The idea is to take processed wastewater, from large coastal cities, and route it inland to arid areas instead of simply dumping it into an ocean that doesn't care either way.
"Coastal" because the loss of freshwater influx won't affect a precipitation cycle that's usually based on evaporation from the ocean; "large cities" because their harbours are already screwed up. This idea will, in fact, unmess them to a certain degree; "processed" because you don't want to toss all that bacteria into groundwater.
The effluent is pumped to an arid area where it fills their local water tables. You could even make new lakes.
As an example, New York's wastewater treatment plants process 1.3 billion gallons of wastewater each day: almost 2 cubic kilometres of unsalinated water per year that gets dumped into the Atlantic Ocean.
And that's just one city.-- FlyingToaster, Dec 27 2010 A desert by any other name... Tundra_20TreelineFor this one we can use almost-unprocessed wastewater, to provide nutrients as well. [FlyingToaster, Dec 27 2010, last modified Jul 21 2011] Petroleum grass (formerly known as "rapeseed") http://www.reggie.n...09/rapeseed-fields/Flower power baby! [doctorremulac3, Jun 11 2012] (Hebrew) Tel Aviv mayor promises to jump into renovated Yarkon river http://www.youtube....watch?v=VGZD573J5CcWhich he actually did a year later. [pashute, Jun 30 2013] Here he is jumping http://www.youtube....watch?v=rwkGiLwiLlc [pashute, Jun 30 2013] Recycling wastewater in Israel http://www.jpost.co.../Wastewater-wonders [FlyingToaster, Jul 01 2013] Perth http://www.watercor...water-replenishmentnice website: links to their desalination projects and other interesting stuff. [FlyingToaster, Jul 10 2013] Of course [+]-- BunsenHoneydew, Jan 02 2011 I ruled out buying property in what I thought was arid land somewhat close to El Paso when my research turned up it was a dump site for New York City's wastewater sludge (distilled sewerage, if you will).
There is no more cheap land, even when times are tough, I guess.-- Zimmy, Feb 10 2012 I'm not up on the efficacy of bacteria but plain old human-waste sewage should be okay after a few years.
Makes lousy fertilizer. But better than nothing.
The problem would be with heavy metals from industrial waste.-- FlyingToaster, Feb 10 2012 Another problem is all the medication sooooo many people are taking these days. Much of it doesn't even get absorbed, and sewer water has a lot of drugs in it these days.-- Psalm_97, Feb 11 2012 I'm pretty sure most medications will break down pretty quickly in the soil - they're all complex organic molecules (and yes, I know about salmon becoming olympic cyclists because of the hormones in effluent, but that's because there's continuous inflow that reaches a steady state).-- MaxwellBuchanan, Feb 11 2012 What [FlyingToaster] and [MaxwellBuchanan] said. Toxic elements are the really intractable problem. Once actual ingots of lead, arsenic, et al. start coming out of sewerage works, it will be a problem solved, but until then, little cat Z's hat conceals not Voom, but a Broom, and we're running out of rug.-- spidermother, Feb 11 2012 I think the problem here must be the expense of pumping and lack of markets to offset that expense. For example, why not send Los Angeles treated wastewater to refill poor Mono Lake? Or San Diego's to the Salton Sea? Because who would pay for it?
If agricultural users no long had subsidized water, they might be willing to pay enough for this treated water to justify its transport over long distances.-- bungston, Feb 14 2012 As it happens, I was briefly involved in a trial of a version of this idea. The main sewerage treatment works for Adelaide (a coastal city) is 50 km or so inland, in a rather arid area (like most of the state), so a lot of the pumping work has already been done. The land is also cheap, because no-one wants to live next to a sewerage works.
The trial involved a woodlot, close to the sewerage works, irrigated with partly treated effluent (basically, what's left after the sludge has been removed). As I recall, the heavy metal levels were such that the land would be rendered unfit for agriculture (essentially forever!) after a mere hundred years or so of continuous application. But the trees were "leaping out of the ground", to quote another observer.-- spidermother, Feb 14 2012 //SO//?
I don't think laundry bleaching agents are particularly polluting. They do contain a lot of sodium, which is a problem on land with salinity issues, but they're not nasty in the way chlorine bleach is.-- spidermother, Feb 14 2012 Like [sm] said, there are some examples of it around. However, in my experience, this has only been done for very small systems because disposing of a significant volume of treated sewage is very expensive.
