Human urine contains Nitrogen (N), Phosphorus (P), and Potassium (K), which are key nutrients for human health and plant growth. However, phosphorus is a limited resource and fertilizers containing NPK are produced by energy-intensive and environmentally-harmful processes.

NPK from fertilizers are used to grow food that we eat and they exit our bodies in wastewater. Removing NPK from wastewater would allow us to reuse these limited resources, but nutrient removal at wastewater treatment plants is costly and energy intensive, and incomplete removal leads to nutrient pollution in environmental waters. Separating urine from wastewater can mitigate nutrient pollution while reducing costs and energy usage. Separated urine can be processed into a fertilizer, reducing greenhouse gas emissions and energy consumption associated with commercial fertilizer production. To implement urine separation at municipal scales, research is needed to weigh the risks and benefits of the technology to users, the environment, and the socioeconomic factors in a water system.

Source-separated urine can contain human pathogens, including viruses and bacteria. Our research has focused on the detection and mechanistic fate of pathogens found in source-separated urine. For example, we have studied the persistence of polyomaviruses as well as bacteriophage surrogate viruses in separated urine as it is stored. We characterized the removal/inactivation of viruses as the urine is converted to fertilizer through various unit processes. We have also quantified the release of viruses into the bathroom environment when toilets containing urine are flushed. Finally, we studied the bacterial communities in source separated urine and characterized how they shift as the urine is stored and converted to fertilizer.