Filtration treatment of gray water (shower)

[Bourdarie]

Hello,

I am a student and with my colleague we are working on a gray water treatment system. The goal is to use a certain amount of clean water (stored in a tank) to circulate it at the level of a shower then to treat it in order to make it drinkable and to reuse it again at the level of the shower.
We are thinking of setting up a diatomaceous earth filter first, then a block activated carbon filter, then to complete either a UV treatment or a reverse osmosis or ozone treatment.
We are not specialized in water treatment and the only information that we are are websites.

We would have liked to have advice, information and opinions on this idea.

Thanking you in advance

[Grelinette]

Before treating gray or simply waste water, it may be interesting to simply "sort" this water upstream to try to recover "clean" water.

Let me explain :

I was very surprised to see figures on the consumption of household water which showed that a significant% of water used was purely and simply wasted.

For example, to take a shower or wash your hands, in general we wait until the hot water arrives and several liters of pure water go down the drain.

When you brush your teeth or shave, unless you stop and turn on the water every time, several liters of clean water are still wasted.

In summer, to drink a glass of fresh water, let the water warmed by room temperature run until the water cools.

etc, etc.

The idea is to install a turbidimeter at the siphon at the start of the evacuation (sink, sink, shower, ...):

- if the water can be charged, or even clean, a two-pass system with solenoid valve directs it to a circuit for reuse (eg garden or wc) or subject it to a summary treatment,

- if the water is really charged, either it goes to the sewers, or to a heavier treatment circuit.

My research on turbidimeters had taught me that you could detect minute traces of a lot of substances even invisible in water (particles, bacteria, soap, detergent, ...)

[Bourdarie]

Thank you for your explanations. I agree with you that a lot of drinking water is used.
Hence the interest of setting up a water quality control system (turbidimeter) at the level of the shower drain and the adapted valve system.

Our specifications require us to reprocess "non-potable" water so that it becomes so.
After the water has been treated, it will be reinjected into the shower.
To answer this problem we have no budget limitation, but only a limitation on the size of the water treatment system which must be as small as possible.

We are thinking of setting up a diatom filter (obtaining a 4 micron filtration) and then an active carbon filter (filtration at 0.5 micron) but at the outlet it is still not potable. To make it drinkable, we plan to use either a UV treatment system,
or an ozone treatment system: after this kind of treatment we still don't know if the water is drinkable.
For reverse osmosis treatment, we assume that it is, but we are carrying out our study with the aim of finding a solution that quickly treats water, compact and environmentally friendly.


At our level we did not find any information on the quality of the water leaving the filters mentioned above.

[Grelinette]

Do the successive 4 micron and 0.5 micron filters not get dirty very quickly?

Household wastewater is very oily and very charged even if the particles are not necessarily very polluting (e.g. soap, shampoo, ...)

[Christophe]

In space what is used are osmosis units for the treatment of urine ... therefore the effectiveness is no longer to be proven cost is another matter ...

I'm not sure that a diatom filter is appropriate: it's voluminous and it will get dirty (very) quickly ... don't you think? A sand filter would be more adequate ...

But I think the individual treatment of gray water (sorry ... it's my opinion) is not worth the candle: at the current price of water (which is not a rare commodity with us) the econological (economic + ecological) price of filtration will never be profitable ...

A filtration system (less "heavy" than for gray water) on the recovery of rainwater would be much more efficient: some are already doing it ...

We have lots of topics on the issue, for example:

https://www.econologie.com/forums/recuperati ... e-t7.html
https://www.econologie.com/forums/filtre-et- ... t4297.html
https://www.econologie.com/forums/potabilisa ... vt157.html
https://www.econologie.com/forums/fabriquer- ... t3978.html

On the gray water side to avoid the sewer, there are lagoon systems ...

Also, there is also the question of recovering calories from gray water: hot water costs more than water ...

You can read this, it will please your teachers to extend the debate:
https://www.econologie.com/forums/recuperati ... t3674.html
https://www.econologie.com/forums/recuperati ... t6546.html

ps:

For example, to take a shower or wash your hands, in general we wait until the hot water arrives and several liters of pure water go down the drain.

With each shower that I take (or almost) I ask myself the same question, in terms of solutions; the instantaneous water heater would solve this water loss: but is it economically profitable? I have some doubts ... "cold" ...

This question deserves a subject all by itself ...

[Christophe]

Do the successive 4 micron and 0.5 micron filters not get dirty very quickly?

Household wastewater is very oily and very charged even if the particles are not necessarily very polluting (e.g. soap, shampoo, ...)

+1 I just made the remark: I think a sand filter would be more suitable (it's 20 to 50 microns I think) ...

bourdarie, are you sure that activated carbon is 0.5 microns? It seems small ...

