Rocket Thrusters Used To Treat Sewage

Zothecula writes "Rocket engines are generally not thought of as being environmentally-friendly, but thanks to a newly-developed process, we may someday see them neutralizing the emissions from wastewater treatment plants. The same process would also see those plants generating their own power, thus meaning they would be both energy-neutral and emissions-free. Developed by two engineers at Stanford University, the system starts with the formation of nitrous oxide (N2O) and methane gas — something that treatment plants traditionally try to avoid."

Comments

I don't understand

[Monkeedude1212]

Is it like... Rocket science?

Re:I don't understand

[GameMaster]

Specifically, it's shitty rocket science.

Re:I don't understand

[Anonymous Coward]

Better. It's Rocket Science on Jenkem!!

I know just the place to test this...

[CeruleanDragon]

On a hot day the Lowell, MA water treatment facility can me smelled for a good mile plus in every direction, strongly. And there's a low-incoming housing complex right next to it. How those poor people can live there is a mystery. Although I guess I just answered that. Ok, so not a mystery.

At any rate, it would be a great candidate for this sort of technology. And I wonder how this tech could be applied to space travel and such self-contained environments or poor areas such as submarines, underwater facilities, small third world countries/towns, etc.

Re:I know just the place to test this...

[Kepesk]

And if rockets can be used to solve this stinky problem, what can't they do?

Can't get into the pickle jar? Rockets!

Neighbor's cat keeps leaving presents in your yard? Rockets!

Excessive cell phone charges on your bill? Lasers! Then rockets!

Re:I know just the place to test this...

[Wyatt Earp]

Because after a few minutes you just won't smell it anymore.

I've worked in a sewage treatment plant doing process pipe design. You don't smell it after about 5-10 minutes.

Re:I know just the place to test this...

[danbert8]

Yes, luckily H2S numbs your sense of smell first... (note this is sarcasm, while H2S is the "rotten egg" smelling chemical, it can kill you pretty quick)

Re:I know just the place to test this...

[Sulphur]

How do you associate incoming with rockets?

Re:I know just the place to test this...

[hitmark]

got to love how the brain takes away unpleasant, but not directly harmful, experiences.

Re:I know just the place to test this...

[Anonymous Coward]

Then grab 2 beers and jump.
http://www.latenightwithjimmyfallon.com/video/jet-blue-song-the-ballad-of-steven-slater-81010/1243478

Re:I know just the place to test this...

[davester666]

Yes, I'm sure they will prefer the roar of a bunch of rocket engines 24/7 over the smell of sewage.

Re:I know just the place to test this...

[CeruleanDragon]

Can't be any worse than the roar of a few Cisco Catalysts and a few dozen servers, can it? Which would you prefer? You can turn up your TV or put on headphones, it's a little less comfy to walk around with nose plugs all the time. ;)

Re:I know just the place to test this...

[CeruleanDragon]

These scenarios sound like they should all end in... profit!

Read about it somewhere...

[Cyberax]

Ah! I remember reading about the same idea in Stephen Baxter's "Manifold: Time" - http://en.wikipedia.org/wiki/Manifold:_Time

It has not ended well there :)

Why not a fluidized bed?

[vlm]

Why all the complication of a rocket engine (aerodynamic flow, high thrust to weight ratio, ignition problems, injector stability/howling issues, injector clogging issues, high pressure fuel pumps) when they could just pipe it into a nice boring fluidized bed?

Sounds more like a stunt, to "get kids interested in science", than a solid technical engineering decision.

Re:Why not a fluidized bed?

[kg8484]

Probably because they approached the problem from the other direction (e.g. not looking for something to do with all that N2O, but looking for a source of the gas).

Brian Cantwell, a professor of aeronautics and astronautics at Stanford, has created clean-burning rocket thrusters that run on N2O. "We wondered whether nitrous oxide could be exploited as an emissions-free source of energy," Cantwell said. "Since the product of the decomposition reaction is simply oxygen-enriched air, energy is generated with zero production of greenhouse gas. But first we needed to find a cheap, plentiful source of nitrous oxide."

