Closed loop recycling of flush water through ABR and Constructed Wetland?

  • canaday
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Closed loop recycling of flush water through ABR and Constructed Wetland?

Hi everyone,

I am looking for cases of direct reuse of processed blackwater for flushing the same toilets again. This would resolve many problems at the same time:
-- People can use the same flush toilets that they are used to.
-- Demand for water would be greatly reduced.
-- Pharmaceuticals and other contaminants that cannot be entirely removed during treatment do not go into rivers or anywhere else in the open environment.

This would be safe and acceptable because:
-- Biological treatment (e.g., ABR + CW) reliably eliminates pathogenic bacteria, smell and color.
-- Users would not have contact with this water.
-- Those who clean flush toilets already apply precautionary measures, such as long-handled brushes, gloves, etc.

It seems that the only real obstacle is people's linear, disposable, one-use, throw-away mind-set.

This would involve some additional piping and pumping, the latter of which could be done with pumps that also serve as exercise equipment, such as Treadle Pumps
(
)

So far, I propose processing the blackwater in ABRs (Anaerobic Baffled Reactors) for 24 hours (and maybe recover biogas), then at least 3 days in a Vertical-flow, Subsurface Constructed Wetland. All suggestions are welcome. (The idea is for there to also be UDDTs that users can opt to use if they prefer.)

I am proposing this to an institution here in Ecuador and would like to find more support for this, especially up-scale applications where people are doing this with no problems.

This would be true / re use /.

Best wishes,
Chris Canaday

Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
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  • AquaVerde
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Re: Closed loop recycling of flush water through ABR and Constructed Wetland?

Dear Chris,

Under our "cold" condition, my close colleague Mr. Pollmaecher is doing this kind of "up-scale applications" for him self (6-8 pe) via AV-ABR, vCW (4m2/pe), slow sand filter (cascading), Koi-fish pond/swimming pool, using the wwtp effluent outlet water for pond, wash-machine, WC and vegetable garden and tree irrigation. He needs supplementing with rainwater. In other words, his property do not "supply" sewage to outside.
See: aqua-verde.de/bilder-galerien/nutzwasser...ur-abwasser-kosten/#

AV-ABR and vCW:

Slow-sand filter:




The wwtp-effluent do not have any e-coli's at all.

I hope this helps... :)

Mr. Pollmaecher is a very "handy man" (DIY)!
I would not suggest this kind of systems for any kind of lazy "users", just maintained by bad paid domestic care takers (gardeners).

All the best
Detlef

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Re: Closed loop recycling of flush water through ABR and Constructed Wetland?

Dear Detlef,

Thanks for this spectacular example. Many, however, would be worried about pharmaceutical drugs and potentially even normal, natural human hormones.

I would like to find cases where the flush water is processed and then recycled as flush water, again and again, especially at a large, public institution (and preferably with normal employees and not only super DIY homeowners).

Reclaimed Water, after wastewater treatment, gets used even for drinking water in more and more places in the world.
en.wikipedia.org/wiki/Reclaimed_water
(This is a wikipedia page that could stand some serious editing.)
This is much more worrisome, in terms of pharmaceuticals, etc., than using this reclaimed water for flushing toilets once again.

Why is this not standard procedure? Why is it not listed among the options in the Eawag Compendium? Is there any reason not to do this, beside people's mindset?

Best wishes,
Chris Canaday

Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
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Re: Closed loop recycling of flush water through ABR and Constructed Wetland?

Chris

yes it does seem sensible to re-use blackwater as toilet flush greywater (after on site processing) in a continual loop, topped up as required from rainwater collection systems, other greywater diversions or mains as the case may be.

How much treatment and to what level of pathogen kill is required for this type of re-use? 100% or lower?

I guess the question is (for most settings), can it be done at household level with a system technology that is low cost, low maintenance, low impact and has a low "behavioural change? requirement?

Perhaps can be designed for commercial settings as a scaled up pilot then "slimmed down" for households?

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Re: Closed loop recycling of flush water through ABR and Constructed Wetland?

Dear Chris,

On the example of Mr. Pollmaecher's blackwater ABR-CW + slow sand-filter all on gravity, you may skip the swimming pool/koi-fish pond to may have a much simple system you may looking for, which will run for years without any maintenance. Gravity systems need a pump for reticulating water. At least this pump needs maintenance sooner or later. If you give any system to people who are not see a DIRECT benefit for them self, they will not maintain it. Maybe a hotel/resort owner will not be a lazy "user" and will have economical interest in it and will organize regular maintenance through low paid care-takers.

