I made it from an old rectangular plastic kitchen garbage container. On the 2 large sides I cut a hole app. 12″ square, and covered the hole with replacement pads from an evaporative cooler. A small fountain pump and some clear tubing runs water over these pads. The top of the garbage can is covered with a piece of plywood with a hole cut in the center, and over this hole is mounted a 12V fan (either large computer muffin fan, or a salvaged ventilation fan from an old car). This fan is set up so it pulls (exhausts) air from the trash container, pulling it over the wet pads. A piece of dryer vent hose directs this air into the vehicle, tent, or whatever space you want to cool. The whole thing is powered by a solar panel. The fountain pump draws less than an amp, so size your fan based on the amount of solar power you have available.

The key to making this work is to pre-treat your greywater. I collected the shower water in a blow-up kiddie pool, and then transferred it to a 5 gallon bucket. I treated the water in the bucket with Alum (a flocculant) and bleach. The alum causes the suspended particles of playa dust to clump together and settle to the bottom, and the bleach sterilizes the water. After a little experimentation, I found that a teaspoon of alum and about 15 drops of bleach per 5 gallons worked well when allowed to sit overnight. After the water has settled, it can be transferred to the swamp cooler. Be careful not to stir up the water while transferring it, and you can get almost all the clear water leaving only a couple of inches of muddy water in the bottom of the bucket.

Alum can be bought in small containers at the grocery store (look in spices, it’s used for pickling) or in larger containers at swimming pool supply stores.

I probably won’t be at BM 2007, but would be happy to loan my prototype to someone, or to answer questions.

Steve steve_susswein@hotmail.com

On the playa, “graywater” or “grey water” are terms for water with contaminants that make it unsatisfactory as drinking water, but that wouldn’t normally require a septic waste system for disposal. Graywater includes ice-melt in coolers, shower water with soaps and cosmetics, kitchen waste including dishwater and scraps from food preparation (including raw meat), and toothpaste and saliva. Also a good bit of playa dust.

“Evapotron” is a highfaluting term, coined for Burning Man, for graywater evaporating devices suitable for use and operation by members of a camp. The term “evap-o-wheel” has also been used for an evapotron using rotating evaporative surfaces.

Three of my designs relied on wind power, and for them the corral was great for public attention but not for evaporative performance, because the wind and sun were often blocked by nearby structures. Non-wind-powered devices were no doubt affected as well. To get reliable estimates of performance we need to evaluate all the evapotrons in a more typical camp environment with fuller wind and sun exposure.

Each of the devices stood over a “pond” of on-edge 2×4s surrounding a plywood floor, about 24×48 inches, covered with black plastic sheet. I built the ponds and fans (salvage bike wheels with aluminum-sheet blades attached to the spokes) at home. The devices were brought to the playa as almost-flat components, then assembled.

“The Clothesline”

This design focuses on ease of construction. It is nothing more than an evaporation pond, and fabric that hangs above the pond and dips into the water. One end of the clothesline is easily detached from its support, to permit dunking the fabric fully into the water, then lifting it again to dry.

The clothesline would be a good solution for a small camp. Building it requires little construction skill or time, and in use it needs attention for a few seconds a few times a day, to dunk the fabric. The pond walls need to be taller than 3-1/2 inches; my device’s pond was too shallow to fully dunk the fabric.

“The Nonokini”

The Nonokini is a single bike-wheel fan with fabric wrapped around its nine blades. As wind rotates the fan, the fabric on each blade in turn is wetted in the pond, then lifted to evaporate or to disperse droplets downwind. The intent was to exploit the useful properties of bike wheels, without needing much mechanical tinkering.

Although the low wind made judging performance difficult, I think the Nonokini design would not perform well. The evaporative surface is relatively small, and the side of the fabric that touches the blade can’t evaporate at all. The water released as droplets may land on the ground or may annoy people downwind.

