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grey water system design for cold climate

 
Levente Andras
Posts: 153
Location: Harghita County, Transylvania, Romania
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Hello Permies !

I have been planning the grey water system for my semi-rural property in Transylvania, Romania, and two somewhat different solutions offer themselves - I will need to decide which route to take. I thought I could share these and hear your opinions with regard to pros and cons, and perhaps possible tweaks - and even alternatives?

Background: the property is in zone 5, continental climate (cold winters - temperatures of minus 20 degrees Centigrade are not uncommon, hence in winter, water running on the surface quickly turns into ice, and some elements like constructed wetlands have limited efficiency). Soil is heavy clay, with poor percolation.

The objective is to re-use the household grey water for garden irrigation, and/or turn it into water that is suitable for a small wildlife pond

I have read Art Ludwig's book on grey water, found it very useful and interesting, but the solutions he describes are not wholly suitable for my climate or my situation - although the general principles and some of his ideas were helpful in getting me started on my design.

What resonated with me was the TraiSelect system proposed by Jozsef Orszagh - see http://eautarcie.org/en/index.html or on YouTube https://www.youtube.com/watch?v=r7efH9DVlws

The two solutions that I'm weighing at the moment are:

(a) an (adapted?) Traiselect, consisting of a grey water tank ("batch reactor" - basically a septic tank where the grey water is pre-treated through anaerobic purification ); an aeration tank; a planted trench filter; and a constructed wetland or pond.

(b) a system consisting of an underground concrete chamber filled with mulch (straw, wood chip etc.), possibly also charcoal, which would act as grease trap and initial filter; and a constructed wetland possibly two (water "cascading" from the one into the next); and a pond or tank where filtered water collects. Between the concrete chamber and the constructed wetland I might include a winding gravel swale to provide extra filtration and aeration. A similar system is described here http://eautarcie.org/en/temoignage-andalousie.html

Note that system (a) expressly excludes the use of a grease trap (the grease film that forms on the surface inside the "reactor" has an important role); and that it requires a pond aerator which (I assume) is an air pump not very different from the ones used in an aquarium. So technologically slightly more complex than system (b). It seems to me that the aerator is a nice-to-have rather than an essential element, and could be dispensed with.

I am slightly more inclined towards (b) because of its seeming simplicity, and because (a) involves the use of the "reactor" which (pardon my ignorance) I have not seen used like this before - besides, the reactor has grey water sitting in it for a relatively long time, which in Art Ludwig's book is a mistake (although I do suspect that this is a different concept from grey water just collecting in a container).

The downside of system (b) is probably the long pathway that the water has to cover between the initial filtering and the final destination, and hence the larger loss through evaporation.

I would be extremely grateful for any thoughts / ideas / suggestions !

Levant
 
William Bronson
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Location: Cincinnati, Ohio,Price Hill 45205
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Sherry Jansen
Posts: 59
Location: Southern MN
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I have been looking at Sand Filtration for our grey water-


Then, once clean, it be used for nearly everything except for drinking. If you heated the water it could do dishes, laundry or, flushing toilets, though most people don't make enough grey water to use for the water wasting toilets so maybe get a SeaLand toilet with a compost toilet system?
 
S Andow
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I think the Sand Filtering tanks are ideal, and to add to the efficiency I would add some additional filters-
First, the top filter should be able to be taken out and burned (?) as this is the catch-all filter.
And, on the bottom I would add a charcoal filter.

That said, a large sand filter seems to be the best solution to northern climate greywater systems. The filtered and cleaned water can then be used for watering plants or garden/yard.
 
Levente Andras
Posts: 153
Location: Harghita County, Transylvania, Romania
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Hi guys,

Thanks for your replies / posts regarding sand filtering and other solutions.

I have some doubts about the efficiency and even suitability of sand filtering for a grey water system

I do see S Andow's point about a 'catch-all filter' (I called it grease trap) - this would catch some of the grease and the rough particles that float in the grey water. For this you can use mulch of some type, which you can remove periodically and compost (rather than burn).

HOWEVER, I don't think that grey water that exits such a grease trap would be suitable for sand filtering. It would still contain a fairly high amount of grease and solids that would quickly clog up your sand filter and render it useless within a short time. Thus you will need to wash (or replace) your sand filter several times a year (=not practical).

More importantly, I believe that trying to pass grey water through a sand filter is an overkill. Your goal is not to obtain pure water that's suitable for drinking (as in the video that Sherry Jansen posted), but water that is suitable for, say, (a) a wildlife pond; or (b) for storage, e.g., in a cistern, so that you can use it for watering crops when needed, rather than when produced.

If you had a system that took your grey water directly to the veg bed or tree that you wanted to water, you might not even need to filter it at all, except if you were concerned about pipes clogging up with solids. I'd like to go beyond that, i.e., I'd like to be able to use the grey water only when and where needed - hence I would need to store it, hence it would have to be 'filtered' or treated to some extent, before it goes into the storage tank.

Any further thoughts are still welcome !

Levente

 
Feidhlim Harty
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Posts: 158
Location: Ireland
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Hi Levente, have you considered a constructed wetland system or gravel reed bed system at all? These would filter the grey water and then you could store the final effluent in a pond as a reservoir for use in the garden. For a typical Irish house I'd estimate a size of about 50m2 for a constructed wetland or half that for a gravel reed bed. This will get the final effluent relatively clean - but by no means drinkable. For irrigation of edibles, you need to be sure that you're happy with the ingredients in your cosmetics, shampoos, soaps, cleaners etc. Buying all your stuff in health stores is a good start - but no guarantee of perfection.

Wetlands and reed beds have been used in cold climates; the residual warmth helps them to stay thawed for most of the year. Have a look into this more if you're worried about frosts.

I'd still recommend a grease trap first. The soil based constructed wetland has the advantage that solids don't really cause problems. For other differences have a look at www.wetlandsystems.ie/reedbedsystems.html

Another thing to do is the Oasis Design approach and just use willows or some good local tree as a firewood crop.

Be sure to follow local codes so that you don't have to undo hard work.
 
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