Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Egypt has managed to plant trees in the desert using wastewater

al-monitor.com

Post reply on HN
Print view View original

91–100 of 123 posts

Re: Egypt has managed to plant trees in the desert using wastewater

#91

Post by dmos62 »

jackmoore wrote: post #82
htnsao wrote: post #78

Earlier quoted context omitted.

You missed the part about only needing to fill it once.

I don't follow this

Here's an interesting case study about a plantation in a dry ski resort. It has more info, which is otherwise a bit hard to find: https://www.youtube.com/watch?list=PL5MDcgMmY2CXV3x-v0KCjMd1...

Notice, that it's a playlist with a bunch of these case studies.

The device displayed in the video (the company makes a few different ones) didn't require watering at all, because it collects dew. It's also biodegradable, so there isn't a cleanup cost. They also provide physical protection for the sapplings, which can be important. It seems to add up to very high survival rate in tough environments.

Edit: here's a brochure explaining the technology: https://issuu.com/groasis/docs/brochure_eng_2

Re: Egypt has managed to plant trees in the desert using wastewater

#92

Post by headmelted »

nextaccountic wrote: post #79
headmelted wrote: post #28

Is this a good thing? I mean it’s certainly interesting but as others have pointed out the desert is a natural ecosystem and it makes a lot more sense to reforest areas of previous growth than doing this. That’s not really my problem with it though. Surely from a climate change perspective this is really just introducing a fairly large carbon sink that will eventually release the carbon in short order if the irrigati…

Yes, it is. The Sahara was green some 15000 years ago https://en.wikipedia.org/wiki/African_humid_period

That’s exactly my point though. From the link:

“Even if humans stop emitting greenhouse gases today, these gases would still be elevated by the year 12000.”

Creating a temporary carbon sink in the form of a desert forest helps in the short term, but is not negative carbon. It’s net carbon neutral.

Genuinely being “green” in this instance requires sequestration of the existing gas from the atmosphere.

Re: Egypt has managed to plant trees in the desert using wastewater

#93

Post by panny »

danans wrote: post #2

It's not clear to me what the source of water is relative to the size of the forest, because IIUC, in dry regions like Egypt (and California, Israel, etc), unless you use drip-irrigation with targeted crops (which won't grow a forest), agriculture requires a huge amount of water compared to domestic water consumption, so the wastewater stream from the latter intuitively can't be nearly enough to support a forest. Per…

The point is to get rid of the wastewater safe/cheap/efficient rather than grow the forest. Water consumption isn't the concern. They certainly wouldn't be doing drip irrigation with wastewater because wastewater would clog the equipment. Evaporation is expected and desired. Treated human waste is full of pharmaceuticals and phosphates from detergents. It should not be used to grow food unless it is feed for animals. Drainage is a concern on sandy soil. You wouldn't want these sites anywhere near your groundwater supply. You can't dump phosphates and nitrogen in your rivers because the result is algal blooms -> depleted oxygen -> fish kills and really toxic shit like Pfiesteria, which can give you headaches, cognitive problems, and nerve damage just from standing knee deep in the water.

Really, how well the forest grows is beside the point. They're doing this to dispose waste water. If they can make a tree crop to offset costs a bit, then great. The "climate change" angle is lipstick on the pig.

Re: Egypt has managed to plant trees in the desert using wastewater

#94

Post by krab »

jackmoore wrote: post #81
htnsao wrote: post #39

There's a better way to do it.. Trees can be planted in deserts without irrigation using technology developed by a Dutch company called Groasis [0]. They have also recently come up with a new version of their Waterboxx that can use any kind of wastewater to plant trees, even sea water. [1] Looks like it works via solar condensation which then wicks into the soil so the roots can follow it down to the deeper capillary…

You'd have to constantly refill it, which would still require irrigation for transport. Instead of centralized distillation plus transport, you have distributed mini distillers at point of consumption plus transport. This doesn't seem special, what am I missing?

