Dynamics of pollution transport in constructed wetlands: identification and quantification of underlying physical mechanisms of solute and solid (micr

Dynamics of pollution transport in constructed wetlands: identification and quantification of underlying physical mechanisms of solute and solid (microplastic) transport. Constructed wetlands (CWs) are ecologically-engineered systems that use soil, vegetation and organisms to treat water and remove solute and solid pollution. It is the interplay between water-vegetation-soil that governs the wetland physical, chemical and biological treatment processes.

These 'Natural Capital' assets are one of the most effective measures to treat municipal and industrial wastewater, greywater and storm-water runoff. Dynamics of water movement plays a key role in the removal of pollutants, as it influences the hydraulic residence time (contact and activity time) for treating the pollutants. Plant communities have a prominent effect on the wetland hydrodynamics and performance, as they generate flow resistance, changes the velocity field and affect mixing characteristics, enabling suspended material to fall to the wetland bed.

Seasonal variation in vegetation growth and die-back influences the performance of the system. In addition, the microbial community will respond over time to the organic and metal pollutants that are constituents of the effluents. However, critical knowledge gaps remain in sources and fate of pollutants in wetland ecological systems.

The main aim is to identify and quantify key mechanisms that govern the transport and fate of pollutants using laboratory and field-based data from wetlands located within the Norfolk Rivers Trust. This project will also explore the interaction of microplastics with soil and ecological systems within wetlands to understand the potential for ecotoxicity in biological organizations.

These mixing and transport mechanisms will be investigated using state of the art fluorometric and experimental fluid dynamics methods as well as our innovative technology for microplastic staining. The new insights offered by this project will enable understanding the dynamics of pollutant transport in wetland systems. The algorithms which will be developed within this project will be coupled with existing multi-phase flow models in order to simulate pollutant transport under various hydro-climates.

Hence this project will provide a step change in environmental protection and integrated catchment management by understanding and optimising the performance of constructed wetland natural capital assets, and significantly, be influential at a time of considerable investment in these systems by the water industry.