Student’s six-foot water and solar-powered lens purifies polluted water(buffalo.edu)
buffalo.edu
Student’s six-foot water and solar-powered lens purifies polluted water
http://www.buffalo.edu/news/releases/2014/08/015.html
15 comments
>That is, unless it's not really a technical problem.
It isn't. This has the same problem as all the other solar sterilisers, it says "I'm poor." People are empirically not willing to use these things. You'd probably be better off with a public education campaign to normalise their use, something objectively ridiculous like having middle class families that actually have decent running water doing it, visibily and publicly.
It isn't. This has the same problem as all the other solar sterilisers, it says "I'm poor." People are empirically not willing to use these things. You'd probably be better off with a public education campaign to normalise their use, something objectively ridiculous like having middle class families that actually have decent running water doing it, visibily and publicly.
A simpler approach that forgoes the lens, relies on the combination of UV and heat, and is promoted under the name "SODIS" and already in use in some places:
https://en.wikipedia.org/wiki/Solar_water_disinfection
https://en.wikipedia.org/wiki/Solar_water_disinfection
Clean drinking water is not a technical issue - as pointed out downthread, a cloth filter and boiling it on a fire will work and has done so for thousands of years.
Poverty and deprivation is tied up with a huge range if issues, from water table effects to climate change to local politics and public health and education and ... Well, if the infrastructure existed to build a million of these frames and organise water to be brought to them and then handed out to those without clean water, then any number of other technologies could easily substitute.
So not saying that supplying ten thousand of these to villages whose water tables just moved five miles won't be a fantastic use of our dollars, it's just that seems a small effect.
There is a good ted talk on tackling poverty amount at Maori I can't find it though. It walks through a lot of these issues.
Poverty and deprivation is tied up with a huge range if issues, from water table effects to climate change to local politics and public health and education and ... Well, if the infrastructure existed to build a million of these frames and organise water to be brought to them and then handed out to those without clean water, then any number of other technologies could easily substitute.
So not saying that supplying ten thousand of these to villages whose water tables just moved five miles won't be a fantastic use of our dollars, it's just that seems a small effect.
There is a good ted talk on tackling poverty amount at Maori I can't find it though. It walks through a lot of these issues.
I've seen this approach tried before - it has problems :
"Due to the sun’s movement throughout the day, Henry needs to repeatedly shift the container to match the focal point. "
"Due to the sun’s movement throughout the day, Henry needs to repeatedly shift the container to match the focal point. "
I wondered about this as well. Also an issue with NOT moving it to stay fucused on the water... a lens like that could start a grass / wood fire
Unless the project participants are willing to depend on this thing for fresh drinking water as part of their testing, the project itself is insultingly academic.
I built a rig with my son using a 65 inch Fresnel lens we harvested from an old rear projection TV. It could easily produce 2,000 degrees F under ideal conditions. Focal length was about three fee.
A 2x4 passed through the focal point would catch on fire pretty much instantly (as quickly as one could count to one).
We successfully fried an egg (more like instantly scorched an egg) by bouncing the beam pre-focal point off a high quality front surface mirror (also harvested from the TV) and focused it onto the bottom of a cast iron skillet.
Anyhow, the realization was that this thing was incredibly inconvenient and also dangerous to use. We built it into an articulated wooden frame with the explicit idea of being able to track the sun. Power output peaked and dropped off very quickly and was near useless during low-horizon times. You had to be super aware of where the focal point was at all times or risk a very serious accident. This is an obvious point but you don't fully comprehend how serious a point this is until you start setting wood on fire instantly. Even putting the thing away for the day we had to be sure to rotate it 90 degrees so that the sun hit the edge of the lens. Even then, we threw a black cloth over it just to make sure. This thing could set your house on fire in a fraction of a second.
We ended up destroying it after playing with it for a month or so. Just too dangerous to be around and pretty much useless for anything practical. After a while you get tired of demonstrating how quickly you can set a piece of wood on fire.
A long intro to say the following.
Neat trick by this student and a fantastic learning experience I am sure. Kudo's should be given. Kids learn tons of stuff doing off the wall scientific experiments like this one. In practical terms though, well, it isn't practical at all. But, who cares, this is about learning and on that point it is absolutely brilliant.
I remember seeing an article many years ago about using a folded-up t-shirt as a first-pass filter and then simple clear two liter plastic bottles left under the sun for 24 hours to make water safe to drink. People would fill these bottles with t-shirt-filtered water and either place them on a table outside or on the roof for a day. They'd rotate sets of plastic bottles for a continuous supply of safe drinking water. I couldn't think of anything simpler, cheaper or more effective.
Here's on version of that:
http://www.sodis.ch/methode/anwendung/index_EN
A 2x4 passed through the focal point would catch on fire pretty much instantly (as quickly as one could count to one).
