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  Intermediate dark fermentation as a platform technology for chemical recycling and biorefineries in the water sector PhD


   Faculty of Engineering and Physical Sciences

  Dr Y Bajón Fernández, Dr L Alibardi  Applications accepted all year round  Funded PhD Project (UK Students Only)

About the Project

This exciting fully funded PhD, with an enhanced stipend of £20,000 per annum, will investigate resource recovery opportunities from sewage sludge with dark fermentation as core enabling technology. Current state of the art for sludge treatment is focussed on biogas and digestate generation via anaerobic digestion, as sources of renewable energy and organic fertilizers, respectively. This project works collaboratively with UK water utilities to identify and develop alternative value propositions, investigating the role of dark fermentation in transitioning sludge treatment centres into true biorefineries, where available carbon can be recovered and used for wastewater treatment or converted into high value chemicals for external use. 

The Water-Wiser Centre for Doctoral Training provides the successful applicant with a unique opportunity to collaborate with industry in solving a real need for the water sector, while remaining part of a cohort of CDT PhD students. The successful candidate will work within a multi-disciplinary academic team and have regular exposure to expert industry stakeholders, increasing employability on project completion. 

We are an inclusive and diverse doctoral centre and welcome applications from all highly motivated individuals, regardless of background, identity or disability .

Reducing dependency on external chemical supplies for wastewater treatment is a strategic priority for the water sector, in order to sustain a resilient treatment that is not exposed to availability and costs of chemical supplies. Separately, decarbonising the chemical supply for treatment plays a key role on the long-term ambition of water utilities to deliver a low carbon service to customers. The strategic role of biorefineries in generating bio-based materials that can substitute fossil-based fuels and chemicals is recognized internationally, with their importance highlighted in the European Union Bioeconomy Strategy (2022).

The potential of transitioning sludge treatments centres into true biorefineries by implementing dark fermentation has been stated for the water sector, both for treatment of sewage sludge alone or in co-treatment with other organics wastes. In the short term, intermediate dark fermentation can offer a route to recover volatile fatty acids (VFAs) for internal use within wastewater treatment plants (WWTPs), suppressing the need for external carbon sources for biological nitrogen and phosphorus removal (BNPR) and providing a carbon neutral chemical source. In the longer term, VFAs, as the most versatile platform chemical extractable form sewage sludge, can be physically extracted or chemically/biologically converted to a range of high value products and fuels, with bioplastics, animal feed, biogas, hydrogen as examples. Although underexplored for sludge feedstocks, the potential of dark fermentation to generate green hydrogen is also a concomitant benefit. 

This project aims to develop dark fermentation as an enabling technology for circular economy in the water sector, with individual objectives as:

  1. To provide an internal carbon source for BNPR that reduces reliance on external chemical purchase 
  2. To define the operational framework for sewage sludge dark fermentation that will result in optimized VFAs yields while controlling VFA profile
  3. To inform the technical feasibility and environmental benefits of a dark fermentation and AD combined flowsheet for the UK context
  4. To quantify the market potential of implementing dark fermentation to sell VFAs as platform chemicals 

Cranfield University is a unique learning environment with world-class programmes, unrivalled facilities and close links with business, industry and governments, all combining to attract the best students and teaching staff from around the world. Research students at Cranfield benefit from being part of a dynamic, focused and professional study environment and all become valued members of the Cranfield Doctoral Network. This network brings together both research students and staff, providing a platform for our researchers to share ideas and collaborate in a multi-disciplinary environment.

This project is sponsored through the Water-WISER CDT, offering a unique opportunity to contribute to the generation of new knowledge to improve water and waste infrastructure and services for the poorest and most marginalised members of our global community. This Centre for Doctoral Training (CDT) is funded by the UK Engineering & Physical Sciences Research Council (EPSRC); however it is highly interdisciplinary, spanning Engineering, Physical & Environmental Sciences, Public Health, Economics and Social Sciences.

This project will advance thinking into transitioning sludge treatment centres into true biorefineries. It will define the operational framework for sewage sludge dark fermentation that will result in optimized VFAs yields while controlling VFA profile, informing the technical feasibility and environmental benefits of a dark fermentation and anaerobic digestion combined flowsheet for the UK context. The project findings will support the water industry deliver on its aspirations to reduce dependency on external chemical supplies and reduce the carbon footprint of its operations. 

The successful candidate will have the opportunity to work alongside the industry sponsors and gain significant experience in industrial research while developing the fundamental science to enable sludge biorefineries. The project also provides an enhanced financial package with an annual tax-free stipend of £20,000. Water-WISER CDT also provides fully covered fees, a sum of up to £20,000 to cover students’ attendance to international conference, training needs, field work, consumables, etc. It is expected that the candidate will attend and present at national and international conferences.

At the end of the project the successful applicant will be very well positioned to have a highly successful career in the water sector or in an academic role. We will help you develop into a dynamic, confident and highly competent researcher with wider transferable skills (communication, project management and leadership) with an international network of colleagues.

This is an applied PhD, with the student having regular interaction with the stakeholders from UK water utilities and being exposed to state-of-the-art industrial practices in sludge treatment; all providing a unique learning experience and opportunities for further employability. The experimental work will be conducted at Cranfield’s UKCRIC funded Bioresource Technology Lab, alongside a dynamic team focussed on supporting water and waste utilities increase resilience and meet their sustainability targets.

Engineering (12) Environmental Sciences (13)

Funding Notes

Sponsored by EPSRC through the Water-WISER Centre for Doctoral Training and multiple UK water utilities, this programme will provide a bursary of up to £20,000 (tax-free) plus student fees for four years. The sponsorship also includes project consumables and a package to support training needs and attendance to national and international conferences of the successful applicant.

The studentship is open to UK nationals.

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