Playa Tested Greywater Evaporator

[Toolmaker]

any thoughts about using a heat conductor like cooper to speed up evap. process

....apparently you are thinking along those lines, do tell!
I did proposed a Fresnel lens evaporation greywater system (and aluminum can smelter) a few years back...

Did you get anywhere with the lens assist evap? The thought popped into my head awhile back but I had figured if it would work someone at Earth Guardians would have tried it already. I don't have access to lenses but was thinking of trying a "greenhouse" kind of enclosure. This would keep spray contained and possibly keep odors down some as well. The increased temp may or may not speed up evaporation.

[MikeVDS]

From wikipedia:
http://en.wikipedia.org/wiki/Evaporation

Factors influencing the rate of evaporation

* Concentration of the substance evaporating in the air: If the air already has a high concentration of the substance evaporating, then the given substance will evaporate more slowly.
* Concentration of other substances in the air: If the air is already saturated with other substances, it can have a lower capacity for the substance evaporating.
* Flow rate of air: This is in part related to the concentration points above. If fresh air is moving over the substance all the time, then the concentration of the substance in the air is less likely to go up with time, thus encouraging faster evaporation.
* Concentration of other substances in the liquid: If the liquid contains other substances (such as salts), it will have a lower capacity for evaporation. This is due to Raoult's law.
* Temperature of the substance: If the substance is hotter, then evaporation will be faster.
* Inter-molecular forces: The stronger the forces keeping the molecules together in the liquid state the more energy that must be input in order to evaporate them.
* Surface Area: A substance which has a larger surface area will evaporate faster due to the fact that there are more surface molecules which are able to escape.

There is more information, charts and formula for evap rate there too.

Good ideas but I'm not sure the copper or greenhouse will help. The greenhouse will keep relative humidity high which prevents evaporation(which I think is the point of a greenhouse?).

The copper in the water probably will not help much. You have a certain area of sunlight and absorb a certain amount of that light (which is why many people use black tarps). Unless the copper helps absorb more of the light, it's not increasing the energy of the system. If the copper is outside of the water area, then you are increasing the area of light you're absorbing, but then you have to ask why are you increasing the area with copper instead of with the water, which would probably give a better return in the first place. Also it could hurt you, acting as a heat sink for your water system. As you've probably noticed before, water in a dark container can get very hot in the sun. Adding surface area to the wind could actually leave your copper cooler than your water system and cool it. It could be done, but you'd probably have better results by just adding another bucket holding water.

The lens has the same problem with surface area. It's only taking in energy from it's cross sectional area facing the sun. If that interferes with light that would normally hit the water, there will be no net gain. The way you could get this to work, is that you can take a small amount and make it hot locally. The hotter you get the water the faster the increase in evaporation rate. So if your system is small relative to the lens, you could get an increase worth your while. Coupled with a float and fill system you might have a really efficient system.

[Dork]

Ok... lessons learned last year:
1) Kiddie pools and hardware cloth are a pain to transport in a small car, especially when coated with gray water residue
2) Pumps need at least a half inch of water before they operate, which means any design with a flat, level bottom will not be able to evaporate all water or pump itself out at the end of the week
3) The flow of water up and over the edges is erratic in the wind

I picked up some cloth - sort of like the stuff used in those mesh laundry hampers. It will be a lot easier to transport and can be positioned any way I want - I'm not limited to a rigid cylinder shape. I figure a tapered shape will have less spatter. It might even wick water up a bit when the pump isn't on, but I haven't verified this yet. Downside is it won't allow as much airflow, and it won't support the top. I still need to figure out how to hold the top up and allow for angle adjustment.

The base will be wood - sort of a shallow, inverted pyramid with the pump at the bottom.

The pump is smaller than the one last year, which should hopefully result in less splashing. The new fabric won't require as much flow - just enough to keep it wet.

Anyone else modifying their design?

[motskyroonmatick]

I just bought another kiddie pool to use as a shower basin. It will drain to a 5 or more gallon sump and then a float controlled pump will deliver the water to the evaporator. Using a sump last year made it so I only had to take home a very small ammount of grey water.

[kevinwells]

I built a modified, smaller, verssion of this last year and it handled all the water from coco velvet and the adjacent camp...

I used a 2x3 cement mixing tray, a sump pump, hardware cloth, a deep cell battery which we never needed to recharge and misc bits... easy to build and it really works great. Highly reccomend this design. simple and it works...

[Tom.Jennings]

Very cool, as all have said!