That source, of course, would be the wastewater treatment plants.

Seems like Cantwell developed the N2O rocket first and then looked for where to get fuel. He got in touch with Craig Criddle, "a professor of civil and environmental engineering and senior fellow at the Woods Institute for the Environment at Stanford," and this idea was born.

Re:Why not a fluidized bed?

[bluefoxlucid]

Because they're changing the chemical environment to cause a lot more methane and N2O production. Then they burn the methane; but they don't have a way to deal with the N2O, so they use a different type of combustion system (a rocket booster) to burn that and emit oxygen and nitrogen gas (2N2 + O2). Normally, they add excess oxygen to the waste to produce N2; but the bacteria that fixate methane then get less fuel, and make less methane. So this process allows them to produce more fuel from human waste while lowering N2O emissions.

Re:Why not a fluidized bed?

[vlm]

but they don't have a way to deal with the N2O, so they use a different type of combustion system (a rocket booster) to burn that and emit oxygen and nitrogen gas (2N2 + O2)

Still doesn't answer my question of why a rocket?

Chemical oxidation is chemical oxidation no matter if you react it in a catalytic chamber, a boring old flame, a fluidized bed, or a rocket engine. They picked a rocket, which seems like a pretty stupid idea.

A rocket engine : Has a high thrust to weight ratio so it flies further but is an unholy PITA to design, Operates at high pressure AND temperature so you need exotic materials (either one separately is way simpler than both simultaneously), rockets have all kinds of terrible flame stability problems unless the injectors have a pretty high delta-p so you need to pressurize the heck out of the fuel and use tiny little easily clogged injector nozzles, output extremely high velocity exhaust (louder than hell). Oh and there are also multiple ignition problems such as "hard starts" when the fuel pools before ignition and blows the chamber like a bomb, and various sequencing problems (gotta spin up the oxidizer and fuel turbopumps at the same rate), and finally most non-hypergolic systems have serious issues with multiple restarts.

N2O will just burn, so why not do something way more appropriate like flow it into the intake manifold of a fuel injected IC engine hooked up to a generator, or "just freaking burn it" in a simple burner, or a somewhat more fancy fluidized bed?

So I ask again, is there any reason to use a rocket engine other than "gee whiz cool"?

Re:Why not a fluidized bed?

[vlm]

(e.g. not looking for something to do with all that N2O, but looking for a source of the gas).

The problem is that rocket fuel grade N2O (few particulates to clog the injectors, few corrosives, low water content, low contaminant content such as CO2, N2, etc) is frankly pretty cheap, about twice the cost of cow milk per volume.

Even if N2O from sewage is magically "free" (don't they need enclosed tanks instead of open top tanks?), the filtration and purification plant is going to make it more expensive than the industrial product.

So its all just a stunt.

Finally I laughed at the whole concept of it being an "emissions free source of energy". If it takes 10 calories of petroleum to produce 1 calorie of edible food, the end to end efficiency must be lower than 10%, probably far, far lower. If you could extract much energy from poop your body would have evolved to extract it. We're actually darn near 100% efficient at simple sugars, for example, somewhat less so for indigestible fiber of course. Anyway its either an irrelevantly small source, or requires a ridiculous amount of primary energy (petroleum). Its a rube goldberg machine to extract a little extra energy from petroleum and sunlight.

Re:Why not a fluidized bed?

[bluefoxlucid]

Rate of burn, burn characteristics, temperature, ability to direct output through a turbine (you wouldn't just pipe this into a chamber and ignite it...). Rocket engines consume fuel very quickly, and give a high amount of thrust. They're also the most energy efficient jet engine design as a group.

Re:Why not a fluidized bed?

