Grey water treated by an hybrid constructed wetland pilot plant under several stress conditions

The aim of the present study was to design, realize and analyze a functional hybrid phytoremediation pilot platform. To realize the experimental platform, the most known advanced solutions were used and analyzed. The pilot plant was tested with and without vegetation at the design specifications. Than different organic and hydraulic load of grey water were performed. The COD, electrical conductivity (EC), pH and total dissolved solids (TDS) were analyzed in the different treatment stages of the system. Our purpose was to evaluate the feasibility and the treatment efficiency under variable and stress conditions. The results of the tests conducted with an inlet flow ten times higher than design ones (500 L/d) has shown that the pilot plant is able to work until contaminants elements are three times higher of the design quantity. When the tests with vegetation presence were started inside the pilot plant, the obtained results were always positive (in terms of COD reduction). Using design inlet flow of 50 L/d with two times and four times higher GW pollutant quantity, the COD values drop to zero after the initial stage (that has a retention time measurable in minutes). The planted system is able to handle the COD reduction of an OLR that at the beginning of the treatment stage had a value of about 31 gCOD/m2/d, equal to a triple charge of pollutants, and a flow four times greater than the design one with triple charge of pollutants and conducting the tests at increasing inlet flow. The pilot plant process the inlet grey water in about 24hr. This time represents a quarter of the design time.