My own greywater-CW and reuse-system for WC, garden and washing-machine did no "produce" enough water. Maybe I am smelly and do not wash my self enough ;-). I had to top up with automatic rainwater blending and in the beginning to maintain it very often. E.g., I redesigned it partly, taking off all the "security against clogging" (pre-filter)in front of CW. At the moment, after 6 years the automatic rainwater level switch is broken as it was permanent exposed to tank-moister.

Having this experiences by my self it told me, it needs much-much more simplified systems (low-tech) as I was doing it as a so called low-tech water-"expert"... ;-)

Good luck
Detlef

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Re: Closed loop recycling of flush water through ABR and Constructed Wetland?

Dear Dennis and Detlef,

Dennis, the idea would be to treat this blackwater just as well as if we were dumping it into the environment, only never dump it into the environment, so maybe somewhere between 0 and 200 fecal coliform bacteria per 100 ml. It would be key to eliminate any smell or color, so users do not enough notice the difference.

Detlef, thanks for these details. I think with so much rain falling on the constructed wetlands here, we should be able to keep the same amount of water cycle after cycle, and there would be plenty of greywater that could be added whenever needed.

Best wishes,
Chris Canaday

Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
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  • HAPitot
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Re: Closed loop recycling of flush water through ABR and Constructed Wetland?

Dear Chris and others,

I got into this thread via the discussion started by Navenka about ecosan in Italy.

Chris: an intriguing idea: use water like a conveyer belt for excrements and keep it in a closed loop. How far have you reached with an implementation of your idea?

Unfortunately, I think this requires a lot of technology, certainly a lot more than you have suggested! The idea actually demonstrates the problem of mixing excreta and water together in order to move the excrements. It's because water doesn't act like a more or less neutral conveyor belt - water and excreta interact: water picks up all the substances that can be dissolved, and they end up as dissolved solids in the water. So, you would have to remove the dissolved solids from the water in order for the idea to work, and that requires a lot of technology (like membrane filtration).

What I think would happen in a closed loop with the technology you are suggesting is that the water would pick up more and more dissolved solids as it is recycled until saturation is reached for the substances that can easily be dissolved from excreta, and that would probably have two effect: you'd have a lot of problems with precipitation in the piping of all kinds of dissolved solids, and the plants in the constructed wetland are likely to die of an overdose of salts (and even some of the microorganisms may die).

So, 'this conveyor belt' cannot work in a closed loop with simple technology unless some of the water is discharged in order to remove dissolved solids. But it can work, if gray water is included as shown in the example that was presented. And I would think that there are more examples like that. But for most people, it would boil down to costs - the costs of fresh water to flush the toilets as opposed to recirculating part of the effluent from the treatment facility.

But I think the idea is neat because it demonstrates some of the principles of ecosan and sustainable sanitation:
1. Avoid mixing excreta and water.
2. If you do, reuse the mix of water and dissolved solids as 'fortified water' for irrigation (rather than trying to separate them).
3. Make sure medicines are biodegradable and are not harmful to the environment. Don't use amalgams containing toxic metals (mercury) for filling teeth.
4. Make sure all other household products, detergents, etc. that are getting into the water are also biodegradable and not harmful to the environment.

Especially the point concerning medicines (#3) would still need a lot of awareness raising in the medical community and in the general public.

Wow, that idea has really fired up my imagination, and I hope you'll find something useful in these thoughts!

Thanks,

H-A

Hanns-Andre Pitot
M.Eng. Environmental Pollution Control
presently in Seesen, Germany
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Re: Closed loop recycling of flush water through ABR and Constructed Wetland?

Dear Hanns-Andre,

No, I have not had the opportunity to put into practice Closed-loop Blackwater Recycling, but I am looking.

I have searched extensively on the internet and have asked all of the members of this Forum, but apparently this has never been done before. One of the closest cases is the Solaire Building in New York City, where they reportedly treat all their wastewater and some of the reclaimed water to flush toilets, but part is also used for cooling and irrigation, so this is not Closed-loop.

