Swiss startup transforms urine into plant fertilizer

The Hidden Value in Human Urine

Most people don’t think twice about what happens to their urine once it’s flushed down the toilet. However, there's a growing movement to change that perspective. Human urine contains nitrogen, a vital nutrient for plants, and this has led to innovative solutions like those developed by VunaNexus, a Swiss start-up founded by siblings Nadège and David de Chambrier.

The traditional approach to agriculture relies heavily on nitrogen-based fertilizers, which are often produced using fossil fuels. This process is not only energy-intensive but also contributes to environmental degradation. According to Nadège de Chambrier, co-founder of VunaNexus, "we consider urine as waste, so what we’re trying to do is recycle it, closing the nutrients loop."

A New Approach to Wastewater Processing

VunaNexus has created a wastewater processing system that transforms urine into plant fertilizer by recycling its nutrients. The process involves dry urinals or urine-diverting toilets that channel urine into a biological reactor. Inside this reactor, two types of bacteria work together to stabilize the urine through nitrification, converting ammonium into nitrate. This step not only eliminates the smell of urine but also makes it suitable for further processing.

Once the urine has been nitrified, the resulting substance is filtered to remove micropollutants. It is then pasteurized and concentrated by a distiller, producing reusable distilled water and Europe’s first certified urine-based fertilizer called Aurin. The entire system is automated, remotely operated, and requires minimal maintenance, making it an efficient solution for large-scale applications.

Expanding the Application of Urine-Based Fertilizer

VunaNexus installs small wastewater treatment plants in the basements of large buildings or urban infrastructure. These systems extract wastewater from toilets, allowing the fertilizers to be sold in bulk to farmers or used by individuals for houseplants and gardens. Currently, the company has its treatment plants installed in six projects, including commercial, residential, and even one of the largest private banks in Switzerland.

While the team at VunaNexus is small, the company has attracted significant attention. They collaborate with the European Space Agency (ESA), whose MELiSSA project inspired the idea of reusing nutrients from human wastewater. This initiative explored regenerative systems for supporting astronauts during long-term space missions, and VunaNexus has adapted these concepts for use on Earth.

Environmental Impact and Future Vision

On Earth, nitrogen pollution from human urine is a significant, often overlooked, environmental issue. It affects water, air, and natural habitats. According to a study published in Scientific Reports, most human urine—rich in nitrogen and phosphorus—is released untreated into the environment, causing pollution and nutrient loss. VunaNexus treats approximately 8,000 liters (roughly 2,113 U.S. liquid gallons) of urine per day, preventing it from polluting rivers and lakes.

According to a social media post by the ESA, VunaNexus’ technology helps reduce carbon dioxide emissions, water waste, and nitrogen ground pollution. It also closes the nutrient loop, creating a system where resources are reused rather than discarded.

David de Chambrier, co-founder of VunaNexus, envisions a future where most large constructions in dense city centers will have technologies to recycle nutrients from urine. This shift could revolutionize how we manage waste and contribute to a more sustainable agricultural system.