[bluefoxlucid]

In ancient religions like Hindi and Taoism, they believe that there is a source of energy to all life, accessed spiritually by the body and by breathing. Your body blocks most of it, because you need very little to live; and by certain exercises, you can access much more of it.

Do you honestly think that your body uses every ounce of energy it can get? If there's an infinite life force to access, your body doesn't need to access it at maximum burn. Similarly, with so many plants and bacteria and animals and all the other shit going on in the world, our bodies would have developed with a chemical process to reduce sugar to CO2 and H2O, yes; but why, when running just fine on that small bit of energy, would our bodies evolve to process carbon-rich complex fatty acids into methane and N2O and then slow-burn it metabolically? Especially when we can always acquire a hundred times more food than we need?!

I mean, it's not a convenient process at hand; but it's not a difficult process. A septic system works by rending down waste into liquid and methane gas simply by allowing bacteria to gather 100% of their life-sustaining energy off it. You're not shitting a drained block of inert material.

Re:Why not a fluidized bed?

[Captain Centropyge]

Have you seen any nitrous oxide engines being produced..? The only engines I'm aware that use NO2 are the ones that inject it along with gasoline (i.e. rice burners, drag racers, etc.).

My assumption is that they want a rocket to increase consumption of the NO2, which a rocket would burn considerably faster than a simple internal combustion engine. An NO2 ICE still needs to be designed, which will cost money. And a rocket would burn much hotter, allowing for faster use of energy. You could use this to generate steam or something. I'm not saying it's the most efficient method, but things seemed to fall into place. Plus, if necessary, they could bottle and store the NO2 for later use in actual rockets, I suppose...

Re:Why not a fluidized bed?

[blair1q]

In ancient religions like Hindi and Taoism, they believe that there is a source of energy to all life, accessed spiritually by the body and by breathing.

They got the breathing part right, but you have to wonder how they missed the role food plays in it.

Or maybe they couldn't care less about reality and were trying to find out who's gullible and who isn't.

Re:Why not a fluidized bed?

[bluefoxlucid]

They got quite a bit of the framework right. When you exhale, your breath is still usually pretty oxygen-rich. 21% oxygen going in, 4-5% less coming out. So yes, your body has access to a large amount of life-giving oxygen with each breath, and only uses a fraction of it (20-25% of the available stock in this case).

They also believed that all life requires balance. Overdosing on oxygen, water, vitamin C, and the like seems silly; but you can do it. Hell, you can overdose on exercise. Gluttony and anorexia. Too much work and not enough play, too much play and not enough work. Firmness versus fairness (abusive husband/parent versus spineless coward).

It's amusing that when comparing "materialism" versus "spirituality," people decide that they're "using reason" and entirely reject spirituality as some sort of voodoo fluff for idiots. Then they struggle to put a lot of scientific data in their head about how each individual thing needs moderation, regulation, and balance; while the spiritual disciplines they've chosen to ridicule have said so much for over 5000 years, just without addressing each individual type of grain and each type of biologically useful molecule (vitamin, mineral, fats, etc).

A lack of balance in this way creates the blind: people who reject science in favor of arguing the most ridiculous explanations about why God created everything from specific blueprints; and people who reject anything that doesn't look like a direct cause-effect relationship on physical objects we can see or theoretical ideals that a bunch of university students have theorized "might" exist in their Ph.D. theses.

As a final, mostly irrelevant note, I find it funny that we've scientifically rejected the notion of an "ether" that flows through the entire universe, which we can't detect but which facilitates the movement of light and objects through empty space; yet we theorize that there is some sort of intangible "dark matter" that exists everywhere but which we can't detect except that it supplies mass. Humans are really bad at reason.

Re:Why not a fluidized bed?

[Steve Hamlin]

"but why, when running just fine on that small bit of energy, would our bodies evolve to process carbon-rich complex fatty acids into methane and N2O and then slow-burn it metabolically? Especially when we can always acquire a hundred times more food than we need?!"

