Viewing a single comment thread. View all comments

youshouldbethelawyer t1_j5v86kb wrote

Humans poop 3g of phosphorus per day

105

GeekSumsMe t1_j5vfh7b wrote

This is the answer.

The ironic part of all of this is that many of our waters are degraded due to excess nutrients, particularly P.

A major source is human poop.

Waste water treatment plants have the tech to remove P, but are resistant due to initial infrastructure costs.

88

Sanpaku t1_j5vn48x wrote

If we don't start recycling that poop to fertilize crops, or learn how to cost-effectively extract P from seawater, we have at best a few centuries of global populations that number in the billions.

How's this for euphemism:

>Fig. 1 shows the predicted global population passing through 7 billion in 2010 and shortly after peaking at 7.3 billion. It can be seen that after the peak, the population will sink down to a level of 5.5–4 billion people for as long as the low grade (1800–2250) and ultra low grade (1800–3300) deposits can be mined. High- grade reserves run out in 2040, low grade reserves run out around 2340 and the ultra low grades around 3100 AD. After 3100, the only market available P will be that recycled. The peak behaviour is evident, production from high-grade reserves occurs 1960– 2050, from low grade ore 2080–2220, and ultra low grade ore 2300–3600. When all of these are exhausted, a food-based population reduction will follow.

30

GeekSumsMe t1_j5xk1pe wrote

My point was that we are needlessly polluting our water bodies when we could be capturing the pollutant and putting it to beneficial use.

The pollution caused by P (and N) is the most urgent need. The ability to benefit is a secondary and important benefit.

About half of the rivers and streams cannot support the amount of nutrients that we deliver and this is a problem that continues to get worse.

14

TheLostHippos t1_j5yn8vp wrote

We are already finding incredible uses for human waste that may be able to provide many sources of food and nutrients.

There's the classic nightsoil method of using untreated human fertilizer but we've started developing new technologies to turn human excrement into both biogas and treated fertilizer!

Then there are other plans like letting Black Soldier Fly Larva eat human excrement and then turning them into a protein rich food source for animals.

2

AftyOfTheUK t1_j5wx30y wrote

>If we don't start recycling that poop to fertilize crops, or learn how to cost-effectively extract P from seawater, we have at best a few centuries of global populations that number in the billions.

A few centuries? Like... four?

Technology marches on, progress gets ever faster. We're advancing our capabilities so much more rapidly today than we did in 1623.

Here were some things people didn't know, or didn't know how to do in 1623:

  • Explain gravity
  • Measure temperature or air pressure
  • Pendulum clocks
  • Design or build an engine
  • Measure latitude with a sextant
  • Fly in a hot air balloon. Or plane.
  • Take photographs
  • Make propellors

That gets us about halfway to the present.

Now, think of everything invented since then.

And consider progress is increasing.

Being worried about any problems that will occur multiple centuries from now (and are not growing/lagging issues like climate change) is literally crazy.

Will they work out how to cost-effectively harvest phosphorous from human poop before 2450? Yes. And if by some miracle they have not, they'll do it expensively.

8

OblongRectum t1_j5wy2xb wrote

>Explain gravity

Quibbling here, but scientists can't explain gravity, they can only explain what it does. They still dunno why

13

Deleena24 t1_j5xay43 wrote

Leading theory is that gravity is a result of warping the fabric of space-time. The larger the mass the larger the warp. At least that's what Einstein proposed.

7

Prying_Pandora t1_j5xx7uu wrote

Like a bowling ball in the middle of a trampoline.

3

Deleena24 t1_j5y2r7c wrote

Yes, basically. The bigger the ball the more the trampoline sags/warps, and the closer to the ball the deeper the warp (the closer to the object the more influence/strength it's gravity has.

Except the trampoline would exist in every direction instead of a flat plane.

2

clampie t1_j5yx0mc wrote

Or a cat between the sheets while you're making the bed.

2

AftyOfTheUK t1_j5xg8my wrote

>Quibbling here

I love a good pedant.

Should have been "Accurately describe and model gravity's effects"

6

DraziBlack t1_j5x185b wrote

I've heard that by 2240 we aren't even going to need to poop anymore.

5

AthKaElGal t1_j5xk9y3 wrote

that's very possible. nanobots could recycle our body's waste products.

2

Girafferage t1_j5xgg52 wrote

We already are recycling human waste to fertilize crops. It's actually kind of a problem because the drugs people take also go with that waste into the fertilizer and end up in people's food.

It's literally the only reason I buy organic for vegetables that grow underground or on the ground. Organic foods cannot be grown with fertilizer from human waste.

