, O.; Valderrama, C.; Cortina, J.L.
• Is Part Of: Chemosphere. Volume 245(2020)
• Publication Date: 2020-04
• Subjects: Ammonia valorisation -- LLMC -- ED -- Nutrient recovery -- Ammonium salts; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.125606
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The accumulation of ammonia in water bodies can cause eutrophication and reduce water quality. Furthermore, 80% of the ammonia in the world is consumed as fertilizer, which makes it a resource that can be recovered under the circular economy concept. Then, ammonia from wastewater can be valorised for agricultural applications. Liquid-liquid membrane contactors (LLMCs) have been postulated as a novel and eco-friendly technology for ammonia recovery, because they can convert dissolved ammonia into ammonium salts by an acid stripping solution. The concentration of the ammonium salt produced is limited by the co-transport of water in LLMC. Further concentration by electrodialysis (ED) is presented as a solution to overcome this problem. In this work, ammonia streams with different initial ammonia concentrations (1.7–4.0 g/L) were treated by LLMCs to produce liquid ammonium salt fertilizers (as NH4 NO3 and NH4 H2 PO4 ). Then, these ammonium solutions were concentrated by ED in order to achieve the nitrogen content required for direct application in agriculture for fertigation. After the LLMC process, the fertilizer obtained was composed of approximately 5.1% or 10.1% (w/w) nitrogen, depending on the initial ammonia concentration. After that, it was possible to concentrate these ammonium salts by a factor of 1.6 ± 0.3 using ED with an optimal energy consumption of 0.21 ± 0.08 kWh/kg ammonium salt and 93.1 ± 4.2% of faradaic yield. This gave a liquid fertilizer composed of 15.6% (w/w) nitrogen as NH4 NO3 . Overall, it was possible to integrate two innovative membrane technologies for the valorisation and concentration of nutrients from ammonia wastewater streams. Graphical abstract: Image 1 Highlights: Ammonia is a non-environmental friendly specie since it could cause eutrophication. LLMC can convert ammonia into ammonium salts by using an acid stripping solution. Ammonium salts can be used as liquid fertilizers due to its N content. Ammonium salts were concentrated by ED to achieve N fertilizers requirements. LLMC + ED integration was used to valorize and concentrate nutrients from wastewater.