Floating treatment wetlands for P and N removal from runoff effluents.

MUFARREGE, M. M.; DI LUCA, G. A.; DE LA PEÑA, R.J.; JIMENEZ CATTALIN, M.J.; CARRERAS, A.A.; HADAD H.R.; MAINE, M.A.

Valencia

Conferencia; ?16th IWA International Conference on Wetlands Systems for Water Pollution Control?; 2018

The aim of this work was evaluated the P and N removal of synthetic runoff effluent using microcosm-scale floating treatment wetlands (FTW). Plants of Typha domingensis, sediment and water were collected from an unpolluted pond near Santa Fe city, Argentina. The plants were pruned for their transport to the greenhouse. Plastic reactors (70 L) contained 4 Kg of sediment and 40 l of water were disposed outdoors under a semi-transparent plastic roof. In six reactors, FTWs were disposed, 3 were exposed to a synthetic effluent (reactors A), and 3 were used as biological controls (CB: without addition of the effluent). Each FTW consist in a plastic net and had a surface area of 0.10 m2. Buoyancy was provided by a PVC frame (diameter: 12.7 mm). Each raft had a total of 4 plants. The rafts were designed to allow roots (hanging in the water column) and rhizomes remain in the water while aerial parts emerge. Thereby, macrophyte asexual reproduction was permitted. There were also six reactors without FTWs, 3 were exposed to synthetic effluent (reactor B: only sediment) and 3 were used as chemical controls (CC: with sediment and without effluent addition). After acclimatization of the plants, 38 L of the synthetic effluent containing 10 mg L-1 N + 2 mg L-1 P was added in the reactors as follow: 3 reactors with FTW (A: with FTW and contaminant addition); 3 reactors without FTW (B: without FTW, with contaminant addition); 3 reactors Biological Controls (BC: with FTW, without contaminant addition) and 3 reactors Chemical Control (CC: without WTF nor contaminant addition). During the experiment, three synthetic effluent dumps were made. The experiment lasted 70days. Conductivity, DO, pH, SRP, TP, N-NH4+ and N-NO3- were efficiently removed from water during the experiment. The percentages of removal of PRS and PT were significantly higher in the reactors A than the reactors B. N-NH4+, were not significantly differences between reactors A and B, while N-NO3- was efficiently removal from water in the reactors A than in the reactors B. At the end of the experiment, the chlorophyll concentration, the aerial and submerged (roots and rhizomes) biomass increased significantly in the reactors A. No significant differences were observed in the PT concentrations between rhizomes and leaves, while in the roots the lowest concentrations were observed. The TKN in tissues was significantly higher in roots and rhizomes than in aerial parts. The concentrations of PT and TKN in the sediment did not show differences between the different reactors throughout the experiment. The results show that the use of WTF is a promising strategy for the sustainable treatment of bodies of water affected by urban runoff.