Project Highlights:

  • The PhD research student will work with project partner Heathrow Airport to generate new scientific evidence on de-icer transport and impact to inform pollution mitigation measures.
  • S(he) will conduct fieldwork on and around the airport, laboratory experiments and process-based modelling, developing strong research and transferable skills through the project.
  • The topic is ideal for those with chemistry, engineering or ecology backgrounds who would like their research to be directly applicable to current environmental problems.


This project is an exciting opportunity to conduct scientific research on water quality in collaboration with Heathrow Airport. Millions of litres of de-icers are sprayed on aircraft each winter at airports worldwide. However, a more detailed scientific understanding of de-icers, their transport from airports to surrounding waterbodies and the mechanisms of impact to aquatic ecological communities is required to inform airfield operations and pollution mitigation. This project proposes an interesting combination of field research, laboratory experiments, and pollution transport modelling to answer fundamental questions about pollutant transport and ecological impact that will have immediate, real-world impact.

Aircraft de-icers are widely recognised as pollutants of surface waters, and strict guidelines exist in many countries to limit their discharge to rivers, lakes and wetlands. But even when these guidelines are respected, biological organisms indicative of poor water quality are still observed in waterbodies around and downstream of airports during winter months. This ecological effect is most strikingly represented by benthic biofilm growth on riverbeds. These biofilms are known commonly as sewage fungus, though are primarily composed of filamentous bacteria. Previous studies have suggested that the organic content of the active ingredient (e.g. glycol) is fueling the growth of biofilms, but more research is needed on the individual and interaction effects of water quality and ecological parameters on biofilm growth.

With better knowledge of how de-icers are driving the poor ecological status of rivers around airports, opportunities arise to alter airport operations or introduce new pollution mitigation measures. However, to maximise the water quality reduction benefits of these potential measures, the transport, transformation and fate of the pollutants as they travel through the airport drainage networks and treatment systems must be investigated and quantified.

De-icing is necessary for the safe operation of aircraft during cold weather. Through this co-designed project with Heathrow Airport, new scientific evidence will be generated on the physical, chemical, biological and ecological processes controlling de-icer transport and impact. The PhD student will gain essential research skills and work in close partnership with Heathrow Airport to help them further reduce their environmental impact.

Figure 1: Heathrow Airport is surrounded by rivers and reservoirs that are affected by a number of anthropogenic pressures (©Crown copyright and database rights 2018 Ordnance Survey). Inset: Biofilm growth in the River Crane, located to the east of the airport (Photo credit: Heathrow Airport)


A combination of field monitoring, laboratory experiments and water quality modelling is proposed in this project. Monitoring of de-icers concentrations and discharges will be conducted in the drainage network and treatment system in Heathrow Airport and in the River Crane that receives treated stormwater run-off from the airfield. Additional monitoring in the river will record the timing and concentration of de-icers and other pollutants relative to storm events and the seasonal extent of biofilm cover on the riverbed. Using this information, laboratory studies (e.g. Bioscreen and mesocosms) will be conducted to investigate how de-icer chemicals individually and in combination with physical and chemical variables affect the growth of biofilm constituents (e.g. Sphaerotilus natans) and the transformation and degradation of de-icers on land and in water. The final component of the study is the calibration and validation of an existing process-based pollutant transport model to predict de-icer run-off.

Training and Skills

The combination of methods proposed in this study will provide the PhD research student with the opportunity to develop a broad range of research and transferable skills. The student will receive training from their supervisors on field survey design, ecological and geomorphological fieldwork, laboratory skills, multifactorial experimental design and statistical data analysis. They will also receive support in the set-up, calibration and validation of process-based hydrological and water quality models. The supervisors will work closely with the student to guide them in the planning of their research, selection of methods, interpretation of results, writing of scientific papers and presentation at academic conferences.


Year 1: Critical review of water quality transport models. Selection of a model for the study based on agreed criteria. Initial model calibration based on existing hydrological and water quality data. Design and commencement of the field monitoring within and around Heathrow Airport. Participation in training workshops with the CENTA DTP and at Cranfield University. Successful completion of 1-year review.

Year 2: Continuation of field monitoring, the preliminary results of which will inform the design of laboratory experiments. Multifactorial designed experiments to be conducted using Bioscreen and mesocosms with varying water quality and hydrodynamic conditions. Presentation of results at an academic conference. Completion of a one or more chapters for publication in an academic journal. Revision of the water quality model.

Year 3: Completion of the field monitoring, plus statistical analysis and interpretation of the results. Drafting of an academic paper on the fieldwork. Targeted investigations/monitoring of water quality in the drainage network and treatment system at Heathrow Airport for further validation of event-based modelling. Submission of final thesis by the end of registration.


Partners and collaboration (including CASE)

The student will benefit from a close partnership with the Environment team at Heathrow Airport. They will provide access to sites on and around the airport, guidance on study design and deliverables, and regular feedback on research results. The Environment Team has kindly offered to host the student at their offices next to the airport to facilitate data collection and provide the student with industrial experience. The Environment Agency has also expressed an interest in the research as a part of their ongoing monitoring and improvement of the River Crane, a Water Framework Directive waterbody.

Further Details

For further information or an informal chat, please contact Dr Robert Grabowski, r.c.grabowski@cranfield.ac.uk.

The student will be based at the Cranfield campus at Cranfield in Bedfordshire - https://www.cranfield.ac.uk/About/How-to-find-Cranfield