We successfully fried an egg (more like instantly scorched an egg) by bouncing the beam pre-focal point off a high quality front surface mirror (also harvested from the TV) and focused it onto the bottom of a cast iron skillet.
Anyhow, the realization was that this thing was incredibly inconvenient and also dangerous to use. We built it into an articulated wooden frame with the explicit idea of being able to track the sun. Power output peaked and dropped off very quickly and was near useless during low-horizon times. You had to be super aware of where the focal point was at all times or risk a very serious accident. This is an obvious point but you don't fully comprehend how serious a point this is until you start setting wood on fire instantly. Even putting the thing away for the day we had to be sure to rotate it 90 degrees so that the sun hit the edge of the lens. Even then, we threw a black cloth over it just to make sure. This thing could set your house on fire in a fraction of a second.
We ended up destroying it after playing with it for a month or so. Just too dangerous to be around and pretty much useless for anything practical. After a while you get tired of demonstrating how quickly you can set a piece of wood on fire.
A long intro to say the following.
Neat trick by this student and a fantastic learning experience I am sure. Kudo's should be given. Kids learn tons of stuff doing off the wall scientific experiments like this one. In practical terms though, well, it isn't practical at all. But, who cares, this is about learning and on that point it is absolutely brilliant.
I remember seeing an article many years ago about using a folded-up t-shirt as a first-pass filter and then simple clear two liter plastic bottles left under the sun for 24 hours to make water safe to drink. People would fill these bottles with t-shirt-filtered water and either place them on a table outside or on the roof for a day. They'd rotate sets of plastic bottles for a continuous supply of safe drinking water. I couldn't think of anything simpler, cheaper or more effective.
Here's on version of that:
http://www.sodis.ch/methode/anwendung/index_EN
Another alternative is water filters. This is used in Brazil by Neymar-backed Waves For Water (90k filters) and Project AmaZon (10k filters). The latter filter design uses cheap sedimentary layers inside a framed structure. Pour the turbid water on top, and clear water comes out the bottom.
I am not entirely sure what is new here. I knowpeople that have been doing this for years. The Channel GREENPOWERSCIENCE
has done many videos on exactly this.
I'd be interested to know how it goes with different types of plastic as well.
I'd expect ETFE to perform a lot better (and last longer) than PTFE, for instance.
I'd expect ETFE to perform a lot better (and last longer) than PTFE, for instance.
I like the simplicity. We used to do the solar still thing where you put a pan of tainted water in a hole with a plastic sheet over it and a rock in the middle and the collection can under the rock. The heat evaporates the water from the pan, which condenses on the sheet and then runs down and drips off into the collection can. Not very fast of course.
Of course often times the trick is getting the water in the first place.
Of course often times the trick is getting the water in the first place.
Looks nice, but can 150 ºFahrenheit (65ºCelcius) "kill 99.9% of bacteria and pathogens" ? From https://en.wikipedia.org/wiki/Sterilization_%28microbiology%... it would seem that's not the case.
Wonder if the article considers the effects of sun ultra-violet radiation to help in that process.
Wonder if the article considers the effects of sun ultra-violet radiation to help in that process.
65C sounds like plenty enough heat over an hour.
Such temperatures are common in sous-vide (see e.g. http://www.douglasbaldwin.com/sous-vide.html - interesting headings to grep include "Pasteurized in Shell Egg" and "Computing the Destruction of Pathogens")
Such temperatures are common in sous-vide (see e.g. http://www.douglasbaldwin.com/sous-vide.html - interesting headings to grep include "Pasteurized in Shell Egg" and "Computing the Destruction of Pathogens")
Even if it could kill 99.9% of bugs now, just wait until we get the inevitable HRSA superbugs after 20 years of this.
Though this does sound neat, and it's still much better to have than nothing at all.
Though this does sound neat, and it's still much better to have than nothing at all.
This sort of thinking is often invoked to justify why the world can't get better for e.g. poor Africans, while ignoring the fact that the rest of the world has been doing it in a more effective fashion (e.g. boiling water with a fire) for literally millennia with no ill effects.
Those benighted primitives, why did it never occur to them to make a lens from 7mil clear plastic sheeting?
It's not clear to me that bacteria and other pathogens could evolve around heat sterilization. I'm sure they can adapt in some ways to some amount of temperature change, but at some point (maybe hotter than this device can achieve) surely no organism can survive.
It's like the old saying, it's easy to destroy HIV - the hard part is doing it inside a human body. In the case of sterilizing water, we don't have that problem, the water will remain usable.
It's like the old saying, it's easy to destroy HIV - the hard part is doing it inside a human body. In the case of sterilizing water, we don't have that problem, the water will remain usable.
