Globally, human excreta are a huge untapped source of nutrients. Now, a new perspective paper makes the case that biochar could help to unlock it.
The PNAS paper shows that human waste contains over 20 billion kilograms of nitrogen, almost 3 billion kilograms of phosphorus, and 6 billion kilograms of potassium annually. Urine alone contains the equivalent to 17% of global annual nitrogen needs, and up to 25% of potassium demand as well.
Extracting these valuable agricultural nutrients from waste products could help to build a powerful circular nutrient bioeconomy, the researchers believe: food becomes waste, which helps to grow food again, instead of being discarded and lost.
One can’t help but wonder if the process could also use condensers to turn the water vapor back into grey water perfect for irrigation.
Or, you know, golf courses in the desert.
I saw some tech a while ago referred that used hydrothermal carbonization which from what I can tell is a kind of “wet” pyrolysis. There was a company with a working demo system for sewage treatment which seemed promising, but I haven’t heard any new developments since I heard about them a few years ago. I don’t know if it’s just all up in regulatory processes or if it fizzled out.
We already get fertilizer from sewage don’t we? It’s a huge source of micro plastics in agriculture 😭
The pyrolysis process that the article refers to can turn organic material into biochar which is essentially charcoal. Organic material being anything that has carbon in it which does include sewage and critically plastics. There are studies about using biochar as reusable microplastic adsorption material but I’m not really qualified to draw any conclusions
