Development of Radiometric Methods to Measure and Study Hydrodynamics of Constructed Wetlands

The use of Constructed wetlands (CWs) can be a very efficient and economic technology for wastewater treatment. They can be applied to all types of wastewaters including sewage, storm water runoff, industrial and landfill leachate. Constructed wetlands differ from conventional wastewater treatment, which involves physical, chemical and biological processes and also required mechanical and physical infrastructure. Constructed wetlands rely on the natural functions of wetland flora and fauna to treat contaminants in the water. Despite their advantages, they are difficult to optimise as pollutant removal strongly depends on the flow hydrodynamics, concerning which available information is often inadequate. The use of radioactive tracers promises to be an effective approach to measure the hydrodynamics of CWs and to increase our knowledge of the operation of CWs. For this purpose, the project intends to develop the use of radioactive tracers and associated methodologies through the assessment of CWs hydrodynamics with proper modelling tools; to find the best radioactive tracer and to develop the best methods (tracer quantity, injections and measurement points, etc). Furthermore, the project will help identify critical points and required water path lengths to process a given flux of biodegradable organic matter with the assistance of models. Thus models representing the different types of flow in CWs will be for enhanced CW hydrodynamics. Constructed treatment wetlands have evolved during the last five decades into a reliable treatment technology which can be applied to all types of wastewater including sewage, industrial and agricultural wastewaters, landfill leachate and stormwater runoff. Pollution is removed through the processes which are common in natural wetlands but, in constructed wetlands, these processes proceed under more controlled conditions. All types of constructed wetlands are very effective in removing organics and suspended solids, whereas removal of nitrogen is lower but could be enhanced by using a combination of various types of CWs. Removal of phosphorus is usually low unless special media with high sorption capacity are used. Constructed wetlands require very low or zero energy they are difficult to optimise and pollution removal strongly depend on their hydrodynamics. However there is no real good method to measure hydrodynamics of CW except for radioactive tracing that seems very promising.For this purpose, the project intends to develope the use of adioactive tracers and associated methodologies throught the assessment of constructed wetlands hydrodynamics with proper modelling; to find the best tracer and to develop the best methods (tracer quantity, injections and measure points, etc). Besides, to identify critical points and required water paths lenghts to process a given flux of biodegradable organic matter with goes with the development of models that will show the proper modelling for CW hydrodynamics.