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Media & Public Relations » Media Releases » Archive » 2007 » Urine source separation: a promising wastewater management option
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Urine source separation: a promising wastewater management option

Urine source separation: a promising wastewater management option

07 March 2007

Although urine makes up only 1% of the total volume of wastewater, it accounts for 50–80% of the nutrient content. Eawag has now shown that separate collection and treatment of urine could make significant contributions to water pollution control and nutrient recycling worldwide.

At this year’s Eawag Info Day – to be held at the Federal Institute of Technology (ETH), Zurich, on Wednesday, 7 March – the results of the Cross-Cutting Project " Novaquatis" will be presented to more than 250 scientists, wastewater professionals, administration officials and policymakers.

Although urine makes up only 1% of the total volume of wastewater, it accounts for 50–80% of the nutrient content. 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.