Constructed Wetlands for tertiary treatment
Constructed wetlands are usually adopted as nature-based solutions for tertiary treatment of centralised activated sludge WWTPs, for instance, due to either an increase of served town or more stringer water quality standard for discharge. Particularly, constructed wetlands are used for tertiary treatments to either provide denitrification or guarantee the effluent wastewater quality standard under variable peak influent loads. They are also used to exploit additional ecosystem services, such biodiversity increase and recreation of areas with a high naturalistic value.
Advantages
- high treatment efficiencies in terms organic and nutrient loads
- high pathogen removal
- simple construction and functioning
- simple maintenance
- almost negligible OPEX in comparison to conventional systems (no or almost negligible energy consumption)
- landscaping
- neither odour issues, mosquito proliferations, nor aerosol
- no use of chemical compounds
- no need for specialised personnel
More information
Constructed wetland for tertiary treatment
Several application of constructed wetland for tertiary treatment are known worldwide. For instance, UK counts more than 200 applications in this field. The most representative Italian case is the tertiary treatment of Fusina WWTP: a free water surface system of 100 hectars, treating 4000 m3/h and fully integrated in the Venice lagoon. Another relevant Italian example is the tertiary stage of Jesi WWTP (60,000 PE), designed by IRIDRA: the system is composed by a sedimentation basin, an horizontal subsurface flow systems (10,000 m2) and a free water surface system (50,000 m2), aimed to improve the denitrification and the pathogen removal of the WWPT (Masi, 2008).
Tertiary constructed wetland of the Jesi WWTP (60.000 AE), designed by IRIDRA
References
IRIDRA's authors are highlighted in bold.
Masi F., (2008) “Enhanced denitrification by an hybrid HF-FWS CW in large scale wastewater treatment plant (Jesi)” , in “Wastewater Treatment, Plant Dynamics and Management in Constructed and Natural Wetlands”, by Jan Vymazal (Ed.), Springer, NY, ISBN: 978-1-4020-8234-4, pp. 267-275.