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Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«. 49 3 Experiences in Italy In Italy the floating wetland system was applied in 2005 for the first time to treat water outflow from a fish farm. Since then, several experiments were carried out with the purpose to study the most suitable vegetation to be used and the performance of floating barriers for FTW purposes. 3.1 The vegetation The vegetation fulfils multiple functions in wetland systems; the attention has to be drawn on aquatic plants with well-developed root system, with not too tall aerial parts to avoid the risk of reversal of the barrier do to wind gusts. If the barriers or islands are installed with aesthetic purposes it becomes interesting to consider the flower characteristics (colour, size, duration of inflorescence), the phenology (with particular attention to time and duration of flowering), and other potentially interesting features, such as shape, colour and duration of leaves, perfume emissions etc. The most interesting plants are:
bloom in early spring, from May to June. It reproduces from rhizome, has leaves that branch from the base of the plant and are large up to 3 cm. Every year plants release new shoots from the rhizomes. It grows in mid or full sun close to water but also submerged till about 15 cm, within a wide range of pH-values, from acid to alkaline; it is very strong, can resist to flood and dry periods too. Iris is often used in constructed wetlands for its capacity of pollution removal and in FTWs too (Van de Moortel , 2011).
Figure 3: Iris pseudacorus L.
Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«. 50 Iris laevigata Fisch. This species originates from East Asia and is cultivated especially in Japan. Its name is due to its petals that are rotund, short and vertical. This Iris needs humid soil all over the year and does not tolerate dryness; it prefers acid or neutral pH and loves to leave in water till 15 cm depth. It reaches more than 90 cm in height and can be up to 30 cm in width, depending in which climate it grows, even if it prefers temperate one. Flowers are about 7 to 10 cm long, and bloom in summer; they can be white, blue or red-purple. Canna indica L. Cultivated as ornamental plant, it can reach the height between 150 and 250 cm. The leaves and the flowers are very decorative and different varieties that bloom during summer can have different colours with lots of shades. This species loves sun but can tolerate shadow too. In winter above ground vegetation disappears but rhizomes stay alive below ground, to grow in spring again. It is sensitive to cold winters.
Figure 4: Canna indica L. Juncus effusus 'spiralis' L. This aquatic macrophyte, typical of wetlands, has smooth, lucid and bright green stem that twist from the base of the plant. Its green-brown inflorescence appears in summer. It can be up to 90 cm high and 60 cm wide. It grows in humid or swampy soil, and also in shallow water, it is excellent for aquatic garden. This species has been widely used in FTWs (Van de Moortel, 2011; Hubbard et al., 2004).
Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«. 51 Mentha aquatica L. (Figure 5) belongs to the family of Labiatae, which includes many of species often used in perfumery and medicine thanks to their production of essential oil composed mainly of menthol. Flowers of this herbaceous species are pink-purple and appear in summer; it can reach 80 cm in height, even if its aerial part is creeping. Its woody rhizomes produce aboveground creeping stolons. It is typical of wetlands, such as riverside, on bogs or swamps. It thrives in shadow and humid environments, from the sea to the mountains. Pontederia cordata L. (Figure 6) belongs to Pontederiaceae and is native from North America. Its leaves are lucid and heart shaped, and its big decorative flowers can be white, blue, pink or lavender and bloom in summer. This plant is often used as water filter (McConnel et al., 1990). Normally these plants propagate by division of rhizomes in spring but they can also been seeded even if they need a period of dormancy with cold and humid conditions. To survive at cold temperatures is important that young plants originate from cultivars that were grown in cold climate (Kane et al, 1991). It can grow in full sun or middle shadow in humid soil or in water till 25 cm depth. It reaches 60-75 cm in height (Speichert and Speichert, 2004). In addition to this list the well-known, and widely used Typha latifolia L., and Phragmites
2010; 2011; 2012; Mietto et al., 2013).
Figure 5: Mentha aquatica L. Figure 6: Pontederia cordata L.
Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«. 52
Installations Different installations have been realised in Italy, the prevalence of them in peri-urban basins downstream of wastewater treatment plants with the main goal of tertiary treatment. In some cases Tech-IA barriers have been directly installed in streams, channels, and in accumulation basins. Projects have been also presented to Municipalities with the purpose to enhance the aesthetic value of channels in urban environment. The designs of the systems were always different site to site (Figure 7), according to local needs and conditions. The installation was easily managed, as well as the maintenance operations. The vegetation was able to colonise the mats and develop root systems reaching 40-50 cm of depth at the end of the first growing season. The performance in ameliorating water quality has been different in relation to the pollutant type, the concentrations upstream the barriers, and the residence time. Reduction of pollutants reaching up to 70% for total nitrogen, 49% for ammonia-N and 67% for nitrate, 30% for phosphorus forms, and 60% for COD have been measured (De Stefani et al., 2012). Tech-IA floating installations also contributed new sites for wildlife, since many nests of aquatic birds were found in the vegetation and fishes used the root system as refuge and sites to attach their eggs.