Life has NEVER been able to acquire a hundred times more food than we need, except for the last few seconds of history. Life evolved to metabolize anything it could find, because food was ALWAYS scarce.

Life doesn't decide to hide away excess energy in some mysterious spiritual source - sorry. I'm glad you feel more energetic and healthier because of your physical & mental habits, but it's not because you've accessed a hidden source of 'life energy' in the Tao.

Re:Why not a fluidized bed?

[bluefoxlucid]

Life has NEVER been able to acquire a hundred times more food than we need, except for the last few seconds of history. Life evolved to metabolize anything it could find, because food was ALWAYS scarce.

Right, that's why when I bring down a deer I eat it all in an hour and go looking for more. The big issue here used to be refrigeration; and the balance was that we get 75 pounds of meat so we get 75 cavemen together and SOMEBODY finds a deer and we ALL get 1 pound of meat. It's not hard to get 2 or 3 deer in a day (well okay, it's not hard like it's not hard to hit 4 or 5 home runs in a day... you can't do it, but someone whose only food source is what they kill damn well can).

Or maybe large predators like humans and apes evolved when the largest game animal was a squirrel instead of a 2000 pound cow.

And honestly, do you think we need six BILLION of us to perpetuate this species? Pocket tribes of a hundred or so all over, amounting to a few ten millions on the earth, would be stable and food would be plentiful. It's not like we had to compete with Lupinari and talking trees and things with no corporeal form; we had to compete with bears. I can eat a damn bear, the fuck do I care if it's out there hunting my food too?

Aww, shit

[bl8n8r]

The shit will hit the fan with this in numerous ways:
* Most likely raise shit with the EPA
* Environmentalists will shit when they see the carbon produced in the process
* Oil companies will continue not giving a shit about fossil fuel consumption

Re:Aww, shit

[21mhz]

* Environmentalists will shit when they see the carbon produced in the process

These must be quite ignorant environmentalists. The carbon in biomass is fixed for short time periods, so burning it is still carbon-neutral.

Re:Aww, shit

[Locke2005]

Environmentalists will shit when they see the carbon produced in the process
Where exactly do you see the carbon in the chemical N2O? It decomposes into nitrogen and oxygen, or as we Earthlings refer to it, "air"!

Re:Aww, shit

[Captain Centropyge]

N2O doesn't contain any carbon. And as for the methane, when you burn it it gives off water and carbon dioxide. But the vast majority of the combustion reaction creates water. It's far better than releasing methane into the atmosphere without burning it. If environmentalists flip out over this, then fine... just release the methane into the atmosphere and see how happy they are. It's a much worse greenhouse gas than CO2.

Besides, these "self-powered" plants will cut down on energy consumption and very likely offset any CO2 being given off, thereby making the EPA happier than just releasing methane or causing more pollutants from coal-burning power plants.

As for oil companies... who even gives a shit about them, anyway? Why even bring them up? They have no place in this discussion.

Re:Aww, shit

[Captain Centropyge]

He's likely referring to the methane, CH4.

Generate their own power...

[MadKatAlpha]

I'm confused that the article thinks that this is a new concept. Many wastewater treatment plants already make use of the methane gas for on-site power generation. For example, East Bay MUD in California generates 90% of its power requirements at the primary treatment plant.

Re:Generate their own power...

[nedlohs]

Why not read the article and see which part is new.

Re:Generate their own power...

[bluefoxlucid]

Yes, but this process produces more methane along with nitrous oxide fuel. It then adds a method to reduce N2O to N2 and O2, producing more power in the process. In this way, the primary treatment plant produces 110% of its power requirements without increasing emissions simply by adding a piece of equipment the size of a basketball and removing a waste aeration system.

Re:Generate their own power...

[AB3A]

Agreed. Anaerobic digestion usually results in lots of methane.