I am confident that the technical aspects of this will not be as complicated as you suspect. If it were to get too salty, plants that withstand seawater could be planted in the Treatment Wetland. I have built numerous Vegetated Sand Filters in which the effluent is visually and olfactorily indistinguishable from tap water.

The microbes and the plants have a great capacity to adapt to different conditions. In addition, with the accumulation of pharmaceuticals, the microbes will certainly evolve to be more and more efficient in breaking them down. Solids should remain almost entirely in the ABR, where they are converted into biogas. Maybe a membrane could be added, but I do not think it would be necessary.

Yes, this would encourage people to avoid using toxic chemicals in the house, rather than the current flush-and-forget paradigm.

Do you know of a case where we can implement this first?

Thanks for the encouragement.

Best wishes,
Chris Canaday

Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
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Re: Closed loop recycling of flush water through ABR and Constructed Wetland?

There is a similar problem with the recirculation of process water in some designs of biogas facilities (where the effluent is dewatered and and the solids are composted), and what I can tell you is that they cannot run it completely closed loop. If I remember correctly, it's because ammonium is accumulating in the water to the point that beneficial microorganisms are dying. Of course, in your system, the wetland will tend to convert ammonium into nitrates or even molecular nitrogen, but I would see similar problems coming up. In any case, you can try, and if it doesn't work, you can always use some of the treated water for irrigation.

I wish u good luck with your project!

H-A

Hanns-Andre Pitot
M.Eng. Environmental Pollution Control
presently in Seesen, Germany
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Re: Closed loop recycling of flush water through ABR and Constructed Wetland?

Dear Hanns-Andre,

I am "passionate for low cost and resource recovery" too, in my words "einfach" (simple) and "stromlos" (low-tech without external energy).

A 100% closed system with recovery of all components is with "low cost" (einfach) not possible, to have it in space stations it is high-tech and costing millions.

To keep low the resource consumption of construction material, a open system is necessary, which is recycling only parts of the most wanted components. It is depending on the needs, some times nutrients, some times only water for irrigation and so on. On the later you can see example pictures of my colleague Mr. Pollmächer above (for my taste, he still having to much resource consumption of construction material).

In small scale projects an ABR as first step is often overdone, as simplicity is lost and resource consumption for construction material is too high. In large scale, like in Saudi Arabic ABR is the right choice. In this very large scale case THE WATER was more important then nutrients and energy (biogas) use.

In my opinion the two stage CW (incl. sludge-humification) keeping ALL strictly aerobic, by Dr. Käthe SEIDEL is the most simplified (einfach) water recovery system. E.g., if you need more nutrients for irrigation just skip second stage or keep second stage very small and so on...

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Detlef

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Re: Closed loop recycling of flush water through ABR and Constructed Wetland?

Dear Sir,

Your conclusion that a closed-loop, zero-discharge system is financially impossible I ASSUME is based upon a co-mingled wastewater stream, i.e. blackwater and greywater combined and then trying with financial and energy wise difficulty to separate and reuse or recycle the nutrients and/or the water.

I agree, but if you separate and compost the toilet, as well as ALL organic kitchen RESOURCES, not wastes utilizing a no-energy Bio-Matter Resequencing Converter (BMRC - Composting tank with vermiculture)you end up with reusable liquid and soil fertilizers. You do need a carbon source, which can also be a waste source such as pine bedding or leaves.

Now, we have the remaining greywater, which in a household situation, (300 gallons per day) utilizing an 80 watt linear air compressor and three tanks in series, aeration/surge, then more aeration and then settling you end up with greywater acceptable for at least subsurface irrigation.

With a very minimal amount of energy for a pump to provide 60 psi, a SpaDepot, $134.00 ozone generator and a $125.00 Home Depot reverse osmosis under the counter system you can recapture 95% of the recycled greywater because all of the nasty minerals and any small amounts of pollutants re-introduced into the reverse osmosis greywater from the bathroom, kitchen and laundry is not only possible but also environmentally logical.

The paradigm shift needs to be the acknowledgement that combining blackwater and greywater for simplicity is, as you conclude, impossible mentally as well as financially.

We have been proving this concept in Minnesota for over 10 years with documented data.

Clint
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Re: Closed loop recycling of flush water through ABR and Constructed Wetland?

Dear Clint,
Well done and I agree with you too, just for your very technology advanced country.
Regards,
Detlef

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