Serial Use of Helosciadum nodiflorum and Typha latifolia in Mediterranean Constructed Wetlands to Naturalize Effluents of Wastewater Treatment Plants

Abstract

Constructed wetlands are commonly used for sewage treatment. However, as the natural processes operate, these artificial ecosystems can also be used to enhance the equalization of water features to those of the receiving environments, thus reducing the impacts of the treated water on the natural systems. Here, we studied, by a year-round survey, the simultaneous and separated operation of two subsurface wetlands that were used as a tertiary treatment to enhance the naturalization of wastewaters that had already been treated in a waste water treatment plant (WWTP). These wetlands were operating serially, with the first wetland being covered by the riparian plant Helosciadum nodiflorum, which has not been described so far as being used in treatment wetland, whereas the second was covered by Typha latifolia. The changes in the concentrations and transformation among the different types of pollutants and other physical and chemical parameters, as well as in the bacterial abundance and activity, were studied under different operational conditions of serial cooperation or of separately-operating wetlands. Both wetlands were differentially efficient in the reduction and transformation of the remaining pollutants, with very active nitrification and denitrification processes, which reduced the ammonium concentrations by more than 65%, although they changed according to the operational status of each wetland. They also reduced the already low organic matter contents by around 30% and promoted slight shifts in the dominant types of dissolved organic matter to less labile compounds. To a certain extent, the Typha-covered wetland also contributed to phosphorus removal, by up to 35%. Noticeably, both of the wetlands contributed greatly to the reduction of bacterial abundance, which was even 50% lower after the wetland transit, although the resulting community increased its activity, thus keeping the capacity for pollutant removal and transformation. Overall, the wetlands' operation increased the similarity between the poured waters and those of the receiving stream, thus diminishing its environmental impact.

Estimation of Water Coverage in Permanent and Temporary Shallow Lakes and Wetlands by Combining Remote Sensing Techniques and Genetic Programming: Application to the Mediterranean Basin of the Iberian Peninsula

“…Mapping flooded areas is essential, since wetland biodiversity reacts to flooding regimes [49][50][51], both in terms of water cover area and hydrological cycles. Wetland's biogeochemistry, including the carbon cycle and their exchanges of greenhouse gases (GHG) with the atmosphere, are also intimately linked to the water regime [52,53].…”

“…Note that a revisit frequency of five days might not be sufficient to capture the water changes in extremely dynamic water bodies, but it can fairly accomplish the monitoring requirements for the majority of lakes/wetlands types, even those temporary, in the Mediterranean Basin of the Iberian Peninsula. This might strengthen management strategy-linked lake conservation, and help to accomplish the goals of both the European Water Framework Directive (2000/60/EC) and the Habitats Directive(92/43/EEC), but also could be useful for the improvement of its role as carbon sinks under a climate change scenario [52,53] where the role of flooding, as well as that of macrophytes [49][50][51], would be of great relevance.…”

Assessment of the Pressure Level over Lentic Waterbodies through the Estimation of Land Uses in the Catchment and Hydro-Morphological Alterations: The LUPLES Method

“…To define the pressure levels, in the case of abstractions and transferences, the volumes extracted or transferred are compared to the maximum volume of the waterbody (Equations (6) and (7)). For heightening, the height of the over damming is compared with the maximum depth, as indicated in Equation (8). Data for these direct alterations at the studied sites were obtained for the sites listed in Table S1, with information gathered from the Spanish inventory DATAGUA [37].…”

“…Organic matter, nutrients, sediments or specific pollutants can reach the waterbodies by runoff and diffuse sources [5]. In fact, constructed wetlands are used to retain or detoxify pesticides and other pollutants, and are used as water filters [6][7][8]. Therefore, any activity or change produced in the catchment may have direct effects on the waterbody [9,10].…”