“Archie”

The Archie evapotron uses a bike-wheel fan to drive a bidirectional pair of Archimedes’ screws made of vinyl tubing wrapped around an inclined length of plastic pipe. Water lifted to the top of the screw is dispersed onto several sheets of fabric, to evaporate.

Archie was the most intriguing device to watch, but had several problems. The fan is close to ground level and therefore in very low wind; it is also tilted and shielded from the wind in one direction by the evaporative fabric. These problems could be overcome by making the screw longer; the fan could be elevated to 6 or 8 feet, where it would be in full wind, with a screw 12 to 15 feet long.

Another problem was that after a few days, the fabric became coated with playa dust and graywater contaminants. It lost virtually all its absorbency, and water released at the top ran straight downward without spreading within the fabric by capillary action. Evaporation diminished to near zero. I think the reason that only Archie was affected this way is that the other devices all had fabric moving in the water; contaminants could dislodge, to settle at the bottom of the pond.

I speculate that the evapotrons in several camps that trickle water over hardware cloth, rather than fabric, are successful because the metal mesh is so coarse that contaminants can’t form a continuous coating, as they do over close-mesh fabric. Perhaps a tall Archie using hardware cloth would perform well.

“Old Number One (rev. 2.2)”

Old Number One will in time get a more descriptive name. It’s a redesign of the evapotron I built in 2005. A fan carrying a clothesline pulley is mounted above a fabric-covered drum that is partially immersed in a pond. A drive belt from the fan causes the drum to rotate, dipping into the pond and carrying wet fabric up into the air and sunlight for evaporation.

To save travel space, I assembled the drum onsite. The drum ends were bicycle wheels, held apart by an 18-inch-long plastic pipe with ends notched where spokes touched. #12-24 allthread through the wheels’ hollow axles clamped the assembly together. String laced zigzag from rim to rim supported the fabric and also strengthened the assembly. In attaching the fabric, the ends were left free, which produced flaps that scavenged water from the bottom of the pond.

I made the drive belt from lengths of stockings or pantyhose legs. A very tidy knot for connecting them exploits the “hose” of the hosiery: tie an overhand knot in the end of one length; slide it into the end of another length; tie cord around the end of that length, to capture the overhand knot within. The drive belt is, naturally, very stretchy. Wet it, then stretch it substantially as you decide on the length you need.

Because a bicycle wheel rim looks like a pulley, I tried to use it as one for the drive belt. The belt repeatedly fell off the rim, requiring me to tinker with wheel alignment and belt tension. In hindsight, I realized the drive belt could have traveled on any part of the fabric drum; it didn’t need to ride on the rim.

This evapotron design was the most effective of the four. In sufficient wind, my 2005 device evaporated (or dispersed as droplets) as much as two gallons per hour. “Rev. 2.2” raises the fan from ground level to about 40 inches, where it catches more wind. The drum fabric is old sheets; I think it’s an open question whether using a more-absorbent or faster-drying fabric would make a significant difference.

Additional notes

Evapotron designs must consider disassembly and disposal as well as operation. Unevaporated water must be disposed of; this means getting it out of the pond, straining it (if that wasn’t done already), and scattering it or packing it out.

Once they were dry, I removed the fabric strips and black plastic and packed them out in my trash; apart from that, the devices were relatively clean and could be disassembled and packed out. I burned the wood of most ponds rather than taking them home to store.

Treating (disinfecting) graywater is important for camp safety, but reliable guidelines have not yet been established. Clorox is readily available but may not be the best approach. Its effectiveness is significantly reduced in water carrying suspended solids, so a concentration appropriate for purifying drinking water may be insufficient. Whenever more graywater is added, more disinfectant must also be applied.

Lining an Evapotron Tray

To hold their water, many evapotrons use a shallow tray with a floor of plywood and a rim of 2×4’s standing on edge. To make it waterproof, it’s lined with a sheet of black plastic. I wrote this to remind myself how to do the lining.