A thermophile is an organism — a type of extremophile — that thrives at relatively high temperatures, between 45 and 122 °C (113 and 252 °F) http://en.wikipedia.org/wiki/Thermophile
So, 150 °F is not really all that hot as some organisms thrive at 250°F or well above boiling. However, I suspect organisms that thrive at 150+°F are unlikely to also thrive in the human body. A more important issue is the effort to sterilize water by hand is unlikely to be made with any real consistency.
So, 150 °F is not really all that hot as some organisms thrive at 250°F or well above boiling. However, I suspect organisms that thrive at 150+°F are unlikely to also thrive in the human body. A more important issue is the effort to sterilize water by hand is unlikely to be made with any real consistency.
> A more important issue is the effort to sterilize water by hand is unlikely to be made with any real consistency.
That's what safety margins are for.
That's what safety margins are for.
The lives saved by devices like this may end up being the ones who improve science, medicine, and technology sufficiently well enough to come up with the next innovation to improve conditions in life.
Point? Entropy is a bitch, but mankind carries a bigger stick.
Point? Entropy is a bitch, but mankind carries a bigger stick.
Guys, guys, I get it. All I'm saying is that we do actually need to try to anticipate issues ahead of time.
For everyone who's saying that nothing could evolve to resist this, please look at Legionnaire's disease: http://en.wikipedia.org/wiki/Legionnaires'_disease
This is a disease which can be fatal, and is found in association with systems involving water, including hot water heaters.
I'll grant you as much as you likely that you're unlikely to get this or that, what I'm cautioning against is the idea that you've found a silver bullet. You've never found a silver bullet against bacteria, and it's better to go into use of systems like these with that assumption.
Thinking ahead to make "thoroughly rinse, clean, and dry this system at least once a week" part of the instructions for use as a precaution against bacteria isn't nay-saying, it could be quite valuable to the people we would have using systems like these in the future.
For everyone who's saying that nothing could evolve to resist this, please look at Legionnaire's disease: http://en.wikipedia.org/wiki/Legionnaires'_disease
This is a disease which can be fatal, and is found in association with systems involving water, including hot water heaters.
I'll grant you as much as you likely that you're unlikely to get this or that, what I'm cautioning against is the idea that you've found a silver bullet. You've never found a silver bullet against bacteria, and it's better to go into use of systems like these with that assumption.
Thinking ahead to make "thoroughly rinse, clean, and dry this system at least once a week" part of the instructions for use as a precaution against bacteria isn't nay-saying, it could be quite valuable to the people we would have using systems like these in the future.
As long as good technology gets communicated well enough to be effectively applied, with real results, there is hope in the world. How we go about doing that, especially for life-destroying subjects such as these diseases, is a matter of great importance to mankind and is thus, alas, subject to all mankinds' cultures. Expressions of technological prowess mean nothing if the basics of human life, in the first place - the real rudimentary stuff, like: water, food, shelter - are nearly non-existent.
Our only hope, is all I'm saying, is in our ability to cross all boundaries and communicate under extraordinary duress, nevertheless, with effective results. So I fully support your position.
I'm encouraged by the community efforts being made to address this; there is, after all, a very large industrial powerhouse that can be directed towards these problems. If we see Ebola-bots on the horizon, better hope they're flying away and not getting closer, uh oh ..
Our only hope, is all I'm saying, is in our ability to cross all boundaries and communicate under extraordinary duress, nevertheless, with effective results. So I fully support your position.
I'm encouraged by the community efforts being made to address this; there is, after all, a very large industrial powerhouse that can be directed towards these problems. If we see Ebola-bots on the horizon, better hope they're flying away and not getting closer, uh oh ..
beautiful. use a coil as the water conduit and make it a continuous process with total heat supplied to the volume part of an inexpensive? feedback loop.
How fast does the water evaporate ? Can oil or gas be floated on top to stop it?
Could one just put water in metal cans painted black? Had no idea it only took temps of 130F to kill the pathogens that harm.
How fast does the water evaporate ? Can oil or gas be floated on top to stop it?
Could one just put water in metal cans painted black? Had no idea it only took temps of 130F to kill the pathogens that harm.
There seems to be two bits of water involved, as you probably realize. One bit, several gallons, is sitting in a saggy plastic sheet, whose bulge forms a lens. You ask a good question, could one float a skin of oil on that to keep it from evaporating?
The bit that gets purified is in a separate container held (manually?) at the focal point of the water lens, and gets hot. But as the sun moves so does the focal point, so a very patient person has to be shoving the heating container along every few minutes. This doesn't seem very practical to me.
The bit that gets purified is in a separate container held (manually?) at the focal point of the water lens, and gets hot. But as the sun moves so does the focal point, so a very patient person has to be shoving the heating container along every few minutes. This doesn't seem very practical to me.
Throw in some watertight sealing plastic bags and they could have sous vide as well. ;)
Is this better than boiling water over a fire?