Do you use it only on shower water and other relatively clean sources? Our camp is fairly frugal, and our main source of greywater is dishwashing, which is really loaded with fats and soaps. We've been bulk-filtering it, settling it, and for the cleaner stuff, sprinkle-can on the road. The nastier stuff (and filters of course) haul home.

Any clever suggestions on getting the fats, soaps and colloidal gunk out so that the water can get recycled or evaporated?

[Tom.Jennings]

Hey, rather than clog up this evap thread with garbage (har har har...) I started a new one for pre-filtering issues.

viewtopic.php?t=20290

[Phaedrus]

Greetings beautiful people. I'm glad to have found this thread.

I'm new to the BB, second year @ BRC. Last year we had a wicked huge evap pool for 40-50 ppl and it worked fine. But this year we're at more like 135 people so I'm trying to get more capacity from less space and this pump/hardware cloth design seems just the ticket.

The 3 primary advantages this design brings are:
1) Increased surface area. The cylinder has ~48sqft of vertical surface area + ~12sqft of horizontal surface are. More area = more evaporating, especially when combined with...
2) Constantly moving water. Moving --> evaporating.
3) Small footprint conserves space in camp.

But the engineer in me has some concerns about the inherent disadvantages (always trade offs!). I was hoping to hear how those who successfully used this design have managed them. In no particular order:

SUMP (for those who don't know, these pumps need ~1" of standing water to work): Easily addressed by ditching the kiddie pool (goodbye transport hassle) and digging a small sump area in the center of a "conventional" evap pool prior to laying the plastic sheeting. (I know digging in playa is frowned upon, but a hole 1 foot square by 4 inches deep is superficial and less damaged area than 6 rebar stakes)

LEVEL: No matter how hard you try during building, it will not come out absolutely level. More water will inevitably run to one side than the other. Any ideas on adjusting that after it's built? Matchbooks for shims?

ANCHORING: What keeps this tower upright and prevents it from blowing over? I see no signs of guys or any attachment in the picture. Is it freestanding? (yikes!)

POWER: 12 VDC is definitely the way to go. Boat bilge pumps are probably the best bet. After committing to the extra cost & complexity of a pump, getting juice out of a car isn't too hard.

OTHER: Switches for automation are cool, but they clog, jam, break and cost $.

Really, my main questions are Levelling and Anchoring. Any thoughts?

Thanks for any help.

DC Chris

p.s. My alternative design to this is non electric and maximizes the surface area aspect (but does admittedly still take up more space). It basically involves using multiple clothes lines with draped T-shirts that are lowered into the rectangular conventional evap pool and then pulled tight to dry (lowered by hand a few times through out the day).

A 12'x20' pool could have ~8 strings of ~10 shirts for ~80 shirts total. Since each shirt is about 2 sqft/side, 80 shirts is ~320sqft. This is more than 5 times the surface area as the pump/hardware cloth design. The down side is that it requires a small amount of human intervention to drop/raise the lines periodically.

Obviously this isn't as nifty & compact as a 10'x10' area for the pump/hardware cloth design, but it seems to me it would be more reliable & (possibly) cheaper (I think I have at least 20 old T-shirts myself).

Has anyone tried the clothes line/ hanging fabric solution to increasing evap area efficiency? The main issue I see is wind load on the lines themselves and whatever they're anchored to. I would address that by letting the lines go slack and hang in the evap pool below during high winds. Are there other problems with my idea? I'm just trying to Keep It Simple, Smartypants.

Just some thoughts & ideas. Feedback most welcomed.

[Dork]

I guyed mine down by hooking candy cane rebar over the top of the pool, then zip typing the hardware cloth to the rebar. It was probably unnecessary - the only thing the wind could potentially catch is the top, and it's pretty stable. If I were using hardware cloth again I probably wouldn't bother guying it down at all.

I tried to fix the 1" requirement by gluing down a scrap piece of 3/4" plywood to the bottom of the pool. It helped a little, but was heavy and had gaps where the water would sit. I built the whole thing out of OSB this year with an indentation where the pump sits.

I kept it level by stuffing plastic bags, fabric, whatever I had under the hardware cloth. This worked ok, the only downside being that I had to keep sticking my hands into the muck to get it right.

I didn't automate it at all - just hook the aligator clip to the battery to turn it on.

