Online measurements
Constructed wetland pilot plantThe experiment was carried out in an intermediate-scale pilotplant, comprising six horizontal subsurface flow CW (HSSCW)made of concrete, constructed in a covered outdoor plot at IRTAin Cabrils (Spain) (41◦25N, 2◦23E). All beds were covered with ageotextile layer and high-density polyethylene (HDPE) to make theCW impermeable. A slope of 1% was required in the plot to main-tain the hydraulic gradient of the beds. The inlet zone consisted of apipe with 2 L h−1emitters to regulate the flow (0.24 m3day−1) perexperimental line (Narváez et al., 2011). Two online instruments tomonitor the CW were connected to one of the six available beds ofthe pilot plant at the inflow and outflow pipes