Lagunage

vignette|upright=1.5|Schémas de lagunage naturel. vignette|upright=1.5|Le lagunage peut aussi être linéaire et avoir vocation de corridor biologique (utilisant un fossé ou ici une berge de canal, en bordure de la Deûle, en aval de Lille). Réalisation : VNF (photo de 2004). vignette|upright=1.5|Des berges lagunées ont été créées (2010) par VNF (Voies navigables de France), en guise de mesure compensatoire à la mise à grand gabarit de l'Escaut dans le nord de la France. vignette|upright=1.5| Le lagunage lors de sa construction a été structuré formes complexes et méandres de manière à allonger l'écotone eau-sol et à mieux épurer l'eau de l'Escaut. Les pentes très faibles défavorisent l'installation du rat-musqué ou du ragondin vignette|upright=1.5|Ce lagunage est alimenté en eau par l'Escaut lui-même ; passivement en l'absence de trafic ou plus "activement" lors du passage de chaque péniche (qui produit une vague avec surpression puis dépression). vignette|upright=1.5|Cette berge lagunée

Analysis of loads, water quality and certain biological production on the Kis-Balaton Water Protection System

Elise Kaiser

Wetlands are important ecosystems: they are habitats for many key species and act as natural regulators of the environment. They filter water and remove pollutants with the help of plants. Constructed wetlands are artificial wetlands built to treat mainly wastewaters. These artificial ecosystems can also be used for freshwater treatment, such as river water. The Kis-Balaton Water Protection System (KBWPS) is one of them and the main goal of the system is to treat the River Zala water before its entrance in the Lake Balaton. The two mains objectives are to avoid the eutrophication of the Lake Balaton and improve the wetland ecosystems. It is a vast constructed wetland of 71 km2, situated at Southern part of Lake Balaton, in Hungary. The goal of this thesis was to analyze the loads, water quality and biological production of the KBWPS. Interpretation of three different sets of data and field work was carried out. The first set was about inflow and outflow data, from which the removal rates of different nutrients on a long time period were computed. The second data series contained regular water quality monitoring data along the flow path and the goal was to study the inner processes happening in the KBWPS. The last data set was collected on the field and included basic water properties and some biological and physico-chemical measurements, such as primary production or tecton analysis. It allowed to differentiate the water types of the system and their properties and to better understand the inner processes, particularly the biological characteristics of the system. The interpretation of the data series gave background to understand the processes occurring within the system and it helped to characterize the actual different water groups. It drew the main lines for possible more detailed analysis. This work was partly connected to a project aiming at the development of a monitoring system that serves a better management of the KBWPS. Several conclusions can be drawn from the results found in this thesis: • General conclusions on the system, which could apply to other systems of the same type. • Specific conclusions about the operation of the system, which would refer to this system only. • Some management and monitoring suggestions for the future system.

2013

Constructed wetland for the treatment of surface waters from combined sewer overflow (CSO) of La Chaux-de-Fonds

Blaise Adrien Devaud

The Doubs river is an ecosystem-rich river which is threatened by several anthropic activities. The three dams placed in the river as well as the discharge of pollutants contribute to the degradation of its natural habitats. The city of La Chaux-de-Fonds is directly concerned by this issue. The combined sewer overflow (CSO) waters generated by the city discharge in la Ronde, an affluent of the Doubs. These waters represent a potential threat to the Doubs water quality, this is why the authorities of La Chaux-de-Fonds need to take measures to limit the impacts of these waters in the natural environment. These measures have to be taken without causing excessive costs. Several solutions have been considered according to the objectives set during the development of the « plan d’évacuation des eaux (PGEE) » of the city. The implementation of a constructed wetland was the selected solution. This system is widely used in a number of European countries and especially in France, but is not yet much developed in Switzerland. Topographic and design constraints have lead the choice of a vertical flow constructed wetland. Its technical feasibility has been deeply studied. The design of the constructed wetland has been examined using the simulation tool Orage (which is currently in phase test in the IRSTEA research institute in Lyon). A second tool, the Rebeka software, allowed to determine the impact of the CSO water on the water quality of the Doubs. The STORM approach helped to integrate these impacts in the design of the system from the beginning of the the project. The costs of the project are detailed in investment costs for the building of the wetland and operation costs which represent essentially functioning and maintenance costs. The treatment system consists of three planted filters which operate in parallel. Simulation results demonstrate that the objectives of the project are fulfilled. The installation has a removal efficiency of 29% on ammonium, 44% on COD and 95% on TSS. The initial investment is 3.6 million Swiss francs. This system offers a solution to resolve pollution issues originating from the CSO waters of the city of La Chaux-de-Fonds with a reasonable initial investment.

2016

Analysis of loads, water quality and certain biological production on the Kis-Balaton Water Protection System

Elise Kaiser

2013

Constructed wetland for the treatment of surface waters from combined sewer overflow (CSO) of La Chaux-de-Fonds

Blaise Adrien Devaud

2016

Analysis of loads, water quality and certain biological production on the Kis-Balaton Water Protection System

Constructed wetland for the treatment of surface waters from combined sewer overflow (CSO) of La Chaux-de-Fonds

Comprehensive process-based modelling of sand filters and subsurface flow constructed wetlands.

Analysis of loads, water quality and certain biological production on the Kis-Balaton Water Protection System

Constructed wetland for the treatment of surface waters from combined sewer overflow (CSO) of La Chaux-de-Fonds

Comprehensive process-based modelling of sand filters and subsurface flow constructed wetlands.