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

 (via FindAPhD)
University of Warwick
Warwick, United Kingdom
Position Type: 
Organization Type: 
University/Academia/Research/Think tank
Experience Level: 
Not Specified


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About the Project


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.


This project will undertake laboratory-based physical modelling measurements and fieldwork data collection to understand the dynamics of pollutant transport in wetlands. We will create an interacting mesocosm wetland environment using the world class experimental facility at Warwick Water Laboratory. Fluorometric tracing along with novel particle staining techniques will be applied, alongside planar laser-induces fluorescence(PLIF) and particle image velocimetry(PIV/PTV), with the aim of identifying and quantifying underlying physical transport mechanisms of pollutants and the impact of hydraulic conditions on the transport and fate of the pollutant. The experimental and fieldwork investigations will explore the interactions of microplastics with sediment bed of fluvial systems with the aim of identifying and quantifying the

hyporheic exchange processes governing pollutant interactions with the wetland sediment bed. A comprehensive set of tests will be conducted to quantify transport and fate of different types of microplastic polymers (varying in density, shape and size), across a wide range of environmental flows.

Partners and collaboration:

The project would be supported by Norfolk Rivers Trust(NRT) and Anglian Water. The Student will have the opportunity of data collection in wetlands operated by NRT and Anglian Water. Furthermore, there will be internship and placement opportunity for the student at NRT to engage with projects in pollution risk-management, catchment planning and management.

Possible timeline:

Year 1: Basic research skill training; literature review and familiarisation with existing datasets and analysis techniques for hydrodynamic

and fluorometirc data. Preparation for experimental studies. Familiarisation with field test sites and constructed wetland design, planning, construction, and management.

Year 2: Comprehensive laboratory and field-based hydrodynamic and fluorometric measurements for solute and microplastic transport under various hydraulic conditions within wetlands. Investigating the impact of particle density, size and shape on the transport and fate of


Year 3: 

Detailed analyses of laboratory data, deriving mathematical algorithms suitable for simulating solute and microplastic transport under various

environmental flows and inclusion to the existing numerical codes. Writing the thesis will take place during the final year.

Funding Notes

From the 2021/22 academic year UK Research and Innovation (UKRI) funding is open to both UK and International research students as detailed on the UKRI website. Awards for both Home students and International students cover Home level tuition fees and provide a stipend at the standard UKRI rate to support living costs. International students should note that UKRI will not fund the difference in Home level tuition fee and International level tuition fee. Funding for this may be available from other sources but specific guidance on this is currently not available. Please watch out for updated information on our website.