To begin with: the one important function of the plastic is to hold water. It doesn’t need to be tidy and unwrinkled, but it does need to be free of holes. Use new plastic sheet fresh off the roll, or check re-used plastic very carefully. What thickness? Thicker than a typical plastic bag, so it’s not fragile. It doesn’t need to be strong enough to support the water’s weight. The wood does that.

You will also need scissors and a stapler, the kind that can push staples into wood.

Determine the length and width you need, and cut the plastic sheet a couple of inches longer and wider. The length is the length of the plywood floor (outside measure), plus twice the height of the rim (twice 3-1/2 in. for a 2×4 rim.) Thus a floor 48 in. long requires a sheet length of 48+7 = 55 in., so cut 57 in. Similar math determines the width.

Now you will staple the plastic to the top of the rim only, but don’t start by stapling! Almost any mistake you make in positioning the plastic means a hole in the wall or floor, and you get to start over with a new sheet. Instead,

Place the plastic in the tray with a weight holding it down at each corner. Adjust the position so the plastic covers the rim tops and is fairly flat across the floor. Don’t worry yet about the plastic bunching up in the corners. Staple the sheet to the rim tops starting 3 in. from the corners, with whatever staple spacing you like.

To get tidy-looking, waterproof corners, grasp a corner of the plastic and pull upward and slightly inward. The plastic will form a fold in a straight line from your fingers down to the corner of the floor and rim. Now pull the plastic outward over the outside of the rim corner. With a little tucking, the formerly bunched-up plastic will form a neat squared shape on top of the rim corner. Staple it twice, once on each side of the diagonal. Repeat on the other three corners.

Trim the excess plastic along the rim’s outer edge, and you’re done.

In 2009 I had just published (on Instructables.com) a construction guide for building Gray-B-Gon evapotrons.  Since then, I’ve held five construction workshops in the SF area, and last year evapotrons on the playa consumed 500-1000 gallons of wastewater PER DAY.  I have built a website for evapotrons:  the easy-to-remember URL is  evapotrons.info, which forwards to the real URL,  https://sites.google.com/site/evapotrons/home .  You’ll find pix and words about every practical or intriguing evapotron design I’ve come across; also a dauntingly detailed guide to putting on a workshop in your own locale.  (Don’t be daunted!  It’s not that hard, really; and I’ll help.)

The Gray-B-Gon itself has many minor improvements (colllapsible drum; wheel balancing; belt traction; Clorox info; easier knots etc.)  which are recorded in the Instructables guide and in the same document, freely downloadable, on the website.  This year I will be testing a redesign that I expect to give a 2x performance improvement.  Residential evapotrons don’t need this — they usually run dry already — but I have my eye on the lucrative industrial market:  big camps using giant, inefficient evaporation ponds.  HeeBeeJeeBees tried a GBG last year, saw the effect, and asked for another.  The high-performance model, code name Jumbo, has the same footprint as always.  It just drops into an evap pond and goes to work with three times the evaporative surface area.

This is a HUGE photo of the inside of the BRCMUD dome: you can see all the plants they watered with the reclaimed grey water. They also sprinkled water on the dome’s burlap cover for cooling.
http://www.anybodyburns.com/2003/wallpaper/domelife.jpg

photo is worth 1,000 words.

Water your would not like to drink. (shower water, dishwater, toothbrushing water)
(Black water is what goes down a toilet)

How can I minimize the creation grey water?

• Take less water to the playa: you will conserve water if you bring less! However 1.5 gallons per person per day is the bare minimum. You don’t want to have to ration your drinking water in the desert.
• When you shower, get wet, turn the water off, soap up (scrub those nooks and crannies), then turn the water back on to rinse off
• Shower with a friend: a friend can efficiently rinse the soap off as well as wash your back
• Use a pump-up pressurized water sprayer for dish washing http://www.nextag.com/pump-sprayer/search-html
• Minimize the creation of dirty dishes: eat right out of the pan! Share utensils!
• Lick your dishes clean! Then swirl with clean water to remove any food bits –> next, drink that water! YUM!
• Wipe out dirty dishes with paper towels/wet wipes or use paper dishes: burn the paper in one of the burn barrels

What are the rules about disposal of grey water on the playa?

