Electrochemical Precipitation of Struvite from Wastewater: A Sustainable Approach for Nitrogen Recovery

Abstract

This study evaluates the feasibility of nitrogen recovery from wastewater via electrochemical methods as an alternative nutrient source for agricultural applications. Ammonium nitrogen (NH4+-N) and phosphate (PO43−-P) contamination poses significant environmental risks and challenges water resource management globally. The electrochemical precipitation of struvite (MgNH4PO4·6H2O) offers a promising solution for nutrient recovery, with potential applications as a slow-release fertilizer. Experimental results demonstrate that increased current density (from 2.5 to 7.5 mA/cm2) and reduced electrode distance (1 cm) significantly enhance NH4+ and PO43− consumption and struvite precipitation. Increasing the amperage from 2.5 to 7.5 mA·cm−2 at a 1 cm electrode distance raised the ammoniacal nitrogen incorporation from 1.59 to 5.34 g/100 g, signifying greater struvite production. The Mg and P concentrations were 15.44 and 12.60 g/100 g, respectively, for this higher amperage, although lower than the concentrations seen with 2.5 mA·cm−2 (22.16 and 14.52 g/100 g). The majority of Mg (60%) and P (93.6%) were, however, incorporated within struvite. Additionally, this study reveals that Mg is primarily incorporated as struvite when using higher current densities, while lower current densities yield greater Mg incorporation in non-struvite forms, such as magnesium carbonate. Findings suggest that optimizing current density and electrode distance can improve nitrogen and phosphorus recovery efficiencies, making electrochemical struvite production a viable, sustainable approach for nutrient recycling. This method not only reduces dependence on synthetic fertilizers but also supports sustainable agricultural practices by transforming wastewater contaminants into valuable resources.