Kretsloppsteknik

In a recent article published in BMC Environmental Science, Prithvi Simha and Gert van der Merwe argue that the term “green” ammonia is misleading, inaccurate, and overly simplistic.

Both brown ammonia and “green” ammonia are produced using the Haber-Bosch process. While brown ammonia is made using hydrogen extracted from fossil fuels, green ammonia uses hydrogen derived from renewable energy-powered electrolysis of water, thereby “greening” and decarbonizing ammonia synthesis. However, the nitrogen needed for Haber-Bosch ammonia synthesis is extracted from the atmosphere, an energy-intensive process that remains fundamentally linear for both types of ammonia. This anthropogenic nitrogen extraction has nearly doubled global nitrogen fixation, and already pushed the biogeochemical cycle of nitrogen beyond its safe planetary boundary.

Decarbonizing the global economy is essential, but focusing solely on reducing carbon emissions is shortsighted. To truly merit a green label, we argue that the fertilizer industry must adopt a planetary boundaries framework that extends beyond the current industry focus on merely offsetting or reducing carbon emissions from fertiliser production. The industry has a significant impact on nitrogen and phosphorus nutrient cycles and thus, has extended producer responsibility for minimising the environmental impacts of its products.

We think that the fertiliser industry should strive for creating products that substantially reduce reactive nitrogen and phosphorus fluxes to ecosystems. One solution here is to engage in the large-scale production of bio-based fertilizers. For instance, recycling humanurine alone could substitute about 25% of the nitrogen and phosphate fertilisers used in agriculture globally. Such recycling could offset the demand for anthropogenic nitrogen fixation via green/brown ammonia synthesis, while aligning food systems more closely with the principles of a truly green and circular economy.

Let’s redefine what it means to be “green” by considering the full environmental impact and embracing genuinely sustainable alternatives.

Read the full article here: https://lnkd.in/dKmxCz_S

Helloy! My name is Yulia, I’m coming from Finland, but study in Umeå University. About a year ago I finished bachelor programme in Life Sciences with specialisation in molecular biology, and now I’m studying master’s programme in chemistry. And though I’m planning to specialise in medicinal chemistry, my interests lay wide. Among them is wastewater treatment, for it’s both very important and also very interesting subject. This led me to Prithvi Simha’s research group. I’m here at SLU for a six-week internship, studying the potential of persulfate activation in urine with Ali Peter Mehaidli. Activation of persulfate will result into formation of sulphate radicals, and those in their turn will be degrading organic compounds in urine. Thus, the potential outcome of this study is to find a method of improving degradation of organic compounds in urine, while preserving nitrogen and phosphorus.

Hi! My name is Nathanaël, but everyone calls me Nate, so feel free to do the same. I am currently interning with the Environmental Engineering Research Group at SLU for three months, and I’ll be here until July 26th. I come from Strasbourg, France, where I attend ENGEES (National School of Water and Environmental Engineering, Strasbourg). Our focus is on all aspects of water, from the smallest water cycles to the bigger picture. Next school year will be my final year before I become an engineer. My specialty is water treatment, and I aspire to work in wastewater treatment plants or in a design office that deals with their dimensioning or startup. This interest led me to contact researcher Prithvi Simha, as I found the subject of urine separation particularly fascinating and underexplored at my school. I’m currently working and learning with PhD student Christoffer Parrow Melhus on urine collection pipes. In these pipes, urea breaks down into ammonia and carbon dioxide, leading to precipitation that can cause complete blockages. On a personal note, I enjoy discovering new things and was actively involved in student life at my school, organizing events for my peers. In my spare time, I like to go fishing to recharge my batteries.

Hello everyone! My name is Ariane and I’m from France, where I have been studying water and environmental engineering for 2 years at ENGEES in Strasbourg. I did 2 years of preparatory classes in physics and chemistry to get into this school and since then I have discovered all the issues involved in managing water to protect the environment. I also chose to specialise in water treatment. I am at SLU for a three-month internship in the urine group, where I am taking part in a study looking at how to degrade pharmaceuticals in urine to create a safe fertiliser, which will give me my first experience of research.

 

Prithvi Simha from our research group has been collaborating actively with partners in Namibia over the past three years. He has now joined the Gobabeb Namib Research Institute as a research associate/adjunct researcher. Gobabeb is a renowned center for dryland training and research located in the Namib Desert, approximately 120 kilometers southeast of Walvis Bay in Namibia. Prithvi in collaboration with Gert van der Merwe from Namibia University of Science and Technology, Eugene Marais from Gobabeb,a dn Christopher Malefors from SLU are running a joint project called “AirCloset” aimed at prototyping and evaluating a solar-thermal and wind-driven urine evaporator. Their goal is to develop a prototype evaporator that can effectively manage and utilize urine, transforming it into a valuable resource. Over the next nine months, they will pilot test the prototype evaporator at the Gobabeb Namib Research Institute. Gobabeb’s extensive weather station network and comprehensive environmental and meteorological data will play a crucial role in this phase. By leveraging these resources, they aim to gather detailed insights and refine the prototype for broader application. Stay tuned for updates on our progress and findings.

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.