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 also complementing centralised wastewater treatment systems.
Currently, my work focuses on developing technologies to treat human urine for the production of concentrated fertilisers, such as granurin (nitrogen-rich fertiliser pellets containing over 15% nitrogen), high-value chemicals, and clean water. I am also developing methods to remove heavy metals, pathogens, and micropollutants, including pharmaceutical residues, from urine and urine-based 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 Specialist Group on Resource-Oriented Sanitation of the International Water Association.
My research combines natural sciences with chemical and environmental engineering. I enjoy prototyping, field-testing, and implementing new technologies in real-world settings. I also apply systems analysis tools to strategize the adoption of new sanitation technologies and behaviours in society.
I like mentoring students, so if you're interested in contributing to circularity in the water and sanitation space, feel free to reach out!
Research Projects
Ph.D. Technology, Swedish University of Agricultural Sciences
Erasmus Mundus M.Sc. Environmental Sciences, Policy, & Management (MESPOM): University of Manchester, Lund University, Central European University, University of Aegean.
B. Tech. Chemical Process Engineering at VIT University, India. Indus–Magic scholar at National Chemical Laboratory, CSIR India. Summer Research Fellow at Institute of Chemical Technology, India.
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.
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.
Aliahmad, A., de Morais Lima, P., Kjerstadius, H., Simha, P., Vinnerås, B., & McConville, J. (2025). Consequential life cycle assessment of urban source-separating sanitation systems complementing centralized wastewater treatment in Lund, Sweden. Water Research, 268, 122741.
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.
Arve, P. H., Mason, M., Randall, D. G., Simha, P., & Popat, S. C. (2024). Concomitant urea stabilization and phosphorus recovery from source-separated fresh urine in magnesium anode-based peroxide-producing electrochemical cells. Water Research, 256, 121638.
Demissie, N., Simha, P.*, Vasiljev, A., & Vinnerås, B. (2024). Photoinactivation of jack bean (Canavalia ensiformis) urease in fresh human urine using dichromatic low-pressure UV irradiation. Chemical Engineering Journal, 484, 149708.
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.
Li, T., Li, Y., Li, Y., Li, Z., Zhou, X., & Simha, P.*(2024). Leveraging a sanitation value chain framework could address implementation challenges and reinvent China’s Toilet Revolution in rural areas. Frontiers in Environmental Science, 12, 1390101.
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.
Deka, A., Simha, P.*, Nazarova, L., Kataki, R., & Vinnerås, B. (2023). Degradation of poly-L-lactic acid biopolymer films in Ca (OH) 2-dosed fresh human urine collected in source-separating sanitation systems. Resources, Conservation and Recycling, 198, 107202.
Simha, P.*, Vasiljev, A., Randall, D. G., & Vinnerås, B. (2023). Factors influencing the recovery of organic nitrogen from fresh human urine dosed with organic/inorganic acids and concentrated by evaporation in ambient conditions. Science of The Total Environment, 163053.
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.
Simbeye, C., Courtney, C., Simha, P.*, Fischer, N., & Randall, D. G. (2023). Human urine: A novel source of phosphorus for vivianite production. Science of The Total Environment, 164517.
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.
Aliahmad, A., Harder, R., Simha, P., Vinnerås, B., & McConville, J. (2022). Knowledge evolution within human urine recycling technological innovation system (TIS): Focus on technologies for recovering plant-essential nutrients. Journal of Cleaner Production, 134786.
Simha, P.*, Deb, C. K., Randall, D. G., & Vinnerås, B. (2022). Thermodynamics and Kinetics of pH-dependent Dissolution of Sparingly Soluble Alkaline Earth Hydroxides in Source-Separated Human Urine Collected in Decentralised Sanitation Systems. Frontiers in Environmental Science, 10, 889119.
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.
Vasiljev, A., Simha, P.*, Demisse, N., Karlsson, C., Randall, D. G., & Vinnerås, B. (2021). Drying fresh human urine in magnesium-doped alkaline substrates: Capture of free ammonia, inhibition of enzymatic urea hydrolysis & minimisation of chemical urea hydrolysis. Chemical Engineering Journal, 428, 131026.
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.*, Lalander, C., Nordin, A., & Vinnerås, B., 2020. Alkaline dehydration of source-separated fresh human urine: Preliminary insights into using different dehydration temperature and media. Science of The Total Environment, 733, 139313.
Simha, P.*, Karlsson, C., Viskari, E-L., Malila, R., and Vinnerås, B. (2020) Field testing a pilot-scale system for alkaline dehydration of source-separated human urine: a case study in Finland. Frontiers in Environmental Science, 8, 570637.
Simha, P.*, Senecal, J., Gustavsson, D. J., & Vinnerås, B. (2020). Resource recovery from wastewater: a new approach with alkaline dehydration of urine at source. In Current Developments in Biotechnology and Bioengineering (pp. 205-221). Elsevier.
Simha, P.*, Lalander, C., Ramanathan, A., Vijayalakshmi, C., McConville, J. R., Vinnerås, B., Ganesapillai, M., 2018. What do consumers think about recycling human urine as fertiliser? Perceptions and attitudes of a university community in South India. Water Research 143, 527-538.
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.
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., 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.
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.
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.
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