Constructed wetlands FITOBOX

DESIGN AND CONSTRUCTION

Designing a reedbed system is not simple
TRUE
Being a natural treatment, reedbeds do not fall within the framework of the exact sciences and the various equations include factors of uncertainty that the designer must carefully evaluate. For this reason it is important to contact a company with great experience.

Reedbeds are not very deep.
TRUE
Since the roots of the plants used do not reach depths greater than 80 cm, reedbeds have a maximum depth of about 80-100 m. Reedbeds with higher depths are unnecessary and counterproductive as part of the waste water escapes the action of the plants.

One of the limits of reedbeds and constructed wetlands is the need for dedicated surface
TRUE
Constructed wetlands needs more usable area than conventional systems, not always available to those who would like to apply it.

Making a reedbed is easy
FALSE
The lack of advanced technology suggests that it is relatively easy to build a reedbed, but in reality there are several technical solutions to follow, unknown to most people, which makes it necessary to rely on a tried and tested product.

Reedbeds are filled with soil
FALSE
Soil must never be used for filling reedbeds. It damages the plant impairing its functionality since it causes the growth of weeds and probably the clogging of the entire system. Aquatic plants have to live only on what they find in the wastewater and they don't have to draw nourishment from chemical and biological elements of the soil.

Reedbeds are divided into two categories: horizontal subsurface flow and vertical subsurface flow.
TRUE
The most common of all are the horizontal subsurface flow reedbeds (maximum depth 0.8 m), easier to realize and easier to manage. The vertical flow ones (maximum depth 1.1 m) need smaller surface but require a discontinuous supply of wastewater only possible with equalization tanks and pump station that increase operating costs.

The plants suitable for reedbeds belong to a few selected species
TRUE
For reedbeds can be used Phragmites Australis, several varieties of Typha, Juncus, Carex, Scirpus and Iris Pseudacorus.

USE AND OPERATION

Reedbeds are not suitable for seasonal use
FALSE
Nothing could be more false! Reedbeds are precisely the most suitable system to treat wastewater from seasonal users, such as farms, campings, hotels, country houses, etc.. Unlike conventional activated sludge systems, reedbeds do not suffer variations in organic load being able to have much higher hydraulic residence times. This makes them particularly effective in the treatment of wastewater of seasonal activities such as wineries.

Reedbeds and constructed wetlands are suitable for re-use of wastewater
TRUE
Constructed wetlands, if well sized, allow reuse for irrigation of wastewater, with obvious advantages of energy saving and re-use of the resource.

Constructed wetlands allows the high reduction of the bacterial load
TRUE
It has been proved that reedbeds reduce 99% of the bacteria present in the wastewater, with peaks of 99.9%. In fact, the alternation of aerobic and anaerobic conditions in the aggregates that fill the system does not allow the survival of the vast majority of bacteria in the wastewater treated.

Reedbeds generate odors and allows the proliferation of annoying insects such as mosquitoes
FALSE
In subsurface flow systems the level of the wastewater is maintained at a minimum depth of 10-15 cm from the surface: the surface of the reedbed is then dry. This prevents bad odors and the deposit of insect larvae (problems may occur in systems with surface flow, pond type, not dealt with here).

MANAGEMENT AND MAINTENANCE

After a few years the acquatic plants need to be replaced
FALSE
In reedbeds, if properly dimensioned, you do not need to replace the aquatic plants.

Reedbeds require periodic emptying of septic tanks
TRUE
As with the other treatment systems, for the proper functioning through time of a reed bed, septic tanks must be emptied periodically (the frequency depends on the volume of the septic tank).

Some plants can be cut in the winter period
TRUE
In cold weather the plants used in the majority of cases (Typha and Phragmites Australis) acquire that "dry" aspect of that some may not like. These plants can be cut even up to a few centimeters in height. This does not reduce the exchange of oxygen in the rhizosphere (roots-substrate) which allows the treatment of the wastewater.

COSTS

The costs of management and maintenance of reedbeds are almost zero or insignificant
TRUE
Except for the periodic emptying of the pre-treatment, however required for all treatment systems, constructed wetlands and reedbeds does not have significant management costs, as devoid of electromechanical parts (and therefore it is not even necessary skilled labor). Only for vertical subsurface flow reedbeds, for which it is necessary a discontinuous flow of the wastewater, there are costs associated with the use of pumps. For this reason, if possible, for small plants it is recommended the use of horizontal subsurface flow systems, in which there is no need for electricity and complex technologies.

DURABILITY

Good constructed wetlands are made to last
TRUE
A constructed wetland, if well designed and well managed, can last more than 25 years.

If poorly managed a reedbed can become clogged
TRUE
If the pre-treatments are not emptied periodically, the plant slowly becomes clogged, thus invalidating the operation of a plant also well built. Nevertheless, in most cases, appropriate measures taken during construction can make simple the possible intervention of maintenance needed for resetting the system.