Enhanced NH Removal and Recovery from Wastewater Using Na-Zeolite-based Flow-Electrode Capacitive Deionization: Insight from Ion Transport Flux.

Environ Sci Technol

Shenzhen Engineering Research Laboratory for Sludge and Food Waste Treatment and Resource Recovery, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.

Published: June 2023

AI Article Synopsis

  • Flow-electrode capacitive deionization (FCDI) is an effective method for treating wastewater and recovering materials, using a low-cost Na-modified zeolite combined with conductive carbon black to enhance performance.
  • The Na-zeolite electrode significantly reduces NH concentrations in wastewater, outperforming conventional activated carbon due to its superior NH adsorption capacity.
  • The process results in an easy separation of nitrogen-rich zeolite for use as a soil conditioner, demonstrating the potential of this technology for both wastewater treatment and agricultural applications.

Article Abstract

Flow-electrode capacitive deionization (FCDI) is a promising electromembrane technology for wastewater treatment and materials recovery. In this study, we used low-cost Na-modified zeolite (Na-zeolite) to prepare a composite flow-electrode (FE) suspension with a small amount of highly conductive carbon black (CB) to remove and recover NH from synthetic and actual wastewater (200 mg-N/L). Compared with conventional activated carbon (AC), the Na-zeolite electrode exhibited a 56.2-88.5% decrease in liquid-phase NH concentration in the FE suspension due to its higher NH adsorption capacity (6.0 vs. 0.2 mg-N/g). The resulting enhancement of NH diffusion to the electrode chamber contributed to the improved performance of FCDI under both constant current (CC) and constant voltage (CV) conditions. The addition of CB to the FE suspension increased the conductivity and facilitated Na-zeolite charging for NH electrosorption, especially in CV mode. NH-rich zeolite can be easily separated by sedimentation from CB in the FE suspension, producing a soil conditioner with a high N-fertilizer content suitable for soil improvement and agricultural applications. Overall, our study demonstrates that the novel Na-zeolite-based FCDI can be developed as an effective wastewater treatment technology for both NH removal and recovery as a valuable fertilizer resource.

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Source
http://dx.doi.org/10.1021/acs.est.3c02286DOI Listing

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