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How to set up phytodepuration?
Easy to maintain and more economical than a septic tank, phytodepuration is an autonomous and ecological solution for individual wastewater treatment.
Particularly suited to rural areas not connected to the mains sewage system, this purification process is easy to install, inexpensive and even has the advantage of being aesthetically pleasing.
Ideal for a plot of land intended for a Tiny House, self-build or not 🙂
In this article, we explain how phytodepuration works and how to build one yourself.
What is phytodepuration?
This is a natural process using plants to filter and purify wastewater.
Totally ecological and odorless, phytodepuration consists of purifying wastewater using bacteria present in the roots of purifying plants (bamboos, reeds, cattails and sedges are the most commonly used).
How does it work?
Nature takes care of everything. Bacteria present in plant roots purify the water.
These bacteria are aerobic, meaning they need oxygen and don’t give off unpleasant odours. They transform organic matter into mineral matter, which can then be assimilated by plants.
In exchange, the aquatic plants provide the oxygen needed by the bacteria via their roots.
These plants adapt to all types of soil and to different times of year. They can withstand both wet periods, when the house is occupied, and dry periods, when the house is empty.
Another advantage of this wastewater treatment system is that it is odorless.
Why? Because, unlike a septic tank, which follows the same principle as fermentation in a confined, oxygen-free environment, where incomplete decomposition generates gases and sludge, phyto purification is based on the same principle as composting. In contact with air, decomposition is complete, producing organic matter (humus and water vapor).
It should be noted, however, that when the planted filter system is first installed, the sand will not be overgrown with reeds and may give off slight odours. But these will disappear as soon as the reeds have spread over the entire filter surface!
Another question mark over the operation of a phytoperutaion: winter frost. Here again, there’s nothing to worry about! The plants installed are naturally present in water bodies and therefore frost-resistant. What’s more, the constant supply of water to the plant purification system limits frost formation. Finally, if there is frost, it will only be on the surface, as underneath the bacteria will continue to work, creating energy and therefore heat.
The 3 stages of phytodepuration
1. Pre-treatment
In the pond, the pebbles and reed roots leave the macro-particles on the surface of the water. The other elements will be transformed into compost.
2. Chemical compound processing
The purification plants installed in the pond draw out nitrates, phosphates and metals. During this2nd stage, the pollutants, which are essentially household, are broken down.
3. Biological water treatment
Compost stored at plant root level will be “eaten” by the bacteria, transforming it into mineral matter on which the plants feed.
Phyto-purification maintenance
With the exception of “gardening” maintenance such as mowing, weeding and cutting the reeds once or twice a year, there’ s nothing to do!
Simply plan to rake off the top layer of compost every 10 to 15 years, which can then be used as fertilizer for the rest of the garden.
This low maintenance requirement is one of the reasons why the planted filter water purification system is more economical than a septic tank.
| SEPTIC TANK Family of 4 to 5 persons | PHYTOEPURATION Family of 4 to 5 people | |
|---|---|---|
| Set-up costs : | Approx. €6,000 | Approx. €4,500 |
| Interview: | Paid, maximum every 4 years by a professional | Free, gardening once or twice a year. |
| Installation time:! | Maximum 20 years if well maintained | About 25 years |
And don’t forget to find out about zero-rate eco-loans and other assistance available to you when installing a plant purification system. Information on Ministry of Ecological and Solidarity Transition.
Installing your own phytodepuration system
The installation of a planted filter sanitation system can of course be carried out by a professional, but public services also allow you to install it yourself, by following these guidelines:
“The commune (or, in certain cases, the commune or agglomeration community) examines the design by studying the file provided by the owner, supplemented by an on-site visit if necessary. It also verifies the installation’s execution on the basis of the preliminary design review and during an on-site visit prior to backfilling. This examination is carried out by the Service public d’assainissement non collectif (SPANC).
Non-conforming installations must be brought into conformity within 4 years in the event of a proven health or environmental risk. This period is reduced to 1 year in the event of sale of the building or house.
The owner must maintain the system regularly (servicing, emptying).
The SPANC checks the correct operation and maintenance of the installation at least every 10 years. Click here to consult the regulations governing wastewater treatment.
In terms of installation surface area, plan on around 24m2 of phytodepuration ponds for a family of 4/5 people. This natural sanitation system will be built according to the principles of vertical and horizontal filtration:
Vertical filtration by plants :
Wastewater is conveyed to the 1st basin, where only reeds are planted. These plants are unique in that they produce a lot of oxygen, enabling maximum bacterial growth.
What’s more, the movement of these light plants will prevent the waste transformed into compost from clogging the gravel filter.
Then, in the last basin, other plants are used for more precise filtering.
Horizontal filtering through basin layout:
At the beginning of the conveyance system, the wastewater is filtered through a screen to recover the larger waste.
Gravel and sand in increasingly fine gradations are placed in each basin to filter the water horizontally. A drain is also installed to evacuate the water.
To allow water to drain naturally, the1st basin is located at a higher level than the second. This means that your plot of land must be at least 1 metre high for the installation of the phytodepuration system. If this is not the case, you’ll need to install a lift pump to transport the water from one basin to the other.
For more technical details on the installation of a phytodepuration system, we recommend that you consult the magazine La Maison Écologique N°115.
Do you have an alternative housing project? Would you like to start a self-build project? Take a look at our Casakub layout plans 🙂.