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Wastewater reuse was recognized as one of the solutions for the problems regarding increasing water scarcity and pollution of water resources. Constructed wetlands (CWs) are a sustainable and costeffective technology for wastewater treatment. If able to produce effluent of a needed quality, they can be a valuable addition for wastewater reuse schemes. This review studied 39 treatment systems based on CWs, and it assessed their characteristics and performance on pollutants removal. Moreover, their potential to reach the future European Union standards for agricultural wastewater reuse was evaluated. The results showed that the combination of CWs with additional techniques (e.g. UV treatment, anaerobic reactors) can further increase their performance and provide better removal efficiencies in comparison with conventional HSSF and VSSF CWs. Particularly, hybrid systems showed a better removal of organic matter and bacterial indicators than single-stage CWs. Most of the systems considered could reach some of the limits for agricultural reuse in the terms of biochemical oxygen demand and total suspended solids, although improved single-stage CWs and hybrid systems were able to meet stricter requirements. However, that was often not the case with Escherichia coli and therefore it is recommended to combine them with disinfection technologies in order to reach the levels required for agricultural reuse.

Agricultural drainage water that has seeped into tile drainage systems can cause nitrogen and phosphorus pollution of the surface water bodies. Constructed wetlands (CWs) can help mitigate the effects of agricultural non-point sources of pollution and remove different pollutants from tile drainage water. In this study, hydrological and water quality data of a Northern Italian CW that has been treating agricultural drainage water since 2000 were considered to assess its ability to mitigate nitrogen and phosphorus pollution. The effects of such long-term operation on the nutrients and heavy metals that eventually accumulate in CW plants and sediments were also analysed. Since 2003, the CW has received different inflows with different nutrient loads due to several operation modes. However, on average, the outflow load has been 50% lower than the inflow one; thus, it can be said that the system has proved itself to be a viable option for tile drainage water treatment. It was found that the concentration of nitrogen and phosphorus in the plant tissues varied, whereas the nitrogen content of the soil increased more than 2.5 times. Heavy metals were found accumulated in the plant root systems and uniformly distributed throughout a 60 cm soil profile at levels suitable for private and public green areas, according to the Italian law

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