Traditional agricultural societies in the past lacked modern chemical fertilizers and therefore leveraged stools for fertilization purposes. Hence, there once existed a profession in which workers transported stools from urban areas to the countryside. Although few farmer still utilize this method for fertilization, the recent trend of carbon reduction has prompted scientists to once again revisit the concept of natural fertilizers.
Contemporary fertilizers contain nitrogen, phosphorous, and potassium. Nitrogen fertilizers are manufactured from ammonia through the Haber process, which synthesizes ammonia from nitrogen and hydrogen. The resultant ammonia is then combined with carbon dioxide into urea. Manufacturing ammonia using the Haber process requires high temperature, pressure, and energy, not to mention massive amounts of carbon emissions. Chemical phosphorous fertilizers source their phosphorous from phosphates. Mining, transportation, chemical raw materials, and the manufacturing processes all involve the emission of carbon. Phosphorous fertilizer over-deployment, furthermore, generally result in eutrophication of waterbodies. Finally, despite the relatively high potassium content in the earth, potassium chloride is frequently mixed with sodium chloride, meaning various methods are required to separate the two, in turn leading to various levels of energy expenditure.
From the perspective of carbon reduction-driven environmentalism and developmental reduction, rather than mining, which destroys the environment, and consuming energy to manufacture, it would make more sense to “go natural” via reuse. Given that urine contains nitrogen, phosphorous, and potassium required for fertilizing plants, harnessing the wisdom of the ancients appears to be the right move. Modern technology is able to achieve what was previously thought of impossible. Urine contains various bacteria, hormones, disease vectors, and antibiotics (thanks to modern medical science), all of which need to be prevented from spreading. Modern technology can filter all of the above.
Led by the University of Technology Sydney, schools such as Griffith University have been engaging in the “Nutrients in a Circular Economy” study to investigate the economic feasibility of using human urine as fertilizers and the potential resultant health risks.
As part of the aforementioned plan, Griffith University will start testing urine-recycling toilets in Brisbane and Sydney based on filtration technology developed by the University of Melbourne. The test is expected to last four years and spans the study of various toilet designs to investigate superior ones. This filtration technology is able to self-generate electricity and, through electrical potential as well as filtration film, separate out the useful elements contained in the urine. It should also be pointed that the tubes used for this technology can be as small as 20 cm. The research team indicates that fertilizers manufactured with this technology smells like ammonia somewhat, albeit weaker than the smell of urine.
In addition to topics in carbon reduction, sourcing phosphorous is yet another topic of global focus, since Morocco and Algeria, the two main sources of phosphate, have maintained a hostile relationship, with armed conflicts an ever-looming possibility. Furthermore, while Syria is embroiled in a civil war, and China is a major consumer of fertilizers, the supply of phosphorous is entangled in geopolitical risks.
On the other hand, western environmentalists believe that the lifecycle of phosphorus fertilizers ends in the water, whether through over-fertilizing, which ends with said fertilizers flooding into various waters, or through human consumption of fertilizer-rich foods, which will eventually be flushed down the toilet. Not only does this cause eutrophication, but humanity also has no cost-effective way of retrieving back the phosphorous outputted into the ocean, meaning that one day, the earth’s supply of phosphorous will likely run out. Hence, recycling phosphorous from urine may potentially be a welcoming development in environmentally conscious countries in Europe.
The future may see history repeat itself as urban dwellers once again have their stools recycled into fertilizers for agricultural purposes. Humanity’s pursuit to reduce its carbon emissions and phosphorite consumption through recycling fertilizers perfectly embodies the ideal of keeping “it” in the proverbial family of mankind.
(Image shown for illustration purposes only; source: Pixabay)