[LUM#10] The Miraculous Benefits of Urine
When scientists and eco-entrepreneurs team up to reimagine the miracle of turning water into wine, the result is a very special vintage called “I’ll Pee on Your Vines.” Or, how the nutrients in our urine can be repurposed as fertilizer for grapevines. The Gospel of the Valurine Project according to Marc Héran, a researcher atthe European Membrane Institute (IEM).
The French consume drinking water—a lot of it—20% of which is used solely for flushing toilets. This water must then be transported to our wastewater treatment plants, treated, and returned to our natural environments. It’s a vicious cycle with staggering financial, energy, and environmental costs.
“We’re just now beginning to apply to water the same approach we took with waste twenty years ago, when we established recycling systems,” says Marc Héran, a researcher at theIEM. “When it comes to wastewater, however, the question is similar: can’t we recover the nutrients it contains for irrigation, for example?”
This water treatment specialist has been conducting this experiment since last year in collaboration with the Montpellier-based company Ecosec and the La Jasse winery in Combaillaux. For two years, two vineyard plots will be irrigated with fertilizers made from urine collected in dry toilets installed in the Hérault village and specially designed by Ecosec to separate urine and feces. The project is called Valurine.
From urine to fertilizer
“There is no doubt that the ecological transition is underway and will come to fruition. This growing awareness of our consumption patterns and their dependence on fossil fuels and raw materials is a major issue of the day,” the researcher emphasizes.
“Our urine contains most of the nutrients used as plant fertilizers: nitrogen, phosphorus, potassium…” explains Marc Héran. Phosphorus, essential for plants, is “a fertilizer that enables high agricultural yields. We extract it from phosphate mines, and we’re mining more and more of it.” It is a limited resource whose depletion could lead to a global agricultural crisis in the coming decades.
“Nitrogen, on the other hand, is an unlimited resource,” explains the researcher, “because it is present in the atmosphere. However, its cycle is extremely energy-intensive. " Wastewater treatment plants are required to treat nitrogen before discharging it into the natural environment to limit eutrophication (see box below). Once converted into gas, the nitrogen returns to the atmosphere before being captured again and converted back into liquid nitrogen to be used as fertilizer."
Strict controls
The question remains: how can this urine be used effectively? Urine can indeed contain micropollutants and pathogens, so sanitation and monitoring are carried out throughout the processing process. “We have not observed any accumulation of pathogens in the plants, and as for micropollutants, we are below detection limits,” says Marc Héran.
Another goal of the project is to optimize the management of urine volume, which is costly to store and transport. To reduce these costs, the Valurine project is testing several processes. These include the production of struvite, a powdered urine extract, and the concentration of urine through nitrification/distillation. “Struvite is extracted through a simple precipitation process, which recovers over 90% of the phosphate and some nitrogen in powder form by adding magnesium to the urine, which produces a precipitate.”
Concentrating urine requires a bit more expertise, as it must first be nitrified, as Marc Héran explains: “This involves stabilizing the nitrogen present in the urine in the form of ammonium by converting it into nitrate. ” The urine is then distilled “to preserve all the nutrients in just 5–10% of the original volume.”
The End of Universal Sewerage
Once concentrated in solution or in powder form, or simply used as is, the urine is ready for drip irrigation in the open fields. A small miracle that made possible the production of the very first bottles of wine resulting from this fertilization process. A fittingly named vintage: “I’ll Piss on Your Vines,” or the story of an eternal cycle where nothing is lost, nothing is created, and everything is put to good use. “Urine can change the face of agriculture, but also that of our planet; the 21st century will mark the end of the sewer system,” concludes the researcher.
Eutrophication: the suffocation of ecosystems
“Due to urban growth, wastewater treatment plants today discharge enormous volumes of water that ‘still contain far too many nutrients for rivers to naturally purify themselves, as was still the case 50 years ago,’ explains Marc Héran. “Algae grow rampantly, blocking out the light; they die and decompose, causing ecosystems to suffocate.” This phenomenon, known as eutrophication, has led authorities to impose standards on wastewater treatment plants regarding the discharge of nitrogen and phosphorus.
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