Response of Typha domingensis Pers. in floating wetlands systems for the treatment of water polluted with phosphorus and nitrogen.

The aims of this work were to evaluate the effects of P and N on the tolerance and root morphometry of Typha domingensis plants, and their implication in removal efficiency in floating treatment wetlands (FTWs). Pilot-scale plastic reactors containing plants, sediment, and tap water were arranged. FTWs consist of a plastic net, and buoyancy was provided by a PVC frame. After plant acclimation, 38 L of the synthetic effluent containing 10 mg L-1 N + 2 mg L-1 P was added to the reactors as follows: reactor A (with FTWs), reactor B (without FTWs), reactor BC (biological controls), and reactor CC (chemical control). Reactors were arranged in triplicate. During the experiment, three effluent dumps were made. The removals of SRP and TP were significantly higher in reactor A than in reactor B. N-NH4+ removal was not significantly different between reactors A and B, while N-NO3- removal from water was higher in reactor A than in reactor B. At the end of the experiment, chlorophyll concentration and aerial and submerged (roots and rhizomes) biomass increased significantly in reactor A. TP concentrations were not different between rhizomes and leaves, while the lowest concentrations were observed in roots. The TKN in tissues was significantly higher in roots and rhizomes than in aerial parts. In plants exposed to the experimental solution, the internal and external root morphology changed. The use of FTWs is a promising strategy for the sustainable treatment of nutrient polluted water bodies.

Vertical flow wetlands and hybrid systems for the treatment of landfill leachate.

Landfill leachates contain a variety of toxic compounds, which makes them one of the most difficult types of wastewater to be treated. An alternative "green" technology for leachate treatment is the use of constructed wetlands (CWs). The aims of this study were to select macrophytes and substrates to be used in vertical flow wetlands (VFWs) and to evaluate the performance of hybrid systems composed by a VFW and a horizontal subsurface flow (HSSW) or a free water surface flow (FWSW) wetlands for the treatment of a high ammonium concentration landfill leachate. In microcosms scale experiments, Typha domingensis, Scirpus californicus, and Iris pseudacorus were studied to assess their tolerance to raw and diluted leachate. Substrate selection for VFWs was evaluated using different layers of light expanded clay aggregate (LECA), coarse sand, fine sand, and gravel. Contaminant removals were higher in planted than in unplanted wetlands. Plants did not tolerate the raw effluent but showed a positive effect on plant growth when exposed to the diluted leachate. T. domingensis and I. pseudacorus showed higher contaminant removal ability and tolerance to landfill leachate than S. californicus. VFW with LECA + coarse sand showed the best performance in removal efficiencies. Hybrid system composed by VFW-FWSW planted with T. domingensis presented the best performance for the treatment of landfill leachate with high concentrations of ammonium.

Long-term study of Cr, Ni, Zn, and P distribution in Typha domingensis growing in a constructed wetland.

The aim of this work was to study Cr, Ni, Zn, and P bioaccumulation in different compartments of Typha domingensis plants and sediment in a free-water surface constructed wetland for the treatment of a metallurgical effluent for 5 years. Removal efficiencies were satisfactory. To increase metal tolerance, its transport from belowground to aboveground tissues is reduced, being metal concentrations in the roots and rhizomes significantly higher than in the aerial and submerged parts of leaves. Regarding belowground tissues, metals were retained in the roots, while P was mainly accumulated in rhizomes. Bioaccumulation factors (BAFs) of Cr and Ni showed values near 1, and BAF of Zn and P were above 1 in several samplings, indicating bioaccumulation in the roots. Translocation factors (TFs) of Cr, Ni, and Zn were below 1, showing a scarce translocation from the roots to the aerial parts of the leaves, while the TF of P were above 1 in many samplings, indicating that this element is necessary for plant metabolism. The study of plant tissues where contaminants are accumulated allows gaining insight into the constructed wetland operation. The high translocation of P in T. domingensis makes this species suitable for its phytoextraction, while the low metal translocation makes T. domingensis suitable for phytostabilization.

Macrophytes as potential biomonitors in peri-urban wetlands of the Middle Parana River (Argentina).

The aims of this study were to measure the concentrations of nutrients and pollutants in peri-urban wetlands, to analyze the plant morphology of the most representative macrophyte species, and to determine their potential use as biomonitors. Four wetlands in the Middle Paraná River floodplain evidencing contamination or anthropogenic impact were studied. The studied species were Typha domingensis Pers., Eichhornia crassipes (Mart.) Solms., Alternanthera philoxeroides (Mart.) Griseb., and Pistia stratiotes L. Besides, the same plant species from an uncontaminated wetland considered as control were studied. A. philoxeroides showed the highest total phosphorus (TP) concentration in leaves throughout the study, while the other species showed a higher TP concentration in roots than in leaves. Since metal concentration in A. philoxeroides tissues was always higher than in sediment, further studies focused on its phytoremediation capacity should be carried out. T. domingensis exhibited the highest Zn concentrations in roots followed by Pb, and E. crassipes presented the highest values of Pb concentrations in roots. The aerial part height of the plants from peri-urban wetlands was significantly higher than that of the plants from the control, while the root length was significantly lower. The root length of P. stratiotes showed a negative correlation with soluble reactive phosphorus (SRP) concentration in water. All the root anatomical parameters of T. domingensis and E. crassipes showed a positive correlation with nitrate and ammonium concentrations in water. The studied macrophytes evidenced a high tolerance, enabling them to grow and survive in peri-urban wetlands that receive pollution from different sources. The use of aquatic and wetland plants as contaminant bioindicators and bioaccumulators in the Middle Paraná River floodplain is completely feasible.