Urine source separation: a promising wastewater management option

Nutrients have to be removed by resource-intensive processes at wastewater treatment plants. In the absence of these processes, nutrient discharges pose a risk of eutrophication – threatening in particular coastal waters and fish stocks.

Many problematic substances, such as residues of medicines or endocrine disrupters, also enter wastewater via urine and may subsequently be released into the environment. The Swiss Federal Institute of Aquatic Science and Technology (Eawag) has now shown that separate collection and treatment of urine could make significant contributions to water pollution control and nutrient recycling worldwide. The “NoMix” technology thus represents a major opportunity for urban water management.

Novaquatis tested various methods of processing urine. Ideally, treatment should permit recycling of nutrients as fertilizers and, at the same time, removal of problematic micropollutants. For example, 98% of the phosphorus in urine can be recovered by precipitation with magnesium.

The product – struvite – is an attractive fertilizer, free of pharmaceuticals and hormones. In Switzerland, nutrients from human urine could serve as substitutes for at least 37% of the nitrogen and 20% of the phosphorus demand that is currently met by imported artificial fertilizers.