Online measurements
Constructed wetland pilot plant The experiment was carried out in an intermediate-scale pilot plant, 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 a geotextile layer and high-density polyethylene (HDPE) to make the CW impermeable. A slope of 1% was required in the plot to maintain the hydraulic gradient of the beds. The inlet zone consisted of apipe with 2 L h−1 emitters to regulate the flow (0.24 m3day−1) perexperimental line. Two online instruments tomonitor the CW were connected to one of the six available beds of the pilot plant at the inflow and outflow pipes