Constructed wetlands: a natural technique for treating civil wastewater with respect to environment and landscape

In Italy , the law n. 152 of 1999 fixed that every Municipality and urban settlement has to be equipped with a wastewater treatment system. Utilization of traditional depuration systems (total oxidation, bio-disks, etc) also for little settlements has never produced real benefits in term of pollutant removal; this because the hydraulic and organic load variations typical of little and medium settlements and touristic centres don't fit well with traditional technologies, but also because the technologic management of those plants is not sustainable for a little municipality, both economically and professionally.

The solution chosen for several years has been the construction of big treatment plants where convoy and treat wastewater of many settlement: but, considered the characteristics of our land, this solution brings to the necessity of realizing long and not cheap pipes. Moreover, the logic of centralization of the depuration treatment strongly alters the balances of water resource, damaging superficial and underground water bodies: in fact, it can happen that the great quantities of water captured for human necessities are given back to watersheds completely different from the withdrawal one, or to the same watershed but strongly downstream, creating the impoverishment of long fluvial drafts.

Constructed wetlands are a modern technology that uses the depurative capacity of natural ecosystems for human activities needs. Its application to wastewater of municipalities and settlements with 500 to 5000 P.E. has given very good results, with management costs 5-6 times lower than those of traditional plants, allowing an on-site wastewater treatment in a decentralized logic of the depuration system. More, it has to be considered the better environmental impact and the greater feasibility of constructed wetlands compared to traditional plants, quality that permits to consider the depuration plant not as something to confine away from urban areas, but as an instrument or environmental restoration.