Changes of a Landfill Leachate Toxicity as a Result of Treatment With Phragmites australis and Ceratophyllum demersum–A Case Study

Most phytoremediation studies are limited to several of the most common plants and in most cases these studies are performed to a very limited extent. There are also few publications on the assessment of the effectiveness of the removal of pollutants, performed simultaneously with various plants and using physicochemical analyses as well as toxicity tests. Therefore, the conducted studies focused on assessing the removal of pollutants from leachate by physicochemical analyses and toxicity tests. The leachate was collected from four municipal waste landfills of different ages (2 non-operational facilities and 2 active). The studies were conducted for two biological systems: using emergent macrophytes (Phragmites australis) and submergent macrophytes (Ceratophyllum demersum L.). It has been observed that efficiency of biological treatment of leachates with Phragmites australis and Ceratophyllum demersum shows significant differences at lower concentrations of solutions. Even after the treatment with Phragmites australis and Ceratophyllum demersum, the analyzed leachate samples produced a toxic effect on the test organisms. A reduction or no toxicity of the leachate after the biological treatment was observed only in some cases. The observed effects of the biological leachate treatment were not conclusive. Particular attention should be paid to the persistent toxicity, which can pose a real threat to the environment when discharging leachates after treatment.

Investigating emergent macrophytes establishment rate and propagation towards constructed wetlands efficacy optimization

Constructed wetlands have become a widely used tool for reducing nutrient loading from agriculture drainage water running to aquatic ecosystems. To ensure a high nutrient removal efficiency, it is often suggested to use macrophytes to retain or remove nutrients via uptake and through the denitrifying biofilm. In Europe, Phragmites australis and Typha spp are the most commonly used aquatic plants in constructed wetlands (CWs) with free surface flow, and these species often form monocultures in the wetlands. In order to achieve a more diverse vegetation, there is a need to introduce more plant species. Creating a mass production of plant material reduces both handling time and the risk of depleting and disturbing vegetation in natural habitats such as streams or lakes. However, a successful and continuous production of such material during growing seasons requires knowledge of the selected species' establishment and propagation. We examined the relative growth rate (RGR) of six emergent macrophyte species collected from streams and small lakes located in Mid Jutland (Denmark), in seasonal experiments from March to October in order to determine the most efficient time period for their propagation. We found that all species had highest RGR in June, and that several species showed high growth efficiency from April to August. The results showed that it is possible to have a full production of emergent macrophytes throughout the growing season, and therefore, we suggest to propagate plants for use in constructed wetlands in order to enhance biodiversity and ecosystem functioning.