Tech-IA floating system proved to be a very simple and flexible tool to build vegetated barriers or islands in different types of water bodies. The installation is very easy and the design can also be modified during the time according to new needs and perspectives. The adequate choice of vegetation can enhance the value of the installation, offering an interesting aesthetic value. Multiple possibilities of use can be considered in urban environments: in internal channels, in lakes or pools inside parks and green areas, in basins collecting and treating runoff water, as FTW downstream of wastewater treatment plants and in many other sites where the objective is the amelioration of water together with the enhancement of the environmental quality.
Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«. 53
Figure 7: Some examples of Tech-IA installation schemes in Italy 5 Bibliography and sources Billore S.K. and Prashant S.J.K.. Restoration and conservation of stagnant water bodies by gravel- bed treatment wetlands and artificial floating reed bed in tropical India. Proc. of 11th International
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Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«. 54 Boutwell, J.E. Water quality and plant growth evaluations of the floating islands in Las Vegas Bay, Lake Mead, Nevada, 2002. U.S, Department of the Interior, Bureau of Reclamation, Denver, Colorado, pp. 24. De Stefani G., Mietto A., Salvato M., Borin M. Performance of a combined wetland (h-SSW and FTW) in treating municipal wastewater in Veneto Region (Italy). Proc. 13th International Conference on Wetland Systems for Water Pollution Control, 2012, Perth, Australia De Stefani G., Tocchetto D. and Borin M. Performance of a floating system as tertiary treatment for urban wastewater. Proc. of 12th IWA Int. Conference on Wetland systems for water pollution
De Stefani G., Tocchetto D., Salvato M. and Borin M. Performance of a floating treatment wetland for in-stream water amelioration in NE Italy. Hydrobiologia, 2011, 674, 1, 157-167 Hart B., Cody, R., Truong P. Hydroponic vetiver treatment of post septic tank effluent. Proc. Third International Conference on Vetiver, 2003, Guangzhou, China. Hubbard R.K., Gascho G.J. & Newton G.L. Use of floating vegetation to remove nutrients from swine lagoon wastewater. Transactions of the ASAE, 2004, 47:1963-1972. Kyambadde J., Kansiime F. and Dalhammar G. Nitrogen and phosphorus removal in substrate- free pilot constructed wetland with horizontal surface flow in Uganda. Water, Air, and Soil
Ladislas S., Garente C., Chazarene F., Andrea Y. and Brisson J. Performances of floating treatment wetlands to remove cadmium, nickel and zinc from urban stormwater runoff. Proc. 12th
McConnel D.B., Kane M.E. and Shiralipour A. Growth of pickerelweed in municipal solid waste compost and yard trash compost. Proc. Fla. State Hort. Soc., 2010, 103: 165-167. Mietto A., Borin M., Salvato M., Ronco P., Tadiello N. TECH-IA floating system introduced in urban wastewater treatment plants in Veneto Region – Italy. Water Sci. and Techn., 2013, 68.5, 1144-1150 Revitt D.M., Worrall P., Brewer D.. The integration of constructed wetlands into a treatment system for airport runoff. Water Sci. and Techn, 2001, 44: 469-476. Smith M.P., Kalin M. Floating wetland vegetation covers for suspended solids removal. Treatment wetlands for water quality improvement. Proceeding of Quebec 2000 Conference, CH2MHILL, Canada. Stewart, F.M., Mulholland, T., Cunningham, A.B., Kania, B.G., Osterlund, M.T. Floating islands as an alternative to constructed wetlands for treatment of excess nutrients from agricultural and
Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«. 55 municipal wastes - results of laboratory-scale tests. Land Contamination & Reclamation, 2008, 16: 25–33. Tanner C.C., Headley T.R. Components of floating emergent macrophyte treatment wetlands influencing removal of stormwater pollutants. Ecological engineering, 2011, 37: 474-486. Van Acker J, Buts L., Thoeye C., De Gueldre G. Floating plant beds: BAT for CSO treatment? Book of abstracts from international symposium on wetland pollutant dynamics and control, September 4-8, 2005, Ghent Belgium: 186-187. Van de Moortel, A.M.K. Constructed floating wetlands for combined sewer overflow water treatment. PhD thesis, faculty of bioscience Engineering, 2011, Ghent University, Ghent, Belgium. 244 p.
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