Phytoremediation is the use of aquatic plants as depollution agents to counter the damaging effects of human activity on the ecology.
This "phytotechnology, callled phytoremediation, has been the subject of many vast research programmes throughout the world since the 1990s. On the one hand, it helps to clean and preserve essential ressources like the water, the soil, and the air in a particular zone, and on the other hand it reproduces greenery which is beneficial for the landscape and for biodiversity, making it pleasant for the inhabitants. It also has ecomonic advantages.
Every type of pollution has a corresponding combination of intelligent aquatic ecosystems and different substrates ( pozzolanic ash, sand). Planted filters, macrophyte basins, and humid forests allow superior vegetation, micro-organisms and various substrates to combine their natural purifying capacities. Many hundreds of useful plants have been identified throughout the world : reeds, bullrush, willow, iris, etc. stimulate biodiversity. While growing, they absorb the elements necessary for their development (copper, zinc, phosphorous, nitrogen, carbon..), they produce oxygen, which will then decompose organic pollutants (phytodegradation), or even neutralize some more poisonous pollutants. Their application is therefore almost limitless : we can treat waste household water, industrial waste which passes through the plantations, or even create natural swimming pools, filter rainwater, and so on...
"The phytoremediation is implanted in the Nanterre island park to purify the water of the river Seine. This process was developed by the Phytostore company"
The bullrush is a very sturdy plant which can be used against the worst forms of pollution. It can depollute even the most extremely polluted waste water (liquid manure, water from rubbish tips). It works well in areas with almost no oxygen. It biodegrades petrol products from HAPs (Hazardous air pollutants) and chlorine components very well, and it resists everything : heavy metals, salts, surplus from COD (chemical oxygen demand) and BOD5 (biochemical oxygen demend).
Carex, or sedges, are a family of over 2000 species found in regions all over the world. It is a plant which is very powerful in phytoremediation. It can treat polluted water, soils (even radioacive) or air. Its acidic roots, active all year round, work efficiently against most germs and viruses (disinfection) and capture most heavy metals.
The reed is the filtering plant most used thoughout the world to depollute waste water, whether in the form of an alluvial vegetal filter or in the form of a planted basin. As it transports pure oxygen in its rhizomes, it is very effective in treating organic loads ( COD or BOD5 or SS -suspended solids). It is also now used to treat urban sludge.
The willow is an ideal plant for phytoremediation : its roots structure the soil and help the degradation of pollutants like waste water, leachates from rubbish tips, rainwater, soils and air. It is often used for the phytoextraction of heavy metals (depollution of soils). It also helps the evapotranspiration of effluents, thus preventing rejections from a treated site from spreading elsewhere.