Operation of the filter
Aquatic plants that grow in helophyte filters, with their strong root growth, ensure that phosphates and nitrogen are absorbed from the water, so that algae have less chance to grow and oxygen plants will develop better in order to improve the water quality. But the plants in helophyte filters not only make a major contribution to the purification, this is also done by the bacteria that live in the soil. The plants provide a good living environment for those bacteria. Numerous bacteria that need oxygen live around the roots of the plants. In flow fields and horizontally flowed filters, the plants act as a kind of oxygen pump that injects oxygen under the water surface via the roots. The bacteria convert waste products from the water into nutrients for themselves and for the plants. Furthermore, at the bottom of a helophyte filter, bacteria that live without oxygen are active. These feed, among other things, on the waste products of the oxygen-loving bacteria higher in the filter. In this way, the water is purified in a natural way, without the need to add substances. The purification efficiency of helophyte filters is high while the energy consumption is low, at the most the water has to be pumped up once to be properly distributed over the filter. The latter occurs in particular with vertically flow-through filters where the aeration takes place to a large extent through interruptions in the irrigation.
Practical applications
Helophyte filters are installed to filter, for example, ponds or run-off water from roads, but also to create ecological connection zones, create nature-friendly banks and frog pools.
Surface water in residential areas is also increasingly being treated in this environmentally friendly manner. This often gives the residents of these neighborhoods a good feeling, in a natural way clean water in the ditches. This increases the enjoyment of living.
Motorway drainage is often done in water collectors in the armpits of junctions. The so-called water basin is planted with purifying plants in order to naturally remove the pollutants here.
More and more companies want to contribute to corporate responsibility and filter their own wastewater by means of helophyte filters. Wastewater from production processes, as well as water from the sanitary facilities of offices, is increasingly being treated in this way.
What types of water plants are suitable for water purification
Most helophyte plants are grassy or reed-like, but there are also some with an elongated leaf. There are many varieties that bloom with beautiful flowers, but all have a strong root system with which they get a lot of nutrients from the water. Because of this function they are excellent to use to fulfill their function in the filter.
A number of types are extremely suitable for a helophyte filter:
- Iris pseudacorus
- Phragmites australis
- Sparganium erectum
- Acorus calamus
- Typha angustifolia
- Scirpus lacustris