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Gray-B-Gon wind-powered evapotron for graywater disposal

Gray-B-Gon wind-powered evapotron for graywater disposal
Here is a wind-powered graywater evaporation device for your Burning Man camp.  It will eliminate, legally and responsibly, all the wastewater produced in a medium-size camp, or several small camps.  (Except for what belongs in a porta-potty.)

Burners dispose of their graywater in many ways, from "pack it out" to black-plastic-lined evaporation ponds to fullblown water-purification systems designed by professionals (who make coffee using their secondhand water!)

This device, the Gray-B-Gon evapotron, is the result of many years of using and improving.  With typical winds, it evaporates or disperses fifteen to twenty gallons of water a day.  (Maximum measured: 2 gallons per hour in high wind.  Don't try this at home.)  The rotating drum design avoids two performance killers of passive evapotrons: loss of wick absorbency, and reduced performance due to accumulated playa dust. Dust just washes off the Gray-B-Gon's drum, in a single rotation.

It's useful, and it's attractive!  The flashing propeller blades and the slow-moving drum catch people's attention.  The (almost always) excess capacity lets you offer graywater disposal to nearby camps, forming a neighborhood center the way village wells have done for millennia, only backward.

There are five subassemblies: the tray, two masts, the drum, and the propeller.  During construction, you will assemble a complete evapotron (except for the black plastic tray liner and the panty-hose filter.)  Once you've tested it in some wind, and it works, you can dismantle it (dismount the propeller and masts, and collapse the drum) for transporting to the playa.  There, setting it up and putting it into operation takes under an hour.

As you prepare to leave the playa you dismantle it again, then lift the muddy plastic liner from the tray and dump it into your trash bag.  With a water-spray cleaning, another old towel and a new plastic liner, your evapotron should be ready to go next year.

A word of caution

While you're enjoying watching and using your evapotron, keep in mind that graywater is unsanitary and can be hazardous to your health.  Step 32 describes periodic disinfection with chlorine bleach.   The subassemblies you take home are unsanitary too; but so is a handshake, or sharing eating utensils.  If thinking about this makes you want to wash your hands, do it.

Time and Money

On your own, construction takes about a day or three.  It uses common tools that are probably in your garage or shop, plus two or three you might want to buy.  Materials cost varies, depending on what you have on hand, up to about $200.

Alternatively, join a one-day construction workshop, where we provide most of the parts at cost (around $65 including wheels) and the wood parts are precut.  The construction time is one full day, less if you have friends helping.  You provide the CD, the bucket, the used panty-hose,  and, optionally, castoff bicycle wheels scrounged from basements, garages, recycling centers and bike repair shops. 

Further Information

Please visit evapotrons.info , which contains discussions, workshop dates, and other useful information.         4/26/12
 
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Step 1Varnish -- the secret of long life

Varnish -- the secret of long life
A coat of varnish on wood parts will greatly extend their lifetimes. The desert is tough on wood, especially end grain and plywood edges. Your evapotron will last years longer if, before it's assembled, every wood part is sealed inside a plastic skin.

The finish I use is a water-based exterior polyurethane with a matte or satin  finish (non-glossy). Water-based Varathane is one such product; it costs about $17 for a quart can (enough to cover three evapotrons). It's easy to apply, and doesn't require a skilled hand. You can coat all sides of a piece at one go, resting the piece on points or edges (just not a face) to dry. It dries rapidly to the touch; if you do your varnishing just before lunch, when you return the surfaces will be dry and workable. Water-based polyurethane has very little odor, and brush cleaning is easy. Do rinse out the brush thoroughly, several times, in clear or soapy water. Or,if you're going to do more varnishing the same day, you can put an unrinsed brush in a plastic bag, squeeze out the air, and refrigerate it.

Newly coated pieces will feel even rougher than before; that's because the surface fibers of the wood are now stiffer. A few strokes with sandpaper or a sanding block will smooth them down nicely.
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28 comments
Feb 18, 2012. 10:06 AMgerflash says:
Thanks, Larry! I will try all your suggestions.
Feb 17, 2012. 6:56 PMgerflash says:
I built this thing three years ago, and it's been mixed blessing on the Playa. Our main challenge is that the axle nuts tend to "wind up" and lock down on the axle, preventing the drum from turning - definitely a bummer! Looking for a solution to this challenge. Any suggestions?
Jun 7, 2010. 9:07 AMJayMarlette says:
Thank you for displaying your evapotron at the Noobie Picnic. I am very excited about building this. jay jay@houseman.org www.houseman.org
Feb 16, 2010. 11:54 AMbuteman says:
Would it be easier to melt through the plastic with a piece of 1-3/8" pipe to make the hole?
Mar 20, 2010. 11:47 PMbmnot says:
The instructables membership pay-wall prevents me from accessing the full plans, despite the creative commons license of the plans / project specifying non-commercial use.