[KernelSander]

We used a bilge pump last year to very good effect - no more shower restrictions due to evap issues! We used a very small pump and constructed an A-frame from 1/2" EMT; a 4" diameter piece of ABS pipe along the top of the A-Frame with end caps distributed the water through holes drilled in the bottom on each side. The A-frame was covered in greenhouse cloth. The pump was controlled by a 555 timer setup driving a small relay; it turned on for about 30 seconds every 5 minutes, adjustable w/ a knob....

Evap was [b]far[/b] more than we needed for 15 people.

Changes for this year is to dig a slightly larger sump (3" deep x 1' square or so), and
to remember to bring the bleach this time... and solar powered battery charging this year!

Come by and check it out at blacklight aquarium...

- Bart

[IslandTartan]

First off, hello to all of you lovely people, i've enjoyed reading this thread to see the creativity that's at work. An idea occurred to me, and if it's already been raised I apologize for taking up space but I didn't see it in earlier posts. Would at tier system allow you to evaporate more liquid as it would increase your surface area as well. The thought is like a fountain where the topmost disk is of a specified diameter say 1 foot, with the successive lower diameters being 2, 3, 4 feet. I hope I haven't been too vague and was just wanting to see if it worked. love and light...

[ibdave]

First off, hello to all of you lovely people, i've enjoyed reading this thread to see the creativity that's at work. An idea occurred to me, and if it's already been raised I apologize for taking up space but I didn't see it in earlier posts. Would at tier system allow you to evaporate more liquid as it would increase your surface area as well. The thought is like a fountain where the topmost disk is of a specified diameter say 1 foot, with the successive lower diameters being 2, 3, 4 feet. I hope I haven't been too vague and was just wanting to see if it worked. love and light...

Yeppers, you got the right idea, but the trick is to size it right for the camp size... Also if it's to large you will have other camp asking or in some case just dump their own greywater into yours..Then you ge stuck at the end with extra water.. We cut of showers the night before to insure we were down to very little water at the end. It worked great.. Adding solar power this year.

Black plastic, black plywood, hardware cloth and 12 volt bilge pump and your good to go...

[bigbluedoggy]

I love this concept, as we were stuck with a smelly tarp full of unevapped water on Sunday last year due to the mild temperatures. I am going to try my own spin on this and use something like a dual pool filter stack to maximize surface area. Two pumps pumping up thru 2 or 3 level 3' dia. plywood discs, each with numerous holes to allow trickle down to the lower levels in addition to the hardware cloth on the outside. The stacks will be shorter to maximize the flow capability of the two solar pumps. The whole thing in a raised, lipped plywood platform lined with visquine and having two recesses for the pumps to create sump areas. Think it should work pretty well. Depending on load, we will either run one or two pumps. Add a little bleach and run all kitchen water thru a strainer and cloth to get the worst nasties out. Stop by Destiny Lounge and see how its working! Thanks for the wonderful info on here!!

[ibdave]

I painted the plywood flat black to heat up the water...

[blissmonkey]

[quote="Dork"]We need a name for these things so Mr. Polando and El Subcomandante Marcos are suitably honored for freeing us from the tyrany of ineffective evaporation ponds. Suggestions?[/quote]


El Vapo

El Vapondo (my fave)

El Vapondante

El Vapolandato

[bigbluedoggy]

El Marco Polo?

*WOof!*

[IslandTartan]

*Raises hand for "El Vapondo"!!!!!!

[tastybite]

This thread has been great inspiration...

I saw a beautiful system on disply at the "prepare for the playa" event in SF last weekend, and that's got me wondering if pumps of 500gph+ might be too powerful? It seems that the slower the water moves through the system, the more efficient it will be in evaporation. I'll be in AEZ this year, and want to build a system that will use as little power as possible. Our camp will be 18 people, and I'm estimating we'll generate 20-30 gallons of grey water per day.

The system I saw demo-ed was using a subaru fuel pump (looking into downsizing to a motorcycle fuel pump)...but I'm having trouble figuring out how much power these use??

Anyone have any recommendations for a low-power pump that will trickle water through the system, rather than having it blast out through the top (which seems like waste of energy)?

Cheerios!
--Tastybite[/img]

[bigbluedoggy]

How about a "no-power" pump? I just got a couple of these for my new evap this year: http://www.siliconsolar.com/Night-Solar-Fountain-Plus-p-16235.html 40-50 gph in a 2' lift. I also am of the mind that the slower the trickle factor in the dispersion, the more rapidly the water will evaporate from the surfaces. The link for those pumps was actually pasted earlier in this thread. I got two for redundancy and am planning on a double fountain setup with two "stacks" but shorter than the ones pictured in the thread. Stop by and see how its working! Good luck!

