Joint International Conference on Long-term Experiments ...

The advantages of this technology are numerous:
• These are ecological and natural systems, and they can represent a habitat for
other species that do not take part in the purification process (plants, birds and
other animals);
• The system doesn’t need too much maintenance work, big stuff (numerous
employees), and compared to the classic technology it has low operating costs;
• It is not as expensive to be built as the classic systems;
• Constructed wetlands can reach the same high efficiency than the classic
systems;
• They can be used as a zone of recreation, of entertainment, sport and other
events for people;
• Corrects the panorama of the region.
General aspects regarding the plants that can be used in the purification process
The world’s flora is divided in more floral zones that are organized in systems and
subsystems, on each continent. Valea Ierului (Érmellék)’s aquatic flora belongs to a
temperate climatic zone and it is characterized by a vegetation period in winter time. In
this period, when the water loses its flowing capacity because it freezes, the life
processes of the plants are going to slow down. After that some enzymatic processes
start to take place and the result is the development of the vegetative organs.
There are more types of constructed wetlands taking into consideration the plants
that are going to be used: wetlands with emergent, submersed and floating plants; they
can also use the both types of plants. The natural growth is influenced by many factors
as: the water’s depth, the extension of the water surface, debit and change of the water
level. As some secondary factors we can mention the atmospheric factors (temperature,
precipitation, wind speed, evaporation, number of hours with sunlight, etc.), pedological
factors (type of the soil, clay quantity, etc.), biological factors (the presence of certain
floral and fauna species) and characters of the bulked wastewater (qualitative and
quantitative composition, ph, temperature, turbidity, content of the organic material).
These factors are going to be researched in the next period of our scientific activity.
The emergent plants are the most frequent plants in the aquatic systems. They can
be found in the marshes and bogs, where the plants are fixed in the sediments with their
roots, having their stems and leaves above the water surface. In the water they create
some biological associations, named biofilters, and in that way they contribute to the
cleaning process. Such plants are the common reed (Phragmatis australis, Phragmatis
comunis), the rush (Schoenoplectus lacustris ) and the bulrushes (Typha latifolia, T.
augustipfolia, T. minima).
Other types of the macropytes are the floating plants, which – due to their special
cellular constitution and their air filled leaves – are drifting on the water surface. They
have two subcategories, some of them being unattached and others attached floating
plants.
The floating unattached plants are drifting on the water surface without touching
the bottom with their 20-30 cm long roots. The Pistia Stratiotes or the Eichornia
Crassipes belong to this category. The floating attached plants are also floating on the
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