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  • B Madjaros

Can Human Waste be Repurposed?

Updated: Jul 7, 2023

Human waste. Often seen as useless material that our body can’t squeeze more nutrients from. But what about other things? Today we will be looking at a few uses for the waste, faeces specifically, writes B Madjaros


This is one of the options. This is a slightly debatable use. It can be used for plant fertiliser but it does have a few downsides. For example, if a human is ill or sick, this will be transmitted into the faeces and therefore into the plants. If another human ingests this plant, they might get the same disease if eaten soon enough after. Although no research has been done on the matter, it appears that human sickness cannot live in plants. Viruses from the digestive system, which should be the only ones getting into the compost, live for 2 months. It’s important to give three clear months before plants are harvested.

But what if the viruses mutate like Covid-19? Well, according to scientists, the coronavirus was in an obscure cave living in bats for millions of years to be able to jump to humans. First, the viruses would have to come into contact with the host ( plant), and then they would have to evolve, all the protein “keys” would have to mutate soon enough so that the virus doesn’t die. This is unlikely. But how would toilets have to be changed to accommodate this change and how would it happen?

Toilet issues

One option if this becomes the world normal, the toilets would have to be a pit so someone can collect the faeces easier. Another drawback for compost collection is the smell. But there are ways to neutralise the smell. According to cleaning expert Lily Cameron, if you place baking soda (a common baking ingredient) or white vinegar (a cooking ingredient) in the room, it will absorb the smell. And if you want to do it at home the composter won’t smell at all! You just need to add sawdust to absorb the smell and if you add other normal composter ingredients it will smell like normal as the poo contains nitrogen and the wood will absorb it.

But now that we have looked at faeces, what about urine? Well, it turns out it can also be used for fertiliser. Worldwide, 80% of urine flushed down the toilet isn’t treated and harms nature. But how can we use it if it is harmful to nature? Well, much like faeces, it becomes harmful when in contact with water and is rich with phosphorus, nitrogen and potassium which is amazing for plants but harms ocean life which is where it is dumped after it is “treated”. Urine traps can be made for toilets which store the urine aside before it gets wet in a container that you could pour on your plants!

"You can extract the sulphur from urine to make matches and gunpowder!"

Building Bricks

Urine and poo can also be used to build! Surprisingly enough if you use a urine trap again to get some urine in the toilet and add ureolytic bacteria and some sand that isn’t that stuck together. The bacteria isn’t good for humans but it won't make you ill. It will make a chemical called urease. This chemical will break down the urine and make calcium carbonate which is used in cement. The longer you leave it, the stronger it will get. But what about faeces? Well, when adding 25% of sewage waste into the brick it reached a 35.5 resistance of MPa with the minimum deemed acceptable for housing being 5MPa.

Brain Experiments & other

Yes. This is useful. There are a few cells shed from the kidney in urine. Scientists have found a way to turn them into stem cells. Stem cells with a little bit of effort can be turned into any cell from the animal which the stem cell came from. Scientists have made neurons (brain cells) from these stem cells and implanted them into (animal experimentation warning) baby mice. They have found that they do not form any tumours which would be almost certainly fatal if there were tumours. They even worked functionally fine and took half the time to grow!


I think today we have learnt a lot about human waste not being waste after all. In fact we are being wasteful by throwing it away. What is your favourite use for it, and why? For me the stem cells are the best.


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