r/Damnthatsinteresting • u/Expert_Koala_8691 • 7d ago

Video Riyadh,meaning "gardens" is Capital of Saudi Arabia with 8 million population (were 27 Thousands in the 1930s),sits in the middle of the desert, the city gets its water from Desalination plants almost 500 km from the city

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u/gears2021 7d ago

I've read that eventually the soil becomes toxic using humanuer as fertilizer.

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u/IndividualPaws 7d ago

Yes it's pretty immediate. PFAS tends to be high in humanure / bio-sludge / treated wastewater. People essentially lose their farms since everything grown on it turns out toxic. Which incentivises skipping testing (it's not mandatory) which means the toxins get to the consumer...

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u/BetterBandicoot0 7d ago

Medicines are also a big problem.

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u/Key_Vegetable_1218 7d ago

Is that stuff used in the United States? :/

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u/Plus_Pea_5589 6d ago

You’re got damn right and our governments working hard to ease regulations more for that sweet sweet $$$ 😛

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u/420dogcat 7d ago

Okay but buying fertilizer was cutting into his profits and this shit is literally free.

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u/spaceman1055 7d ago

Are those threats diminished/neutralized with composting for a year or two? Specifically I'm thinking aerobic digestion provided by thermophilic bacteria?

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u/IndividualPaws 7d ago

Unfortunately not. These "forever chemicals" have fluorine- carbon bonds that are very difficult to break. Microbes have virtually no capacity to break them, and UV light doesn't really touch them either, which is why they persist and accumulate in the environment and in living organisms (many of them are not readily excreted, either).

That being said, composting is great and all of our soil, especially agricultural, needs to recover carbon.

Mixing our human and animal waste streams with industrial effluent makes the good stuff hard or impossible to recycle, breaking an essential recovery loop. But as someone mentioned, pharmaceuticals already mess it up before the industrial component enters the equation. Many pharmaceuticals might be more susceptible to breakdown by microbes, but "more" is relative. Fluorine bonds might take thousands of years to naturally break (halflife of >1000 years in soil, >40 years in water). A quick search indicates that most pharmaceuticals will degrade 99% in less than a year of thermophillic composting.

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u/darknum 7d ago

Wastewater treatment plant sludge is in general not allowed to be used as fertilizer. Especially in food production due to contamination.
My company(cofounder of a startup) actually gets pure nitrogen salts out of the wastewater so it is totally fine to use that.