Doggy *WOof!*

[motskyroonmatick]

My 500 GPH 12 volt sump pump draws only one amp of power and covers the hardware cloth with water but does not flood it. I think it is the minimum for most efficient evaporation. There will be a point of diminished return both at high flow and low flow for evaporation and power useage. Since my evaporator runs a realtively small ammount of time I have the benefit of being able to store excess power for other camp uses and have higher capacity. I really like how people are mutating this idea to fit their needs and resource use concerns.

[desert dog]

I agree with a much earlier post that to make this more efficient the water has to flow over a large surface slowly and maintain airflow thrugh the material.


The hardware cloth used in the design works fine for high water flow. A more effieicnt design would be to use a porus material like the media that's used in a house humidifier or a swamp cooler. I think you could do this with a low powered solar pump and a little wind.

[Don Gately]

How does the width of the hardware cloth squares affect evaporation? I tried a thought experiment:

small squares=divide water into small units, so more surface area

large squares=greater water:wire ratio, so more surface area

Result: Inconclusive. In practice, which works better: large squares or small squares?

[Dark Gnome]

Here's a pic of the evap pool KernelSander speaks of, fully deployed, and complete with 'Art Ducko' to pay homage to 2006's theme:


Here are 2 more:
http://www.blaqua.com/images/misc/06_evap_02.jpg
http://www.blaqua.com/images/misc/06_evap_03.jpg

We're at Habitat and 7:30 - look for the big-ass spinning fish sign.

We used a bilge pump last year to very good effect - no more shower restrictions due to evap issues! We used a very small pump and constructed an A-frame from 1/2" EMT; a 4" diameter piece of ABS pipe along the top of the A-Frame with end caps distributed the water through holes drilled in the bottom on each side. The A-frame was covered in greenhouse cloth. The pump was controlled by a 555 timer setup driving a small relay; it turned on for about 30 seconds every 5 minutes, adjustable w/ a knob....

Evap was far more than we needed for 15 people.

Changes for this year is to dig a slightly larger sump (3" deep x 1' square or so), and
to remember to bring the bleach this time... and solar powered battery charging this year!

Come by and check it out at blacklight aquarium...

- Bart

[ibdave]

bump....

[swampdog]

Here's my evap experiment. I found 200 ft of black 1/2 in pvc hose (like used for ag or home drip/sprinkler systems) at a big box hardware store for $15. I've got 2 systems - one for dish/other water, one for shower. The shower is a square plywood base (with 1 long (+1") leg and the diagonal leg short (- 1") which should make the water tend towards the drain. I'll put a PVC frame on top of that to hoist up solar shower bags etc.

The dish/other supply has a tub that I got for icing down drinks in the top (filter) of a 32 gal trash can (reservoir). In the tub (filter), I'm going to put layers of gravel, sand, and screen-door screen (with a removable screen door screen piece at the top for the big chunkies) with drain holes at the bottom to drain into the trash can (reservoir). The reservoir sits up 8" or so on some scrap blocks I found so that gravity should drain it.

Each drain feeds into one of the 200' sections of ag hose. I figure, 200' of hose means about 100 sq ft of sun exposure at a 1/4" depth equivalent. So the water oughta come out of there pretty hot - assuming I can keep it coming thru slowly. So the two heater coils Y into a connection for a garden soaker hose which should drain very slowly into a smallish evap pond, where it oughta evap pretty damned fast. In case the soaker hose gets all plugged up (not unlikely) I've got valves all over the place that I can theoretically use to limit the flow and a sprinkler head for final exit.

In theory? Gravity fed, low maintenance, not very expensive, high evaporation rate. In reality? Ask me next week! I've tested the concept generally (water will drain thru the system) and the only prob I had was that I had to prime the 200' hose - gravity wasn't enough to get the water started all the way thru the system. I got 2 little pumps that you run with a power drill that should be enough to prime the system once or twice a day if needed.

Yes, I'm covered for plan b - increase the size of the evap pond. Although the filtered water ought to be pretty damned clean and sprinkle-able if worse come to worst.

If this works, I'll post plans (ha!) and pix to clarify. I'll be at Boogie Universal ARTS collective camp, 9 and esplanade, if you want to check it out on playa and celebrate my success or laugh at my failure.

