Pharmaceuticals removal in a H-SSF treating a secondary domestic wastewater – an experimental investigation

In these last decades, an increasing attention has been paid to the monitoring of Pharmaceutical compounds in wastewater treatment processes, in order to evaluate the removal capacities of the different stages with respect to the most important compounds. In force regulations in the different countries as well as European directives take in consideration many “new” substances (including pesticides, flame retardants) and set concentration limits for the discharge into surface water body. But pharmaceutical compounds are not included among them. The last European Parliament draft, amending Directive 2000/60/EC labels only few compounds as priority substances: carbamazepine, diclofenac, iopamidol, without setting limits. Constructed wetlands have a well-known buffering capacity in removing many macro- and micro-pollutants (mainly pesticides and heavy metals). Only few studies have investigated their behavior in removing pharmaceuticals. In this context, an experimental campaign has been conducted on a horizontal subsurface flow system, treating the secondary effluent of the wastewater treatment plant of the town of Ferrara (Northern Italy) in order to assess the removal rates for the different therapeutic classes of pharmaceuticals (analgesics, antibiotics, betablockers, diuretics,...) and for the most important compounds (among them ciprofloxacine, sulphametoxazole, carbamazepine, diclofenac). The investigated bed is vegetated, filled with gravel (8-10 mm), it has an area of 28 m2 (28 x 1) and an average water depth of 1.2 m, the influent flow rate is constant and equal to 8 m3 d-1. Specific removal rates have been correlated to the corresponding chemical characteristics of the compounds (in particular Log Kow, kbiol) and compared to literaure data. Moreover, chemical and physical characteristics (redox potential, conductivity, pH, T) of the horizontal bed has been investigated at different depths and distances from the inlet by means of water samples withdrawn through probes