Modern green products recycled from human waste are excellent – and more importantly, safe fertilizers for agriculture, to address the climate crisis, biodiversity loss and pollution, and to meet humanity's need to transition to a circular economy, where all resources are recycled, according to a new study. The paper published on 16 January in the journal Frontiers in Environmental Science confirms the ecological and economic feasibility of recycling our body waste as fertilizer, provided there is no risk that harmful microbes or traces of drugs end up in the crops that are consumed.
Most of the nutrients required for plant growth are formed in human urine and feces. Urine is particularly rich in nitrogen and potassium, and also contains trace amounts of minerals such as boron, zinc and iron. Feces could also theoretically supply other nutrients such as phosphorus, calcium, magnesium or valuable soil organic carbon to the soil.
Lead author Ariane Krause, a scientist at the Leibniz Institute of Vegetable and Ornamental Crops in Großbeeren in Germany, said: Human urine contains multiple nutrients that are essential for plants to grow, like Nitrogen, Phosphorus or Potassium. We can collect urine, treat it in order to safely recycle the nutrients, remove pollutants like pharmaceuticals and pathogens and use it as a fertilizer.
"We found that recycling fertilizers produced from human urine are suitable for cabbage production, as one example of horticulture, because the fertilizers supply sufficient nutrients and we can yield comparable harvest," Krause told Daily News Egypt.
She further explained that the key in using human waste to feed plants is "source separation". We can collect human waste "at the source" in separating toilets. These are available with or without flush systems. Then we effectively treat the yellow and brown resources to remove pollutants, inactivate pathogens and transform the matter into safe recycling fertilizers.
On a practical level, there are various opportunities to collect human waste as a resource, such as in temporary toilets on festivals, in garden toilets, public toilets; but also in houses. There are various examples of pilot projects that already implemented resource-oriented sanitation systems with source separation, decentral treatment of human waste, according to the authors.
The recycling fertilizers could be used in agriculture, but also horticulture, for fertilizing parks and grass on public greens, or for replanting trees and energy crops.
