Performance of a full scale constructed wetland as ecological practice for agricultural drainage water treatment in Northern Italy

Abstract

Non-point sources of pollution, primarily agricultural drainage waters, can cause eutrophication and deterioration of water bodies. Surface flow constructed wetlands (SFCWs) are an ecological solution that can represent an efficient barrier and prevent agricultural pollutants from reaching other ecosystems. However, to better manage them and to understand removal processes occurring, it is important to study SFCWs that are functioning for longer periods of time and assess their efficiencies. This study concentrates on a full-scale SFCW in the Northern Italy that has been treating agricultural drainage water for past 20 years. An in-deep monitoring done for two years (2018 and 2019) showed that the system achieved satisfactory retention of up to 82% for TSS and up to 78% for TN and NO3 --N. TP retention seemed to be poor, but further analysis showed that the SFCW performed well in this aspect as well, and that it is important to include precipitation loads in the overall balance. Soil content of nutrients and different trace elements did not show considerable differences in respect to the beginning of the monitoring period, and the uptake rates of TN and TP by above-ground vegetation were in the range 19.0-26.3 and 1.6-2.1 g m -2 , respectively.

Mechanistic understanding of the pollutant removal and transformation processes in the constructed wetland system

“…For instance, Tanner (1996) conducted a study using eight emergent macrophyte species ( Cyperus involucratus , Phragmites australis, Choenoplectus validus, Glyceria maxima , Baumea articulata , Juncus effuses , Bolboschoenus fluviatilis , and Zizania latifolia ) and found that nitrogen uptake in the above‐ground tissues of the species ranged from 15 to 32 mg/g was 65–92% of total nitrogen removed in CWs. Recently, similar findings were reported by Lavrnić et al (2020) in Italy. In SFCW, Lavrnić et al (2020) observed that the total nitrogen uptake range from 19 to 26.3 g/m 2 was 46–70% of total inflow nitrogen in CWs.…”

“…Koottatep and Polprasert (1997) reported that plants in CWs can effectively remove 66%–71% of total nitrogen through plant uptake. Globally, several studies have reported the nitrogen removal that occurred through uptake and assimilation in CWs (Gottschall et al, 2007, Jampeetong et al, 2012, Lavrnić et al, 2020, Maltais‐Landry et al, 2009, Nandakumar et al, 2019, Nilsson et al, 2020, Nitrogen & Wetlands, n.d.; Pincam et al, 2020, Tao, 2018, Vymazal, 2007, Vymazal & Kro, 2009, Zhang et al, 2016). In some studies, a positive correlation between the plant biomass and N uptake was observed.…”

Constructed Wetlands to Face Water Scarcity and Water Pollution Risks: Learning from Farmers’ Perception in Alicante, Spain

“…As transition zones between terrestrial and aquatic environments [39], CWs are perceived as a cost-effective (low-cost and straightforward construction, operation and maintenance reduced costs, or energy biomass production) [40] and ecological and sustainable technology for treating different types of wastewater without the input of fossil fuels [41]. Likewise, CWs can contribute to flooding risk mitigation, stormwater runoff management, and increase water supply [42] by constituting an alternative option to conventional wastewater treatment plants (WWTPs) [43].…”

New developments in biological phosphorus accessibility and recovery approaches from soil and waste streams

“…Full‐scale application of the floating wetlands is reported by Lavrnic et al. (2020) [42] but with inconsistent P removal efficiency due to the rain precipitation effect. A subsequent P‐recovery from biomass is a valid option.…”