I do not understand the rocket part. It could be burned to heat a boiler or in a four cycle engine. Why screw around with a rocket? It's not as if the thrust is needed for something.

Re:Generate their own power...

[locallyunscene]

Also, they mention that usually waste water plants try and limit NO2 and methane production by pumping air into the waste water.
The benefits of this approach:
1.) It reduces power needs substantially by removing the requirement to pump air.
2.) It removes more nitrogen from the water in the process.(Hooray for not killing our oceans!)
3.) The thruster can be as small as a basketball and handle all of the gas generated.

You really should just read TFA; it's short, informative, and to the point.

Now they tell me

[drooling-dog]

I just had my main sewer line rooted a couple of weeks ago. If I had known I could use one of my spare rocket thrusters for that, I might have saved a bundle of money...

EUREKA!

[weeboo0104]

FTFA- "the system starts with the formation of nitrous oxide (N2O) and methane gas"

We now have a scientific reason why we laugh at fart jokes.

My nuclear bomb treatment system is better

[elrous0]

Nuclear weapons, while also not generally thought of as environmentally friendly, are remarkably effective at vaporizing large volumes of human waste.

Re:My nuclear bomb treatment system is better

[32771]

Precisely, your suggestion is similar to the Orion project of waste treatment.

Laughing Gas; the solution to all problems

[PolygamousRanchKid]

Developed by two engineers at Stanford University, the system starts with the formation of nitrous oxide (N2O)

Any solution that starts with laughing gas is bound to be a success. And if not, nobody gives a rat's ass anyway. And it will be definitely a hoot and a half for all involved.

Reporter: "Does the sewage plant still stink?"

Resident: "Yeah, but I really don't give a damn anymore."

This could be the beginning of a new age for nuclear energy, if the plants started spewing out nitrous oxide.

Reporter: "Aren't you concerned that the nuclear power plant next door could be the next Chernobyl?"

Resident: "Yes, I am concerned, but with that nitrous oxide pump, who cares?"

Re:Laughing Gas; the solution to all problems

[Anonymous Coward]

Any solution that starts with laughing gas is bound to be a success.

Yup. Why treat sewage seriously when you can have a laugh instead?

I tooted

[rshxd]

I tooted it reeks I jenked

Kind of like...

[Anonymous Coward]

Is this kind of like lighting a fart on fire?

Re:Kind of like...

[KingPin27]

turd bombs!!!

no

[circletimessquare]

it's just a load of crap

East Bay MUD

[Anonymous Coward]

Gee that takes me back. I remember playing East Bay MUD back in the 90s. One of the better MUDs ever imho.

Hidden philosopher/sorcerer's stone?

[aGuyNamedJoe]

From the article:

Usually, air is pumped into wastewater sludge to boost its oxygen content. This promotes aerobic bacteria that convert the sludge’s sugars and other organic materials into harmless nitrogen gas.

...

I presume at least one of those aerobic bacteria has a philosopher's stone in his pocket? Converting sugar, which is a carbohydrate, into harmless nitrogen gas, requires more than mere chemistry.

Struck me there were a couple of similar chemical faux pas(ii? -- how does one do pluralization on such imports?) in the article, making one wonder whether some parts of it can be believed...

Re:Hidden philosopher/sorcerer's stone?

[JSBiff]

Urine is the body's way of disposing of excess nitrogen: Urea (one of the components of Urine) has the chemical formula: (NH_2)_2CO.

Thus, there's plenty of nitrogen in the 'other organic materials' in waste water. Not every hydrocarbon is exclusively hydrogen and carbon - other elements can be present too.

Re:Hidden philosopher/sorcerer's stone?

[DragonWriter]

Not every hydrocarbon is exclusively hydrogen and carbon - other elements can be present too.

Well, sure, if you are inventing your own language. Otherwise, "hydrocarbon" refers to compounds that contain only the elements hydrogen and carbon.