The distillation is powered completely by the solar heat. You can also use quite low tech transportation because you do it only once in a while.

Re: Egypt has managed to plant trees in the desert using wastewater

#95

Post by ClumsyPilot »

andai wrote: post #63
01100011 wrote: post #35

Earlier quoted context omitted.

Your water needs might drop significantly once the forest is established. Depending on the trees, the established canopy might drop the evaporative losses dramatically.

Maybe they emulate a canopy with some kind of tarp while the trees are growing?

I think you are looking for a greenhouse, all evaporated water will condence inside and you will need dramatically less for your plants

Re: Egypt has managed to plant trees in the desert using wastewater

#96

Post by ClumsyPilot »

daniellarusso wrote: post #52
Mediterraneo10 wrote: post #21

Earlier quoted context omitted.

Already there is a backlash against sea salt in the artisanal-product-buying community because it has more microplastics than certain mined sources.

I have suspected this, but have not read any specifics. I can actually recommend this, which should not have the micro-plastic issue: https://www.jqdsalt.com/our-salt/ “Our brine is naturally sourced from an ancient, untouched sea called the Iapetus Ocean (predating the Atlantic) trapped below the Appalachian mountains. Our salt is free of contaminants and heavy metals that may be found in other oceans. Gleaned from…

'normal' salt mined from the ground don't have microplastics in it,

Re: Egypt has managed to plant trees in the desert using wastewater

#97

Post by londons_explore »

ClumsyPilot wrote: post #95
andai wrote: post #63

Earlier quoted context omitted.

Maybe they emulate a canopy with some kind of tarp while the trees are growing?

I think you are looking for a greenhouse, all evaporated water will condence inside and you will need dramatically less for your plants

You still need more than you'd expect. Plants need CO2 to live, and with CO2 at just 0.04% of atmospheric air, you need to let a lot of air (and accompanying water vapour) in and out of your greenhouse to let the plants have the CO2 they need.

Or you burn natural gas to produce CO2 (and some water), but then your carbon sequestration goals go up in smoke...

Re: Egypt has managed to plant trees in the desert using wastewater

#98

Post by farseer »

danans wrote: post #9
soperj wrote: post #4

Earlier quoted context omitted.

That's the current forest that was started in 98. The one that they're starting now is 100 million hectares (1 million sq km).

That is 380 times larger. Unless they are massively underutilizing the current wastewater stream, they need to multiply the irrigation water use efficiency that much, unless they think of forest is going to alter weather systems in such a way that brings rain to the area.

Is there any man made forest on Earth that started to induce rainfall?

Re: Egypt has managed to plant trees in the desert using wastewater

#99

Post by farseer »

dmos62 wrote: post #91
jackmoore wrote: post #82

Earlier quoted context omitted.

I don't follow this

Here's an interesting case study about a plantation in a dry ski resort. It has more info, which is otherwise a bit hard to find: https://www.youtube.com/watch?list=PL5MDcgMmY2CXV3x-v0KCjMd1... Notice, that it's a playlist with a bunch of these case studies. The device displayed in the video (the company makes a few different ones) didn't require watering at all, because it collects dew. It's also biodegradable, so t…

Dew collection at night and massive evaporation of the Sahara during daytime. Not sure if this would be enough to sustain a medium sized tree. Whatever works in Netherlands may not work in Egypt.

Re: Egypt has managed to plant trees in the desert using wastewater

#100

Post by alex_duf »

andai wrote: post #65

The UN's Forestry Department has a fact sheet here (pdf) with some annotated satellite pics showing the layout and species. http://www.fao.org/forestry/35800-094f4eedb0c86a4a33be1a3d90...

Thanks, I was trying to spot it from satellite pictures and it doesn't quite seem to match the ambitious videos that are on the https://www.greatgreenwall.org/ website

I really like the idea though, I hope it goes through

Post reply on HN