[backbone]

Second year with the identical system that I used previously, and I had the same results.

It worked like a champ and withstood the high winds without being reinforced with any additional guide wires.

Plans for next year.

Have a grey water fountain art piece. The sound of running water is very soothing and relaxing.

Water treatment system to reuse the shower water for full body bath tub soaking luxury.

Design a system to handle 500-1000 gallon a day evaporation/recycle water treatment camp.

[barnz]

So my first burn in 2006 resulted in my carrying back tens of gallons of icky icky water from my camp of 10 people. Something leaked in the car, and it's never been the same.

After reviewing all of the impressive plans here before the 2007 burn, I was talked out of any of the pump-based designs by my camp-mates (the same people who 'handled it' the year before!

I did sell them on the Clothesline idea, (using old cotton T-shirts to dip in the pond and then pull up in the air to evaporate). And although our setup was rinky-dinky in the extreme, (two saw horses with rope tied between them, water bottles for ballast) I have to report that from an evaporation standpoint the system worked really really well. We didn't even get it set up until after the storms, so it's not like the excessive winds were much of a factor.

Initally our camp had a nearly identical pond system set up as last year, but instead of (not) handling the water of ten campers we had thirty, people to deal with, including mostly first timers, who weren't familiar with either the GI Shower or the Whore's Bath concepts. (Oh, plus the neighbors who were enthralled by our mucho macho shower structure. They seemed to feel that as long as they brought more water, they were entitled to use it. I had to go have a friendly conversation about carrying that water back to Texas once they were "done with it!"

After adding the clothesline system, and dipping the rags only occasionally (I don't think any of my campmates paid any notice besides me!) There was no grey water to carry home this year at all; just the plastic tarp with dried crud to fold up and toss out.

I have to recommend it. We could have done with a much smaller pond, for one thing.

One note to those who will try it next year: all that sopping-wet material is heavy. Make sure your clothesline structure is rugged, and easy to dip and pull back into place. I'm thinking about a circular design with concentric rings of clothesline that could fit a kiddie pool...maybe raised and lowered with a pulley like an outdoor umbrella...?

[stargeezer]

There are several issues that can improve this system, but not wanting to complicate it more than necessary I will simply state that use dark breathable material. The darker the better for solar collection, and breathable like towels add to the evaporation rate.

If you have someone responsible for keeping the material damp, you can evaoporate in excess of one gallon per square foot of material per day. This does not sound like that much, but a single two foot by four foot towel can evaporate at least eight gallons per day. With several towels, it won't even take the full day to get rid of huge amounts of gray water.

As a side note, please be sure to filter any solids from the gray water before using this system to prevent unwanted moop from being created and a pain to clean up. Used panty hose make a great filter as you can collect all the solids and dispose of them properly.

[barnz]

...be sure to filter any solids from the gray water before using this system to prevent unwanted moop from being created and a pain to clean up. Used panty hose make a great filter as you can collect all the solids and dispose of them properly.

We did this with 5 gal paint buckets, and it was reasonable effective. The top of my list for next year's improvements is further filtering (perhaps a charcoal/sand/gravel bucket) and better compost drying.

[stargeezer]

I am just sitting here looking at the aerial shot of the city, and an interesting idea has popped into my head. This is NOT playa tested, but is simply food for thought.

Looking down on the city, I notice a very large number of dark fabric shelters that seem to be calling for a new usage. The first item that must be addressed before proceeding too far is you must have:

A good filter system
Good preasurized low volumn flow control

The above items are both easy, I will leave the implementation to your imagination.

Now, rather than having a dedicated evaporation area that others tend to pollute, gather, filter and contain your grey water is some storage vessel. Pump this water at a very slow rate and distribute it over the fabric of your shelter. This flow rate must be slow so the surface tension of the water keeps the water in the fabric, rather than creating drips which rain on the inside. You want the flow rate slow enough that the water wicks its way down the fabric without running over the edge of the shelter, and in fact the edge should be dry.

What I have described will provide two benefits, first it will evaporate all that unwanted grey water, and it will help cool the structure.

Yes, if done incorrectly, this will make a big mess. I am not suggesting everybody should try this, but for those with the proper skills, it is a very simple solution.

Just so you don't think I am totally crazy, imagine ten 1/2 GPH drippers spaced around your structure to spread the water out, and this system is pressurized for ten hours per day. Even in this small example, that is 50 gallons of water evaporated every day, and the big structures have surface areas that would tolerate a lot more than the ten drippers.