Compounds that include hydrogen, carbon, and other things are not hydrocarbons. (Note that naming conventions may confuse some people on this, as, e.g., compounds containing chlorine, flourine, hydrogen, and carbon are called "chloroflourohydrocarbons", but are not a subset of hydrocarbons but a disjoint set.)

Re:Hidden philosopher/sorcerer's stone?

[JSBiff]

Fine, I screwed up on that statement. Rest of the comment is still valid. Urine in waste water is definitely a source of nitrogen, and is an organic compound.

Re:Hidden philosopher/sorcerer's stone?

[aGuyNamedJoe]

I was aware of the presence of nitrogen in organic compounds (but not, I think, in sugar?).

l may have misunderstood the intent of the original sentence, and simply reacted to the sentence itself. I suspect the intent was to suggest that N2 was created rather than NO2, but "organic matter is converted into harmless nitrogen gas" is not the same as "the nitrogen in organic matter is converted into harmless nitrogen gas" in my usage of the language -- I was, actually, expecting to see CO2 and water in the list, rather than the implied "nitrogen in".

Ah well, modern american english usage appears to include an implied "and whatever" somewhere in almost any sentence.

Re:Hidden philosopher/sorcerer's stone?

[JSBiff]

Ok, this is how I read the sentence: "This promotes aerobic bacteria that convert the sludge's sugars and other organic materials into harmless nitrogen gas."

So, I see that as meaning (sugars + "other organic materials" [Urine and maybe other waste products]) is reacted together/metabolized by the bacteria, producing "harmless nitrogen gas" (as well as other byproducts [I guess that would be your implied 'and whatever'] which the writer doesn't mention because he's not interested in them).

It's just there to get rid of the N20.

[Ungrounded Lightning]

If I read it right, the rocket is just a convenient way to burn the N2O to get rid of it, in the simplest and cheapest way possible. They happened to have this handy rocket engine design and those can be very simple if their controls are well designed.

Getting useful heat out of the N2O is a handy side-effect. (Run a small steam cogeneration system with it if you feel ambitious. Or use it where you need a bit of extra heat.) But the main gain is the enormous extra production of methane, which can already be conveniently utilized by existing systems, now that you can safely get rid of the undesirable byproduct.

Some Details Left Out...

[BJ_Covert_Action]

Well I RTFA and there are some parts of the process that seem lacking. Essentially, a few rocket engineers said they could take the output gas from waste water plants (NO2) and use it to fire and burn a rocket engine. The emissions from the rocket engine would be oxygen enriched air. The power from the rocket engine is supposed to be used to generate electricity for the plant to allow it to continue processing waste water and producing rocket fuel, thus completing a fully self-contained power cycle and allowing the waste water plant to be self-sufficient.

What's left out, however, is how the rocket engines are supposed to be used to generate electricity. Rocket engines are optimized to produce thrust. While liquid engines have turbine machinery in them, this engine would be burning gas with it's own oxidizer in the fuel (NO2). Without the separate fuel and oxidizer plumbing, I am not sure how much pump/turbine machinery would be in the design of the rocket engine. That said, I don't know what kind of spinning motion would be used to generate the electricity for the waste water plant. It would be nice to see some details on how the engine design will be used to actually produce electricity. Don't get me wrong, rocket motors are great sources of energy, but they very rarely, if ever, are used to drive electricity into a circuit. So I am curious if they are simply planning to use the nozzle flame to heat water for a steam turbine, or if they have an internal turbine that is driven by the NO2 (preburn) to drive a magnet surrounded by copper, or if they intend to stick a turbine in the thrust column of the engine (expensive materials).

It's an interesting idea, but some technical details would be nice. Typically rockets attempt to minimize spinning components and, thus, are not nearly as good electricity produces as other types of engines that have spinning components as a fundamental part of their design (ICEs, Diesels, etc.).

Re:Some Details Left Out...

[BJ_Covert_Action]

\ facepalm

Self-edit after rereading, s/NO2/N20/g in my post above.

