Prithvi Simha

Recycling resources from wastewater fractions like human urine contributes to a sustainable future and a circular economy in sanitation. This approach reduces human impacts on planetary boundaries, particularly nitrogen and phosphorus cycles, while supporting and complementing centralised wastewater treatment systems. 

My current work focuses on developing technologies to treat source-separated urine for the production of concentrated fertilisers, such as granurin, nitrogen-rich fertiliser pellets containing over 15% nitrogen), as well as clean water and high-value chemicals. I also design methods to remove heavy metals, pathogens, and micropollutants, including pharmaceutical residues, from urine and urine-derived products.

I am a contributing author to the United Nations Environment Program and Global Wastewater Initiative flagship report, ‘Wastewater – Turning Problem to Solution’, and serve on the management committee for the International Water Association’s Specialist Group on Resource-Oriented Sanitation.

My research combines natural sciences with chemical and environmental engineering. I particularly enjoy prototyping, field-testing, and implementing new technologies in real-world settings. Alongside this, I use systems analysis tools to better understand how new sanitation technologies and behaviours can be adopted at scale in society. 

Mentoring students is one of the most rewarding parts of my job. I supervise projects across a wide range of topics, from lab- and field-based experiments to socio-technical studies that map nutrient flows, identify cultural barriers to recycling, or analyse large datasets on food and sanitation systems. If you're interested in contributing to this field, feel free to get in touch. I welcome thesis and internship students throughout the year. Ongoing projects are based in Sweden, Namibia, Ethiopia, Bolivia, and India.

Ph.D. Technology, Swedish University of Agricultural Sciences

M.Sc. Environmental Sciences, Policy, & Management, Joint Degree from the University of Manchester, Lund University and Central European University.

B. Tech. Chemical Process Engineering at VIT University, India.

Gao, Y., Vinnerås, B., & Simha, P.* (2025). Partitioning behavior and crystallization of urea, salts and water during stepwise dehydration of acidified human urine by evaporation. The Science of the total environment, 966, 178709.

Courtney, C., Al-Saadi, A., & Simha, P.* (2025). Balancing the oxidation of endogenous organics and macronutrient recovery from human urine treated with fenton’s reagent: A targeted metabolomics study. Chemical Engineering Journal Advances, 100772.

Simha, P.* & van der Merwe, G. (2024). Is “green” ammonia a misnomer? Unpacking the green label from a food-water-energy nexus perspective in water-scarce regions. BMC Environmental Science, 1(1), 5.

Simha, P.*, Courtney, C., & Randall, D. G. (2024). An urgent call for using real human urine in decentralized sanitation research and advancing protocols for preparing synthetic urine. Frontiers in Environmental Science, 12, 1367982.

Mehaidli, A. P., Mandal, R., & Simha, P.* (2024). Selective degradation of endogenous organic metabolites in acidified fresh human urine using sulphate radical-based advanced oxidation. Water Research, 257, 121751.

Perez-Mercado, L. F., Simha, P.*, Moreira, A. P., Paulo, P. L., & Vinnerås, B. (2024). Circular fertilisers combining dehydrated human urine and organic wastes can fulfil the macronutrient demand of 15 major crops. Science of the Total Environment, 951, 175655.

van der Merwe, G., & Simha, P.* (2023). Approaches for bridging the sanitation delivery gap in urban informal settlements in Namibia. City and Environment Interactions, 20, 100120.

Demissie, N., Simha, P., Lai, F.Y., Ahrens, L., Mussabek, D., Desta, A. and Vinnerås, B.  (2023). Degradation of 75 organic micropollutants in fresh human urine and water by UV advanced oxidation process. Water Research, 120221.

Perez-Mercado, L. F., Perez-Mercado, C. A., Vinnerås, B., & Simha, P.* (2022). Nutrient stocks, flows and balances for the Bolivian agri-food system: Can recycling human excreta close the nutrient circularity gap? Frontiers in Environmental Science, 10, 956325

Zhou, X., Simha, P.*, Perez-Mercado, L. F., Barton, M. A., Lyu, Y., Guo, S., ... & Li, Z. (2022). China should focus beyond access to toilets to tap into the full potential of its Rural Toilet Revolution. Resources, Conservation and Recycling, 178, 106100.

Simha, P.*, Barton, M.A., Perez-Mercado, L.F., et al. (2021). Willingness among food consumers to recycle human urine as crop fertiliser: Evidence from a multinational survey. Science of The Total Environment, 765, 144438.

Simha, P.*, Senecal, J., Nordin, A., Lalander, C., Vinnerås, B., 2018. Alkaline dehydration of anion–exchanged human urine: Volume reduction, nutrient recovery and process optimisation. Water Research 142, 325-336.

Simha, P., Lalander, C., Vinnerås, B., Ganesapillai, M., 2017. Farmer attitudes and perceptions to the re–use of fertiliser products from resource–oriented sanitation systems–The case of Vellore, South India. Science of The Total Environment, 581-582, 885–896.

Senecal, J., Nordin, A., Simha, P., Vinnerås, B., 2018. Hygiene aspect of treating human urine by alkaline dehydration. Water Research, 144, 474-481.

Simha, P., Alkaline Urine Dehydration: How to dry source-separated human urine and recover nutrients? Doctoral Thesis, Sveriges lantbruksuniversitet, Acta Universitatis Agriculturae Sueciae, 1652-6880. 

United Nations Environment Programme (2023). Wastewater – Turning Problem to Solution. A UNEP Rapid Response Assessment. Nairobi, Kenya. [features three case studies on urine source-separation and recycling from SLU/S360]

Simha, P., Vinnerås, B. (2022). The disruptive opportunity for mainstreaming urine recycling. IWA Source Magazine. 

Simha, P., Buckley, C., Senecal, J. (2020) We developed a simple process to recycle urine. Here’s how it’s done. The Conversation Africa. 

Simha, P., Vinnerås, B., Senecal J. (2020) We found a way to turn urine into solid fertiliser – it could make farming more sustainable. The Conversation UK.