The same outcome (increasing the security of supply of potable water) is achieved much cheaper by sewer mining (treating sewerage until it is clean enough to drink and pumping it back into the water system - the Sydney example is particularly good).
In response to the addendum, that's a pretty big pipeline you're suggesting. DuckDuckGo (it's a verb by now, shirley) "Combined Sewer Overflow volume" and have a look at the amount of water involved. Still, nothing's impossible for a 'baker.-- methinksnot, Feb 14 2012 On the other hand, if the heavy metals were removed at source, sewage could be discharged onto land with far less processing than that required to make it safe to discharge into waterways or the sea - which could swing the cost in favour of this idea.
(Aside: Toowoomba and Goulburn looked into the "sewer mining" option; residents opposed it, saying things like "we don't care what the science says, we won't drink sewage". Instead, they continue to discharge partially treated sewage into the Murray River. Guess where Adelaide gets much of its drinking water? Thanks, guys.)-- spidermother, Feb 14 2012 The stuff that comes out of big city treatment plants is potable... ish. Barring the initial capital cost of a pipe, I don't see pumping or maintenance as being particularly onerous, financially.
I can't remember offhand what they do in large installations about dissolved heavy metals, though some smaller installations use plant-life to sequester them.-- FlyingToaster, Feb 14 2012 //use plant-life to sequester them// i.e., sweep them under the rug.
The confounding of nutrients and heavy metals may be one of the really big problems we're setting up for ourselves - up there with peak oil and global warming (pace sceptics).-- spidermother, Feb 14 2012 //under the rug// not really: burn off the vegetation and you're left with heavy metal laced ash. § x1-- FlyingToaster, Feb 14 2012 ... which creates a much less conspicuous bulge. Sorted!-- spidermother, Feb 14 2012 /leaping out of the ground/ nice!
Heavy metals should not be a big concern for fiber crops or forestry products.-- bungston, Feb 14 2012 That's precisely the attitude I find so alarming! Heavy metals never break down, and have many paths into humans - inhaling dust and generally playing outdoors is particularly efficient for poisoning children; and permanently contaminating land because it won't affect us in the short term is short sighted.
On a smaller scale, I once had a bathtub full of somewhat lead-contaminated soil. A friend suggested I put it on a part of the garden where I didn't intend to grow vegetables, which I likened to exterminating all the Jews in a place where you didn't intend to eat a bagel. (I took it to the dump, which seemed like the least worst solution.)-- spidermother, Feb 14 2012 ^^ Put it in a pressure vessel with some water and heat the thing up a bit past the melting point of lead. The boiling water will churn it and after awhile you should end up with the lead on the bottom.-- FlyingToaster, Feb 14 2012 ^^ Thanks, although I prefer the term "extreme analogy".
^ //^^// They've gone quantative now! Cool. Alternatively, I could add a generous amount of mercury, and recover some of the lead as amalgam.-- spidermother, Feb 15 2012 //Alternatively, I could add a generous amount of mercury, and recover some of the lead as amalgam.//
Mmm. mercury contamination is so preferrable to lead.
... If you can concentrate the heavy metal enough, the material is effectively ore and becomes worth processing.
//On the other hand, if the heavy metals were removed at source, ...// This would be the ideal solution - remove the externalities from the waste disposal. Get the producers to process at the outflow, before it gets diluted to unmanagability.-- Loris, Feb 15 2012 She swallowed the mercury, to sequester the lead, I don't know why she swallowed the lead. I think she's dead.-- spidermother, Feb 15 2012 ^[+]-- mouseposture, Feb 15 2012 Spidermother,
In the Yarkon Sewage Treatment Center they added a large constructed wetland post processing project, and found that all medications - the last problem left after the treatment, were totally broken down, with the water being designated as clearwater!
It was tested not only by scientific analysis of the water itself, but also long-run analysis of of fish and plants growing in the output water.
Creating such a project in a desert area is not expensive at all (the construction is done with no moving parts, and is quite simple).
BTW, in Israel we are up to 92% reuse of all sewage water!-- pashute, Jun 04 2012 [+] for SpiderMothers witty rhyme-- PainOCommonSense, Jun 11 2012 So let me get this straight, you can use the water for non-edible agricultural products right?
So have this water go into the desert to grow rapeseed or canola oil for biodiesel. Aren't there enough plant nutrients in the water to make these crops thrive? As nasty as they might be from a human consumption standpoint if you're just making biodiesel out of it that's not an issue.
