Tag: Source-separating sanitation systems

The metabolome of real human urine is highly complex. Many of the organic compounds in urine significantly influence treatment parameters such as energy demand and product purity when urine is treated in resource-oriented sanitation systems. In a study  published in Water Research, Ali Mehaidli and Prithvi Simha from our research group developed a method using heat-activated peroxydisulphate for the selective degradation of organic compounds in human urine.

Key Findings

• Optimal Conditions: The best conditions for peroxydisulphate activation in real urine were a dose of 60 mM, a temperature of 90°C, and a reaction time of 1 hour at a pH of 3.0. Under these conditions, over 90% of the peroxydisulphate was activated.
• Selective Degradation: More than 150 organic metabolites were degraded in real urine, with a significant reduction in chemical oxygen demand and total organic carbon, indicating effective degradation of complex organic molecules.
• Minimal Urea Loss: The process resulted in less than 10% loss of total nitrogen, with most of the urea remaining intact. This is crucial for maintaining the nutrient value of urine for recycling purposes.
• Chloride Oxidation: The treatment did not oxidise chloride, suggesting minimal risk of forming harmful chlorinated byproducts

Researchers at Clemson University, the University of Cape Town, and the Swedish University of Agricultural Sciences have developed a new way to recover valuable nutrients from urine. This method, described in the journal Water Research, uses a special electrochemical cell that synthesise hydrogen peroxide in real human urine which stabilizes urea and alkalises urine to recover phosphorus as precipitates. The cell features a magnesium (Mg) anode and a carbon-based gas-diffusion cathode. The effectiveness of the process depends on the current density (the amount of electrical current per unit volume of urine). Lower current densities stabilize urea and facilitate the formation of struvite without significantly increasing the urine pH. Higher current densities produce more H2O2 but can cause the urine pH to rise too much, leading to the formation of less desirable calcium phosphate solids instead of struvite. Overall, the study provides a novel approach to stabilise human urine at source, without the need for physical dosing of chemicals, making nutrient recovery from urine more practical and safer. For more detailed information, the full study is accessible at:

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.

Exciting news! At the Swedish University of Agricultural Sciences (SLU), where all three of Sanitation360’s founders have studied and now work, a new bathroom installation has been in the works. And as of last week, after an incredibly impressive effort by Jenna, version 2.0 is finally ready to be used on the 5th floor at the Department of Energy and Technology at SLU in Uppsala, Sweden.

The bathroom contains one of Laufen’s urine-diverting toilets, which we’ve connected to our urine concentrator – and now we’ve also added our own addition to the flush system. Usually, both urine and 220 ml of flushwater end up being diverted into the urine collection tank, per flush. Whilst this is no issue in terms of purity, it is an issue in terms of energy usage later on in the urine to fertilizer process.

Urine consists of about 95% water, which contains no nutrients. Therefore, our urine concentrator is designed to effectively remove/evaporate the water, leaving us with the nutritious 4% of the urine. This is already a large amount of water to remove and with additional flushwater in the system, it rapidly increases the energy requirements. To make it more sustainable, we want to reduce, and favourably completely stop, any flushwater from entering the urine collection tank and instead divert it to the wastewater pipe. This is exactly what our new installation now does – thanks to Jenna and David Fredriksson at Davitor AB.

There is now a sensor that detects incoming flushwater and triggers the valve to the urine collection tank to close. The system also has a reactor with a level sensor to enable automatic pumping of urine into to the concentrator, where the urine is dried.

So if you ever happen to be in Uppsala, make sure to give it a visit and let us know what you think of it!

The white container on the right side is our concentrator which the urine is first diverted into and then dried into a nutrient rich mass. Attached to the wall behind it is our newly installed system which detects when someone is flushing and closes the valve to the urine collection tank. The program showcased on the computer shows how the different valves and sensors are working together to achieve this. Lastly, you can see Laufen’s beautiful urine-diverting ”Save!” toilet which we are big fans of!

The choices we make matter. The choices we make as scientists can significantly impact society. In this perspective article published in Frontiers in Environmental Sciences, Caitlin Courtney, Dyllon Randall and I focus on one such methodological choice in decentralized sanitation research: whether to use real human urine or synthetic/artificial urine for experimentation.

For various reasons, many studies opt for synthetic urine over real human urine, relying on recipes for making synthetic solutions that mimic real urine. Using synthetic solutions as stand-ins for real fluids is a legitimate scientific method, and one that is not uncommon in wastewater research. But exclusively using synthetic urine can present methodological challenges, especially when protocols for its preparation are not well-established and validated against real urine. This article highlights some of the compositional and property differences between synthetic urine and real urine, and the implications of these differences on experimental outcomes and their real-life implications.