Re:Some Details Left Out...

[Anonymous Coward]

What if they simply made an 'X' out of metal, and attached a jet engine on the end of each arm. Then they could attach the X to a turbine like a propeller. When the engines were on, the X would spin, turning a shaft.

Would that work? I don't know, just throwing the idea out there.

Re:Some Details Left Out...

[bigrockpeltr]

They could used something similar to a huge turbochager ( which is basically two turbines connected by a shaft) but instead of having the a second turbine compressing air, you could have the shaft connected to an electric motor to generate electricity.

I am not saying this is the best or most efficient way ( it clearly is not ) but this was just as a possible answer to your question.

Re:Some Details Left Out...

[LWATCDR]

Simple they are not really going to use it as a rocket motor.
My guess that is more PR than anything.
Think of it as more of a wielding torch. IE it is going to be a burner.
You but a big tank of water over it and make steam.
steam that turns a turbine.
Or you could use it with a Stirling engine but they cost more than a simple steam turbine.

Re:Some Details Left Out...

[BJ_Covert_Action]

Yeah, the more I read it the more I think you are right. There is nothing "rocket" about the science I would bet. Essentially, I would wager that all they are going to do is burn the N20 like in any other combustible engine and the only "rocket science" that will go into the process will be figuring out proper mixture ratios and flow rates...

Re:Some Details Left Out...

[BJ_Covert_Action]

Not a bad idea, but that's going to have to be a very strong 'X.' Rockets are used for orbital escape for a reason. They provide more thrust than any other engine existing today. Even the small basketball sized ones pack one hell of a punch.

Re:Some Details Left Out...

[jgtg32a]

Windmills, so it can be even more green

Re:Some Details Left Out...

[Raptoer]

It's a lot easier to think of it as a gas powered turbine that doesn't use atmospheric oxygen for combustion. It also seems like they're somehow reacting the N2O itself, instead of using it as an oxidizer for another fuel.

Re:Some Details Left Out...

[LWATCDR]

Well a rocket is really nothing more than a really big burner with a nozzle. So yes I see this as nothing but a big steam kettle.
The other option would be a gas turbine but then you would almost need to have some kind of EGR to make it work. If you add in NO2 to the a standard gas turbine I would think that it would tend push the temps very high and cause NOx creation issues. Using an oxidizer in a gas turbine at sea level would seem to just be a problem in the making.
Unless the CH4 happens to be mixed with a lot of inert gas and maybe even water vapor then it could work but again still way too much trouble.
In this case I say go with the tea pot.

Peeing and Pooping in water is stupid

[Anonymous Coward]

seriously. there's no good way to do phosphorus/nutrient recovery out of wastewater, nor is there a good way to kill pathogens in wastewater (bleach is bad news).

If you're an engineer, stop building rocket engines and work on practical municipal co-composting and urine diversion. Here's some technical literature to get you started:
http://www.susana.org

Similar concept to Nat. Gas. power plants?

[JSBiff]

The article doesn't really explain how they use the methane. Are they burning it in the 'rocket engine' along with the N2O (using the N20 as both a source of energy, and a source of oxygen for combustion of the methane?

Is this in any way particularly different than the numerous existing natural gas electric power generation plants around the world?

Don't get me wrong, this seems like a good idea - use the waste water as a source of energy to run the treatment plant, but, the use of a 'rocket engine' (e.g. gas turbine generator) doesn't strike me as nearly as novel as this article portrays?

Stop joking around!

[Locke2005]

Nitrous Oxide is no laughing matter!

Better application

[PPH]

I preferred the Futurama application of rockets to the garbage problem.

Space 1999

[SnarfQuest]

Aren't all those rocket motors going to throw the Earth out of it's orbit?

Maybe this is the power source for the ramjets on the Ringworld.

Disappointed

[masterwit]

This was entirely not the article I expect, damn.