Somebody has to have thought of this no? Seems like a great idea.
Did a little search and yes, it's been proposed, and the numbers look doable. Sounds like you build an aquaduct to the desert, buy some biodiesel fueled farm equipment and get busy putting people to work creating renewable energy. Am I missing something?-- doctorremulac3, Jun 11 2012 [doc-e] the idea as such is to shift the wastewater after it has been treated.
The target donor-cities are those on the coast, which environment won't be changed by removing water. By contrast, inland cities' locale may be affected by the water loss to their own water tables.
That's the simplest idea of course: just hook a u-bend pipe onto the end of a coastal treatment plant and start pumping. So what goes into the pipe is almost good enough to drink and, after it has soaked into the ground at the other end and/or been exposed for awhile to the environment, would be pretty reasonable freshwater.
Another idea would be to move the untreated water, processing it at one inland spot (which property values would plummet somewhat). But that's more complex: nasty things happen when crap gets into the water table.-- FlyingToaster, Jun 11 2012 I could be wrong, but I don't think there's any difference fresh water wise between coastal cities and inland cities unless you're talking about the coast of a fresh water lake. I assume the vast majority of aquifer or reservoir replenishment comes from rain no matter where you are. Maybe waste water figures into it, I don't know.
But either way, grey water as this stuff is called could be a valuable commodity for land reclamation for biofuel crops since there's no toxicity issues.
Does seem a shame to just throw fresh water away. Especially nutrient rich fresh water that might be safe enough for non-consumable crops such as biofuel seed crops.-- doctorremulac3, Jun 11 2012 The stipulation "coastal" is because quite a few inland precipitation cycles are locked, ie: the rain that falls mainly on the plain also evaporated mainly from the plain, so if you take water away there won't be any water left.
While ocean-coastal cities would take from a local freshwater aquifer, that aquifer is being replenished from rain which evaporated from the sea, said sea not going anywhere anytime soon.
That being said there probably are some cities where the wind always blows out to sea, and some cities a couple hundred miles from the ocean where rainfall is purely ocean based.
Re: "graywater", the stuff coming out of large modern treatment plants is pretty "white"... might want to skip the usual last step, adding chlorine, to save wear and tear on the pipes. Some people might object to human-based sludge, but I don't think anybody'd have anything to say about last-stage effluent (the sludge and grease having been removed several stages previous).-- FlyingToaster, Jun 11 2012 Yea, so grow rapeseed with it and put the oil from the harvested seeds in cars.
Might want to look into a better name for the plant while we're at it. Petroleum grass or something.-- doctorremulac3, Jun 11 2012 'cording to Wikipedia, "rapaseed" is acceptable. Canola is one of the varieties.
The nomenclature is from the Latin for "turnip".-- FlyingToaster, Jun 11 2012 They'd be pretty too. (See link)-- doctorremulac3, Jun 11 2012 [+] though in Israel 90% of wastewater is treated and RETURNED to the water system.
At the Yarkon treatment center, it is treated a second time (after the full treatment center releases the water) in constructed wetlands, and then sent to back to the restored river, where wildlife and marine life has been restored. It is then pumped up towards the sea and used for irrigation.-- pashute, Jun 30 2013 You could do twinning, with London's waste water being swapped with Leipzig's or something like that.-- not_morrison_rm, Jul 01 2013 <link to J-Post article>
Tel Aviv's wastewater recycling system is pretty well the idea, having the major earmarks of being both a large city and on the ocean(ish), ie: both local and "downstream" environments aren't negatively impacted by water taken out of the cycle...
... arguably making this post advocacy though, also arguably, not WKTE.-- FlyingToaster, Jul 01 2013 Perth, Western Australia, is thinking of going the same way soon - that is, waste water back into the water table.-- pertinax, Jul 08 2013 //Perth// According to their site <link> they've had a pilot project going for the last few years... mentioned something like 30,000,000 litres a year returned to the deep aquifer they draw from. (Great website but it's still mostly PR: 30,000,000 litres a year isn't even a litre per second)-- FlyingToaster, Jul 10 2013 Maybe the pilots couldn't pee any faster.-- pertinax, Jul 10 2013 Anybody know the pilot's pee output numbers?-- not_morrison_rm, Jul 10 2013 random, halfbakery