[This is a recollection, and needs verification]

BLM’s list of stipulations for Burning Man forbids disposing of untreated graywater on the playa. What constitutes treatment is not specified, but would probably be satisfied by filtering out solid matter and disinfecting with Clorox. An amount of water sufficient to create a muddy patch is of concern; smaller amounts aren’t. Playa visitors not attending Burning Man aren’t bound by stipulations, and should be guided by common-sense wilderness ethics.

GREY WATER DISPOSAL

-copied from:

Most camps need to dispose of grey water during Burning Man. Grey water is produced from cooking, dish washing, and hair and body washing. Our permit from BLM does NOT allow us to dump grey water directly on the playa. Therefore all grey water must be collected. Camps can then remove that water directly off the playa (by themselves or using Johnny on the Spot). Some camps may choose to use evaporation ponds to reduce the amount of water they need to haul off the playa, but these ponds can easily get clogged with dust. Some camps have even developed technologies to reuse their water. The appropriate methodology for you depends on the size of your camp, your background and experience, and the level of energy you want to spend dealing with grey water.

What’s Simple? Small and mid-sized camps can collect your grey water and take your water to several RV dump stations along highway 80 and in Reno after the event. See below. Please check with the dumping station before the event for disposal charges and determine if they can handle the amount of water you are planning to dump! Larger camps should consider setting up a contract with Johnny on the Spot to collect grey water. With 30 days notice, they will provide a collection tank for you at the event that they will collect at the end of the event for disposal.

How can I reduce my grey water? First — remember Conservation, Conservation, Conservation! In your kitchen area, set up a low-volume water spray over a basin, for dishwashing and hand cleaning. You need remarkably little water to wash up with. Assign a water cop in your camp to remind campmates that you’re in the desert, not at home. Use a biodegradable detergent instead of soap. Camp Suds, works well for dishes, hands, and showers. Rub your hands with a few drops of a waterless disinfectant lotion, available at drugstores, before you handle food. This saves water and is also good camp hygiene. Evaporation ponds are a technique that has been shown to reduce the volume of grey water. Though it’s important to construct a pond that is big enough for your camp. Too big — it will still work great. Too small — it stops working when the water gets too deep! Also limit showers the last few days of the event before you’ll need to pack up the evaporative pond for disposal.

What about scattering my grey water? For reasons of sanitation, and sheer volume, both Black Rock City and the BLM discourage scattering. However, if you’re in a very small camp, with minimal dish and body-washing water, you might choose to pour your grey water through a filter or sieve (eg a paint sieve or pantyhose), disinfect the water, then, since it is treated, disperse it on your street to keep down dust. A watering can works nicely for sprinkling.

What are the reuse options? While some camps supported by environmental engineering students have developed elaborate systems to treat the grey water for reuse, most camps do not have the expertise to treat grey water to be clean enough for misting and drinking.

How do I build an evaporative pond? The following design is borrowed from Astral Headwash, who has won the valuable ‘Earth Guardian Camp of the Day’ award for several years. This pond will dispose of up to 15 gallons a day, and is easily expandable.

Materials and Construction for a 15 gallon evaporation pond

You will need:

• four 2×4′s 8 feet long,

• black plastic sheet, 6 mil thickness, 10 ft by 10 ft,

• 3″ screws

• a screw gun (cordless drill), or

• nails and a hammer,

• a staple gun,

• a pump and a grey water container

• and gloves.

• Contact: Bob Meydenbauer of Astral Headwash meydenbauer(at)yahoo(dot)com
Contact: Larry Breed, Earth Guardian, ember(at)burningman(dot)com or earthguardians(at)burningman(dot)com

• Simple Shower Design from NoseFish

• BRC MUD Grey Water Treatment Web site: http://www.freshmakkur.org