By the way, how much is an osmosis unit?

On wiki http://fr.wikipedia.org/wiki/Osmoseur they speak of nanometer?

# the water is then pressurized and passes through the osmotic membrane, the porosity of which is of the order of millionth of a millimeter. Water is freed from 98% of its impurities.

Whatever, I think that whatever the filtration method (individual) the filtration of gray water is not interesting ... except lagooning ... but is it still filtration in the strict sense?

Well, it would be good to make an estimate of the costs of the different solutions per m3 of gray water filtered as part of your project ...

[Bourdarie]

Thank you Christophe and Grelinette for your explanations.

For Christophe, here is the link where I found 0.5 micron activated carbon filtration.
http://www.une-eau-pure.com/purificatio ... actif.html

However, the lagoon system will not be possible due to space constraints.
"Here it would be good to estimate the costs of the different solutions per m3 of gray water filtered within the framework of your project ..."

We are currently working on a summary table that I will put on this discussion for those interested.

An osmosis filter at 0.0001 micron according to the "SDWF" site.

Ok for the use of a sand filter to start filtration (approx. 40 microns) and then there is the problem ....

I realize that the idea of ​​reprocessing this kind of water is not profitable and that it would be best to use it after getting out of the shower as water for the toilet. But our subject does not offer us any alternative.
We must absolutely reprocess it!

So that solution choose a series of increasingly fine filter with a touch of uv to finish. We also looked at the side of reverse osmosis but as info we find that to get 1L of clean water it takes 4 to 5 L of water that can not be recycled so blah as a solution.

[Bourdarie]

Hello everyone, here is a summary table of the information that we found on the net.



Anyone have an idea on which filter to rely on to be sure that the water leaving is drinkable?

[dedeleco]

This water after a usual shower has especially soap, detergents and some human organic molecules of skin and others, like microbes and virus, but not more particles to filter, contrary to the water of a well often sandy and clayey.
Also the size of the pores is not crucial, but above all the ability to remove soap and organic molecules is essential.
So I would favor what removes soap and detergents, breaks down organic molecules, and disinfects, such as activated carbon, UV, ozone, bleach, pool products or chlorine, which evaporate after some time in the air.
A disinfectant that breaks down the soap is almost sufficient.
The difficulty is that there are a lot of soap and detergents to remove which will quickly saturate the activated carbon.
So a bed of fine sand followed by cheap activated carbon would fix most of the soap, or detergents, before an activated carbon filter and disinfectant and UV.
If the water is well disinfected, it can be used for a shower, but the detergents which remain and which are concentrated are troublesome for the eyes and the psychological effect of washing with the soap of the previous showers.
So you must either fix or decompose these detergents.
The activated carbon will quickly become saturated.
It must have a volume at least equal to or even greater than the volume of soap and detergents (shampoos) dissolved in the water and if someone spills their shampoo in this water, the activated carbon will be good to change.
So you need a cheap method that fixes or breaks down most of the detergents.
Living things, plants in the earth and lagoon realize this slowly for us.
Or a cheap activated carbon, which can be recycled by heating it yourself at high temperature, breaking down the molecules of fixed detergents (in an inert atmosphere of N2).
I give guiding ideas, but I am not a specialist in wastewater treatment plants which have cumbersome and time consuming methods.
See links with solutions:
http://www.aquae.fr/le-recyclage-des-eau-grises.html
http://www.eautarcie.com/Eautarcie/4.Ep ... grises.htm
http://www.eautarcie.com/Eautarcie/4.Ep ... lantes.htm
http://www.traitementdeseauxgrises.com/
http://www.traitementdeseauxgrises.com/ ... rosnes.pdf
http://assainissement-eaux-grises.over-blog.com/
http://fr.ekopedia.org/Traitement_des_e ... A9puration
http://www.eautarcie.org/04a.html
http://www.geo.fr/environnement/conseil ... tion-39025
http://www.ecoconso.be/Epuration-individuelle-des-eaux
http://master.cetmef.developpement-dura ... _usees.pdf
http://french.alibaba.com/product-cgs/g ... 03740.html
http://www.pareatis.be/documents/Filtre.pdf

[Bourdarie]

Thank you "Dedeleco" for your solutions and your internet links which will be very useful to us.
Everything that is STEP lagoon system ... is impracticable in our case.
We will therefore look through a sand filter then activated carbon filter then UV + at the output adding disinfectant.
we are now going to look for shower gels for those which are non-toxic, say "organic", which degrade more quickly. We will also look at the disinfectant level to see what we can get.

Thank you in any case for this info and we will get back to you quickly with the solutions or explanations that we have found.