Nutrient recovery in bioelectrochemical systems

Phosphorus, nitrogen, and potassium are essential nutrients for plant cultivation, but their production and use are currently unsustainable. Notable quantities of nutrients used as fertilizers end up in human and livestock wastewaters, emerging as interesting point sources for nutrient recovery. The high nutrient and organic contents and electric conductivities of some wastewaters make nutrient recovery in bioelectrochemical systems possible. Different bioelectrochemical applications have been studied for recovering nutrients separately or together into liquid or solid products, reaching recovery efficiencies as high as 96%. Pure solid precipitates display highest nutrient contents with up to 18% (w/w) of phosphorus, whereas nitrogen is typically present at highest concentrations in liquid products at 2%-3% (w/w). The generated nutrient products have shown comparable fertilizer performance to commercial alternatives when all essential nutrients are present in the product and can be considered economically viable for urban use once their safety is confirmed in toxicity tests.