So which is it?
Feb 16, 2010. 9:41 AMbuteman says:
"Watch out for my favorite error: drilling a body hole through both top and bottom pieces of wood, rather than just the top piece. The bottom piece gets only a pilot hole."

mine too. What I try do do now is clamp the  pieces I want to join, drill the pilot hole through both, separate them and then drill the body hole on just the one.
 
   
May 17, 2009. 3:12 PMrimar2000 says:
This is a great job, I like it, but I don't totally understand the principle of gray water evaporation. Can you add an explanation about that?
Oct 9, 2009. 6:45 AMchrisnotap says:
What a great project!  Photo's and descriptions are great. You probably had a lot of fun doing this. I noticed above in the 3rd part you say "A propeller pointed in the right direction will always catch the wind," I have been researching wind devices for a small wind powered water pump I am working on to build. One that comes to mind to possibly improve your design is a savonius wind turbine.
http://www.reuk.co.uk/Savonius-Wind-Turbines.htm
It does not matter which direction the wind comes from,it will always catch it, they are high torque and have a maximum built in speed.  Keep up the good work!
Oct 9, 2009. 9:46 AMrimar2000 says:
Chrisnotap, the VAWTs (Vertical Axis Wind Turbines) has only a 50% máx of efficience, because they can't use all profile. (pardon my Google Translator English)
Jul 13, 2009. 11:06 AMrimar2000 says:
Thanks very much, Larry.
May 13, 2009. 3:40 AMextrordinary1 says:
Very nice job making your blades. Do you have a template I can get for this pattern? I see the holes you made for securing the vanes to the wheel, obviously with the zip ties you mention. I may wish to use a 26 inch wheel and secure 4 cogs to catch another set on another shaft, to crank a small low powered 12 volt generator to trickle charge my scooter battery when needed.
Sep 19, 2009. 6:24 AMextrordinary1 says:
Thanks for the recent update. My version of this as a wind generator is simply to drive a small dynomotor just like the small generators used for lights on bicycles, but at least cranking out one amp, at 12 volts. This would easily do that. This would allow me to trickle charge my battery while not driving the scooter, as it goes dead easily if I don't drive it everyday. Here in Missouri, it is not uncommon for straight line winds from storms to come through at 60 to 100 mph. Your typical wind generators can't continue to crank power in that stong of a wind. A friend of mine has a very large wind generator with a 3 ft. dia. concrete tower. With his brake set knowing a very storng storm was coming in, the wind snapped his tower. Based on past experience, my 68 inch wind generator using 12 blades made of six strips of fabric, ripstop nylon, survived that very same storm that destroyed his 40,000 dollar wind generator. I'm not cranking out 10 kW like he was, but it works in lower wind speeds his doesn't, and could handle higher winds easier. After he rebuilt it, he had his brake set just before another storm came in. He heard a loud shot, went outside to see what was going on, and he saw a power company truck driving off down the highway, alone. We have net metering here in MO, good luck collecting what you put back into the grid.
The meters clearly mark, plus or minus 20% accuracy... he eventually noticed that shot, took a large chunk out of one of his 3 blades. His brake has been set ever since.

I like the idea and how you presented this potential, as I may use it myself if I return to a rural lifesyle. Nice job you have done here.
May 14, 2009. 10:22 PMextrordinary1 says:
Thanks for the reply. I especially liked the pattern you used, but I plan to make it from stainless steel up to a 6 ft. dia. I'll have to design a strong hub for it, and I plan to build my own brushless AC generator. I mostly liked the appearance of your blades and wanted to scale them up for my project.

I'm working on one now that has 12 blades of flashing secured to a hub and an outer ring that is 3 ft. dia. The last one I built stood up to 70 mph winds, but when the micro burst hit us at 100 mph wind, the blade assembly came off and I found it two blocks away, undamaged. Needless to say I secured it stronger after that. I liked another guys 3 bladed design, but he used pvc and I don't believe it will take the stresses of storms we get here in Missouri. I can see that small section with only two bolts snapping under stress. I would be hard pressed to be able to bend stronger metal brackets in a shape that would strengthen them along the vertical axis of the blade assembly.
Sep 10, 2009. 9:54 AMreptilevet13 says:
Hi Larry! I heard you on the BMR last week talking about the Gray-B-Gon and I am hoping to build one of these fantastic contraptions for next year! Thanks for getting the word out there about your design! Where are your construction workshops held?
Jun 6, 2009. 9:35 AMEvaporator says:
What is tulle mesh?
Apr 18, 2009. 11:03 AMA good name says:
I don't get it, what's the wind power do?
Apr 2, 2009. 7:26 PMstrad27 says:
Since the propeller apparatus is fixed in place, when the winds shift, what is the effect? Do you rotate the entire unit, or did you find that unnecessary? We're very interested in adding this type of wind-driven movement to our existing pond to speed the process up from last year. Also, in light of 2008 dust storms, did you find any problems with sediment build-up? Last year we had plexi walls which helped, but we would lose those if we followed your plan.

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Author:Larry Breed