Optimised flocculation processes in water treatment
- Supervisors: Professor John Bridgeman
This is a truly multidisciplinary project bringing together engineering, mathematics, physics and chemistry to improve our understanding of water treatment.
The coagulation and flocculation processes (i.e. the chemical destabilisation of colloidal particles and subsequent agglomeration via mixing) represent two key processes vital to the successful production of potable water. Coagulation brings about a change in the nature of small particles, rendering them unstable, whilst flocculation encourages particle agglomeration via gentle mixing and the formation of irregularly-shaped, loosely connected flocs. Ineffective coagulation or flocculation results in poorer quality feed water to clarifiers and filters, potentially jeopardising treated water quality and increasing operational costs. Despite the importance of optimised coagulation and flocculation for water quality, operational and chemical usage efficiency purposes, flocculator design for water treatment has traditionally been based on empiricism due to a lack of accurate flocculation models. A review of the literature demonstrates that this is an area of research that has been overlooked and consequently the industry lacks robust optimised flocculator design rules based on fundamental understanding of the interrelation between water chemistry, flocculation mechanisms and fluid dynamics. Whilst much previous work in the field has examined optimisation of flocculation chemistry, there is a lack of work which considers both the chemistry and hydrodynamic environment within which flocculation processes occur.
The principal aim of this project is to develop further our understanding of the flocculation process in water treatment, through accurate numerical simulation at laboratory and full scales in order to provide a much-needed step change in flocculator design processes.
The specific project objectives underpinning this aim are to:
1. investigate and determine at lab scale, the precise mechanisms involved in particle agglomeration, breakage and regrowth, and the interactions between turbulence scales and water chemistry for the broadest range of water types.
2. determine the most appropriate method of simulating the flocculation process in water treatment using a modelling strategy that will consider the use of computational fluid dynamics, discrete element modelling and population balance modelling for laboratory scale applications.
3. simulate flocculation processes at full scale and to validate these models with appropriate field data.
4. develop criteria for successful, optimised flocculation for a wide range of raw waters, coagulant types and doses, and flocculators that will be universally applicable and will facilitate a reduced water treatment carbon footprint.
The laboratory work will make use of start-of-the-art simultaneous 2D3C Particle Image Velocimetry and Planar Laser Induced Fluorescence to study turbulent mixing, and a laser diffraction system for accurate floc size characterisation. Computational work will make use of the University of Liverpool high performance computing resource, the parallel Linux cluster, Barkla.
Candidates will have, or be due to obtain, a Master’s Degree or equivalent from a reputable University in an appropriate field of Engineering. Exceptional candidates with a First-Class Bachelor’s Degree in an appropriate field will also be considered.
Candidates wishing to apply should complete the University of Liverpool application form applying for a PhD in Civil Engineering and uploading: Degree Certificates & Transcripts, an up-to-date CV, a covering letter/personal statement and two academic references.
Candidates wishing to discuss the research project should contact the primary supervisor Professor John Bridgeman [firstname.lastname@example.org], those wishing to discuss the application process should discuss this with the School Postgraduate Office [email@example.com].
How to apply
Open to UK applicants
This Scholarship is for UK [home] students only and has a financial package including: annual stipend at the UKRI rate [currently £17,668 per annum for academic year 2022-23], student fees and a research support grant [for conferences & travel, consumables etc] for 3 academic years.
Pougatch, K., et al., 2021, Population balance modelling of dense clay slurries flocculation, Chemical Engineering Science, 231, 116260, ISSN 0009-2509, https://doi.org/10.1016/j.ces.2020.116260.
Bridgeman, J. et al., 2010, The development and use of CFD models for water treatment flocculators, Advances in Engineering Software, 41, 99-109, https://doi.org.10.1016/j.advengsoft.2008.12.007.