We modern people don’t really think of human urine when it comes to fertilizing plants. especially, amidst the development of technology that enables us to improve agriculture.
Nonetheless, researchers today have been looking for ways to reduce reliance on chemicals and cut environmental pollution. And some of them have looked at the good old kidney secretion.
Engineer Fabien Esculier is one, for example. According Esculier, plants need nutrients: nitrogen, phosphorus and potassium. Meanwhile, we humans have them all through food, before letting them go through urine. That’s why there’s a potential in it.
Since a long time, fertilizers have used synthetic nitrogen. It’s helped boost agricultural production and the number of yields so that we humans can eat.
Unfortunately, when used in large quantities, the fertilizers make their way into river systems and other waterways. That causes algae blooms, which despite its good-sounding features since many things are now made from algae, they suffocate fish and other aquatic life.
Moreover, per the UN, emissions from this agricultural ammonia can combine with vehicle fumes to create dangerous air pollution. Other than that, the emissions also include nitrous oxide, a type of potent greenhouse gas that contribute to climate change.
One thing to note, though, is that nitrogen pollution doesn’t come directly from agriculture only.
Pollution from wastewater
Julia Cavicchi of the United States Rich Earth Institute said, “Modern-day sanitation practices represent one of the primary sources of nutrient pollution.” According to Cavicchi, urine is responsible for around 80% of nitrogen found in wastewater and more than half of the phosphorus.
To replace chemical fertilizers, one would need many times the weight in treated urine.
But Cavicchi said, “Since the production of synthetic nitrogen is a significant source of greenhouse gases, and phosphorus is a limited and non-renewable resource, urine diverting systems offer a long-term resilient model for human waste management and agricultural production.”
A study by UN researchers done in 2020 suggested that global wastewater has the theoretical potential to offset 13 percent of the world’s demand for nitrogen, phosphorus and potassium in agriculture.
There’s just one caveat: it’s not as easy as it sounds.
Collecting pee in the past vs present
Now, it is true that in the past, before the finding of the chemical alternatives, people transported around this excrement from urban areas to agricultural fields to be used as fertilizer.
It was easier then, because of chamber pot use, and people of olden days were more open to such ideas. Now, if we want to collect urine, we have to rethink the sewage system and also toilets.
There is a long-term project to do that, and it began in Sweden in the early 1990s in a number of eco-villages. Such projects have now spread in Switzerland, Germany, the US, South Africa, Ethiopia, India, Mexico and France.
Tove Larsen at Switzerland’s Eawag aquatic research institute said, “It takes a long time to introduce ecological innovations and especially an innovation such as urine separation which is very radical.”
Larsen stated that the early urine-diverting toilets were considered unsightly and impractical, or raised concerns about unpleasant odors. Nonetheless, the researcher hoped that a new model would solve the issues, with a design that funnels urine into a separate container.
Processing the urine and other challenges
After collecting the pee, what needed to be done next is processing it. There are many substances contained in human urine, and not all are needed in order to be made fertilizer.
Some of you may ask if human urine in present time is okay because of the modern diet and diseases. Well, the World Health Organization stated that urine is not normally a major carrier of disease, so it recommends leaving it for a period of time or pasteurize it if one wants to.
Other than that, there are also techniques for concentrating or even dehydrating the liquid, reducing its volume and the cost of transporting it to the fields.
However, one of the real challenges is making people accept urine collection and fertilization more. Are they ready to eat urine-fertilized food?
According to a study, the acceptance rate is very high in China, France and Uganda, but low in Portugal and Jordan.
Trying to make them realize that it’s not something to be feeling yucky about—even though the urine will go through a process first—is going to take some time.
Is it a better fertilizer after all?
Other than the mentioned benefits above, human urine-derived fertilizers also provide another plus point: low risks of transferring antibiotic resistant DNA to the environment.
New research from the University of Michigan may have found a key finding in efforts to identify more sustainable alternatives to the conventional, water-polluting fertilizers.
As we know, current municipal treatment systems don’t totally remove these nutrients from wastewater before it’s released into rivers and streams. At the same time, manufacturing synthetic fertilizer is expensive and takes a lot of energy.
Well, what if the one that can change it all is recycled and aged human urine?
Over the last few years, the research group has studied the removal of bacteria, viruses, and pharmaceuticals in urine to improve the safety of urine-derived fertilizers.
But in this new study, they show that the practice of aging urine in sealed containers over several months lead to a very positive result. It effectively deactivates 99% of antibiotic resistant genes that were present in bacteria in the urine.
Corresponding author Krista Wigginton said, “Based on our results, we think that microorganisms in the urine break down the extracellular DNA in the urine very quickly.
“That means that if bacteria in the collected urine are resistant to antibiotics and the bacteria die, as they do when they are stored in urine, the released DNA won’t pose a risk of transferring resistance to bacteria in the environment when the fertilizer is applied.”
Previously, research has shown that there’s antibiotic-resistant DNA in urine. Thar raised the question of whether fertilizers derived from it could carry over that resistance.
Testing the (urine) waters
For this study, the researchers collected urine from more than 100 men and women and stored it for 12 to 16 months.
During the aging period, ammonia levels in the urine increase, lowering acidity levels and killing most of the bacteria that the donors shed. FYI, bacteria from urinary tract infections often harbor antibiotic resistance.
When the ammonia kills the bacteria, they dump their DNA into the solution. Consequently, the DNA is what the researchers examined to see how quickly they would break down. And well, it’s quick enough that the researchers believe it’d be a good material for fertilizers that lead to a sustainable, circular nutrient economy.
Wigginton said, “There are two main reasons we think urine fertilizer is the way of the future. Our current agricultural system is not sustainable, and the way we address nutrients in our wastewater can be much more efficient.”
After this, the researchers are trying to find out how the fertilizers are doing in agricultural settings. Professor of civil and environmental engineering at U-M Nancy Love added, “We are doing field experiments to assess technologies that process urine into a safe and sustainable fertilizer for food crops and other plants, like flowers. So far, our experimental results are quite promising.”
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