We hope this article sparks a dialogue within the research community on the benefits of using real urine in experimental research. We strongly encourage researchers involved in this field to collaborate in establishing standardized terminology, definitions, methodologies, and best practices for sanitation-related research involving human urine.

If you are interested in furthering this effort, please do reach out to us!

Simha, P., Courtney, C., & Randall, D. G. 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.

My name is Oliver. Currently, I am in my final year of studies at Tampere University of Applied Science. My association with the urine drying team dates back to the summer of 2022. During that period, I was involved in researching various methods for the acidification of urine. The primary objective of this research was to prevent the process of enzymatic urea hydrolysis, thereby preserving nitrogen in urine. I have now returned to SLU to write my BSc thesis, where I will focus on exploring techniques for the removal of organic micropollutants. These pollutants, can have significant environmental impacts, especially in aquatic environments. Through my research, I aim to contribute to the development of more sustainable and effective waste management practices.

Hi, I am Isis Conroy. I am in the final year of my bachelor’s degree in environmental engineering at Tampere University. Last year, I was at SLU working alongside Natnael Demissie with lab duties relating to his doctoral thesis which evaluated the effect of UV and peroxide on antimicrobial-resistant bacteria and their genes. This year I have returned to do my own thesis working on a project that aims to standardize a methodology for assessing urea hydrolysis in urine by utilizing bacterial urease rather than jack bean urease. In both my work and hobbies, I enjoy microbiology, microscopy, and mycology. In my free time, I am a mushroom guide, teach microscopy lectures to children, and I enjoy spending time outdoors. I will be at SLU until I present my thesis in early June.

The SLU Urban Futures hub in Ultuna has granted funding to three interdisciplinary projects focusing on the Urban Food-Energy-Water nexus, one of which is called “The AirCloset” that will be led by Prithvi Simha from SLU, Sweden and Gert van der Merwe from NUST, Namibia.

The Air Closet and Granurin Technology:
The project will pioneer the development of a toilet that separates and dehydrates urine using solar-thermal energy. This not only provides a sustainable solution for sanitation in informal settlements but also presents a unique opportunity for recycling urine into a great fertilizer – Granurin.

Granurin, a Fertilizer Revolution:
Granurin, with its 20% nitrogen content, represents a revolutionary step in sustainable agriculture. Simha and his colleagues at SLU have successfully developed a technology to dehydrate urine, creating these safe fertilizer pellets that can potentially replace synthetic fertilizers. This not only contributes to circular food production but also opens up a global avenue for local food security enhancement.

Impact on Urban Informal Settlements:
Taking the technology a step further, the project aims to implement urine drying in urban informal settlements, where over a billion people reside without access to basic services. By providing a solution that integrates sanitation, agriculture, and economic empowerment, The Air Closet challenges the status quo, striving to uphold the promise of Agenda 2030 – “leave no one behind.”

FoodsecURe: Food security through better sanitation is a NRC funded 4 year research project (2023-2027) that targets the small-scale producers around the outskirts of Bahir Dar city who also participate in the on-going EU H2020 funded project “Healthy Food Africa” (HFA). FoodsecURe is coordinated by NIBIO with Dr Divina Gracia P. Rodriguez as Project Manager, with partners including the Kretsloppsteknik group at the Swedish University of Agricultural Sciences (SLU), the Norwegian University of Life Sciences (NMBU), Norges Vel, Bahir-Dar University (BDU), and Amhara Regional Agricultural Research Institute. BDU office of the Healthy Food Africa project, Bahir Dar City Water Supply and Sewerage Authority, and the Bureau of Water and Energy are key stakeholders and members of the Advisory Committee of the project from the Ethiopian side.

We have recently published a paper in Resources, Conservation and Recycling which looks into the possibility of using Poly-L-Lactic Acid (PLLA) biopolymer to capsulate and safely dose chemicals to human urine.

Alkaline dehydration of urine for recycling of plant essential nutrients requires fresh urine to be stabilized with alkali or metal hydroxides. Improper handling and exposure to these chemicals may cause skin or breathing irritation. Therefore, if these chemicals are wrapped inside capsules made of a biopolymer, human interaction with these chemicals can be minimized and chemicals could be passively dosed to urine. These capsules can also be used for dosing of oxidants and peroxides for the removal of micropollutants and pharmaceuticals from urine.

In the study, degradation of PLLA films in Ca(OH)₂ dosed fresh urine was evaluated with temperature, thickness and pH being the variables. The results of this investigation provided some really interesting results in terms of physiochemical changes in the urine and the physical, chemical and molecular changes of the films. If you are interested to find out more and read the full article, click here: https://www.sciencedirect.com/science/article/pii/S0921344923003361 .