INFORMATION ON PHYTODEPURATION AND EVAPOTRANSPIRATION SYSTEMS

The phytodepuration and evapotranspiration systems are a natural depuration treatment and they use the capacity of the plants to absorb the watery part of the sewage and to degrade a lot of organic substances. Such systems can be adapted as a secondary treatment of civil sewage of medium-small residential complexes or as a finishing tertiary treatment of industrial or civil waste of big amounts. The incoming sewage must be properly treated according to the typology of the existing polluting substances.

EVAPOTRANSPIRATION SYSTEMS: PRODUCTION COMPONENTS

The pre-treated sewage is put in the evapotranspiration compartment which is appropriately designed to transpire the sewage and eliminate the polluting substances quantity.
The evapotranspiration system consists of a basin made with materials in HDPE which are thermowelded on site.
The base is filled with a variable thickness according to the specific dimensions with draining materials, inside which the sewage distribution system is installed. Such system consists of microcracked pipes made of plastic materials. The surface layer consists of the autochthonous soil ideally selected during its construction. The size of the transpiring surface is made according to the organic and hydraulic load coming to the system. For a pre-treated civil sewage small surfaces equal to 4mq per inhabitant are usually considered.
On the surface various types of perennial herbaceous plants and shrubs are grown. These plants are ideally chosen among those which are mainly hygrophilous in order to find the right compromise between the aesthetic aspect and the functional aspect.
At the outlet there is a pit of variable sizes according to the incoming load and that of rain to install a timing pump to release, whenever necessary, water at the top of the plant.

Catch basin excavation
Geomembrane laying
Filling with vegetable soil
Plantation made

FUNCTIONALITY OF THE SYSTEM

This typology of system is based on the evapotranspiration principle, a phenomenon through which the vegetation absorbs water and organic substances from the soil transpiring the exceeding sewage, disguised as water vapour, through the leafy surfaces. This means that the outcoming load from the system is practically slight.
Moreover the organic substances in the sewage undergoes a degradation from aerobic bacterias and fungal that grow as rhizomes of the plants and anaerobic microorganisms of the deepest layers of the basin.

An evapotranspiration system has many advantages, among which the following ones are to be noted:

	a low or no energy consumption;
	absorption of the incoming sewage and removal of polluting wastes;
	easy installation in any type of environment;
	absence of smells and irritating noises.

The choice of the botanic species can vary within a wide range of possibilities, because we can use wild herbaceous species that can be found in the area of the system, or cultivated shrub species.
The first solution is adopted when it is necessary to set a system harmonious to the surrounding environment (for example naturalistic parks, oasis, etc…).
If the second solution is adopted we can create a real garden using various vegetation species of different height and growth. Some of them can be characterised by flourishing blooms. Moreover the shape of the basin of the evapotranspiration system can be shaped according to the needs and the size of the space. This possibility together with a lack of smells and noises makes this type of system an ideal choice in a urban context or near other build-up areas or production sites.