Fate of pharmaceuticals and bacteria in stored urine during precipitation and drying of struvite

Experiments were conducted to measure the behaviour of eight pharmaceuticals during urine treatment as part of the project ‘SANIRESCH – Sustainable sanitary recycling Eschborn’. Urine was collected from 200 people in a public building via waterless urinals and NoMix toilets. It was then stored at room temperature at different pH values to analyse the extent to which bacteria and pharmaceuticals are eliminated over time. Although a partial elimination of pharmaceuticals could be detected, the storage at defined pH values cannot be advised. As the persons tested used pharmaceuticals with different structures, in different amounts and at varying intervals, this method of treatment is insufficient for removing them from urine. Precipitating the urine with MgO, washing it with saturated struvite solution and drying it at 30 °C will result in a free-flowing granular powder of struvite (NH₄MgPO₄·6H₂O) that is free of pharmaceuticals and pathogens and can be used as fertiliser and a source of nitrogen, magnesium and phosphorus.