Fire requires fuel. Fuel is scarce in much of the world.
That was my thought. A small fire can heat a litre of water to boiling in a lot less than an hour. And you don't need to actually boil water to sterilize it, 160-180 degress F is adequate.
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Indoor cooking fires are a significant source of pollution in developing countries. A solar-powered solution would be a significant improvement.
Suffering in abject poverty is infinitely worse than pollution. It doens't even compare. Thus, developing countries should optimize for economic efficiency. Hurting human well-being in favor of environmental "well-being" is criminal.
Particulate pollution kills people and causes suffering, mostly to women and children.
http://www.who.int/mediacentre/factsheets/fs292/en/
http://www.who.int/mediacentre/factsheets/fs292/en/
Over 4 million people die prematurely from illness attributable to the household
air pollution from cooking with solid fuels.
More than 50% of premature deaths among children under 5 are due to pneumonia
caused by particulate matter (soot) inhaled from household air pollution.I'd rather die prematurely from pollution, than die immediately from exposure or lack of clean drinking water.
Pollution really is way, way down on the list of concerns for people in impoverished nations. Water, Shelter, Food are much more pressing concerns.
Pollution really is way, way down on the list of concerns for people in impoverished nations. Water, Shelter, Food are much more pressing concerns.
You misunderstand. Indoor cooking fires are a major source of indoor air pollution that sickens the families, and particularly the women. Not to mention, many women spend hours per day gathering and hauling wood for their fires.
Wood or other biomass-fueled fires are CO2-neutral, but do cause particulate pollution. There have been a number of efforts to develop clean-burning wood stoves for developing countries to combat that problem.
"Wood or other biomass-fueled fires are CO2-neutral"
Okay, I'll bite. How does burning wood not result in a net increase in CO2? Are you assuming that for every cord of wood burnt, that someone is simultaneously planing and growing a cord's worth of tree (which, of course, pulls carbon out of the air?)
That's a pretty big assumption.
Okay, I'll bite. How does burning wood not result in a net increase in CO2? Are you assuming that for every cord of wood burnt, that someone is simultaneously planing and growing a cord's worth of tree (which, of course, pulls carbon out of the air?)
That's a pretty big assumption.
Carbon embodied in wood is current-cycle carbon, it's already part of the biosphere. In most cases, it was sequestered from the atmosphere at most a few decades ago, for the very oldest trees, a few centuries (and most of those aren't burned for fuel).
Carbon embodied in coal, oil, and gas was last part of the biosphere hundreds of millions of years ago. And that's precisely the problem: humans have re-introduced, mostly in the past 50 years (95% of all oil was burned since then, a large portion of coal and gas) carbon that was deposited over hundreds of millions of years. The biosphere portion of the carbon cycle (atmospheric uptake, oceans, plant growth) simply cannot keep up.
Yes, if you were to burn all forests at once, you'd run up CO2 a bit. That is, however, a pretty self-limiting prospect.
Carbon embodied in coal, oil, and gas was last part of the biosphere hundreds of millions of years ago. And that's precisely the problem: humans have re-introduced, mostly in the past 50 years (95% of all oil was burned since then, a large portion of coal and gas) carbon that was deposited over hundreds of millions of years. The biosphere portion of the carbon cycle (atmospheric uptake, oceans, plant growth) simply cannot keep up.
Yes, if you were to burn all forests at once, you'd run up CO2 a bit. That is, however, a pretty self-limiting prospect.
In fact, I took his statement the other way:
At one point, there was some n amount of CO2 in the air.
A tree was planted. Through a few biological cycles, CO2 is exchanged and stored as various sugars within the wood.
Burning the wood releases the CO2 back into the air.
This is a net zero process.
At one point, there was some n amount of CO2 in the air.
A tree was planted. Through a few biological cycles, CO2 is exchanged and stored as various sugars within the wood.
Burning the wood releases the CO2 back into the air.
This is a net zero process.
On a large enough time scale burning coal is net zero, too. (It's just, that we don't care about these scales.)
The impacts of release (or sequestration) on those scales on other ecological systems are non-trivial. Which is why we care about those releases.
I happen to agree with you; just pointing out what I thought OP meant.
If you don't burn the wood, it will naturally decompose and release the same amount of C02 into the atmosphere. Possibly with methane which is an even worse greenhouse gas.
in areas where fuel is pricey or ecologically unsuitable, sure
Water with a lot of pathogens is likely to have high turbidity as well so your lens is going to be a bit opaque.
That focal point must move in a predictable way, I wonder if a shaped vessel could be under it for long enough.
That is, unless it's not really a technical problem.
Articles such as this don't often delve into broader issues of public health, education, or even poverty, but with an issue as complex as water access, perhaps we out to discuss it in a more complex context.