Concentrating nitrogen waste with electrodialysis for fertilizer production

18 July 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Recovery of nitrogen from wastewater presents a unique opportunity to valorize waste and contribute to a more circular nitrogen economy. However, dilute solution separations are challenging for most state-of-the-art separations technologies. This often results in technologies having low concentration factors that result in low-value products (e.g. < 1 wt\% N). Here, we demonstrate how a cascading electrodialysis system combined with a hollow fiber membrane contactor (ED+HFMC) system can achieve efficient recovery of ammonia from simulated centralized animal feeding operations (CAFO) wastewater. The integrated system achieved an overall concentration factor of ~200x (~ 40 x in ED and a further ~5x in HFMC) and produced a ~10 wt\% NH4-N fertilizer product. The specific energy consumption (SEC) for the three stages of the ED was 1.89--6.14 kWh/kg NH4-N, which is significantly lower than the Haber--Bosch process (8.9--19.3 kWh/kg N). Operating costs were calculated to be <50 ¢/ kg NH4+-N for each of the ED stages and NH_3 stripping. This integrated ED+HFMC system holds promise for the recovery of ammonia from wastewater as it achieves high concentration factors and has low energy demand.

Keywords

Ammonia recovery
nutrient recovery
waste valorization

Supplementary materials

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