2

GeekSumsMe t1_j5xjky3 wrote

Yes, this is an issue with respect to biosolids (human poop compost). It is not an issue when the P is harvested more directly. Look up struvite harvesting via waste water treatment in Google Scholar. The science is interesting and the tech is there.

3

Girafferage t1_j5xjrwp wrote

Will do! And yeah, taking components out of the waste seems like the only safe and reasonable way to go. Hopefully we make something out of it.

2

Chrisf1020 t1_j5y9c00 wrote

Here is a link for struvite harvesting. The process is very energy intensive: https://www.sciencedirect.com/science/article/abs/pii/S0921344919303246

On the subject of biosolids reuse: Last year, Maine became the first state to ban the land application of biosolids —— not due to pharmaceuticals and personal care products (PPCP), on which little research has been done, but due to per- and poly-fluorinated alkyl substances (PFAS) a.k.a. “forever chemicals”. This should be your main concern regarding the reuse of biosolids for agriculture, as PFAS bioaccumulate in your body.

2

Girafferage t1_j5y9zqs wrote

It would be, except there isn't rain anywhere on the entire planet that doesn't already contain dangerous levels of it. And eating 1 wild caught fish is just as bad as a month of drinking contaminated water.

https://www.usatoday.com/story/news/world/2022/08/13/rainwater-unsafe-drink-pfas-chemicals-study/10317424002/

https://phys.org/news/2023-01-wild-fish-month-tainted.html

Good on Maine though for actually trying to do something at least. We really need a system to remove them from the environment at this point, and maybe hold the companies that made these chemicals and knew about these negative effects accountable. There haven't been a ton of study's on the pharmaceuticals in waste fertilizer from humans, but the ones that have checked the contents of different brands aren't optimistic. Dangerous levels of a multitude of drugs, some that women aren't even supposed to handle period.

2

Chrisf1020 t1_j5yiyc2 wrote

>It would be, except there isn't rain anywhere on the entire planet that doesn't already contain dangerous levels of it.

Just because it is already everywhere, doesn’t mean it is less dangerous/concerning than PPCP (though it obviously doesn’t mean the contrary, either. Need more research). Keep in mind that the bar for ‘dangerous’ has been lowered so significantly that all water on the planet is basically guaranteed to contain dangerous levels of PFAS at this point. One of your linked articles mentioned it, but last year the EPA also set new health advisories for the two most common PFAS (PFOA and PFOS) at unconscionably low levels: 0.004 ppt for PFOA and 0.02 ppt for PFOS. These values take into account lifetime exposure and bioaccumulation. The previous advisory was 70 ppt for both, so the new advisories are 17,500x and 3500x more strict, respectively. EPA considers these levels “near zero” and admits they are “below EPA’s ability to detect at this time,” meaning the safe level of consumption for those two chemicals is practically zero.

>Good on Maine though for actually trying to do something at least. We really need a system to remove them from the environment at this point, and maybe hold the companies that made these chemicals and knew about these negative effects accountable.

Thermal destruction seems to be the most promising at the moment. Carbon-Fluorine bonds are very hard to break. It requires temperatures around 1000 °C, so very energy intensive. Time and turbulence are also factors in destruction. Typical sewage sludge incinerators (most sludge is incinerated in my state) do not reach these temperatures, however.

>There haven't been a ton of study's on the pharmaceuticals in waste fertilizer from humans, but the ones that have checked the contents of different brands aren't optimistic. Dangerous levels of a multitude of drugs, some that women aren't even supposed to handle period.

I’d be interested to read those PPCP fertilizer studies if you have links. I work in the wastewater industry if that wasn’t already obvious, so I’m always trying to learn more.

2

mech_man_86 t1_j5xcrr4 wrote

The problem is, it all ends up in the deep ocean.

2

Mafik326 t1_j5y6880 wrote

I wish we were as willing to spend on infrastructure with good societal goals as we are on roads.

2

TK-741 t1_j5yr50y wrote

“Have the tech” is a bit of a misnomer.

It costs billions of dollars to make marginal improvements in P removal. Financially it makes more sense to pay farmers to employ more sustainable fertilizer application practices.

Even then, excess P in groundwaters is going to lead to persistent problems for decades to come even if we stopped all new discharge of P from point and non-point sources.

A wicked problem if ever there were one.

1

kimthealan101 t1_j5xexfw wrote

You can't use human waste to feed crops intended for human consumption

0

Twirdman t1_j5xn1wd wrote

Yes we can. We cannot use untreated human waste to feed crops intended for human consumption but that isn't the same thing.

5