Fouling Control of Water Treatment Membranes through Optimal and Sustainable Cleaning Strategies

Membrane fouling – the deposition of organic and inorganic matter on the membrane surface – is a major technical obstacle affecting membrane-based water treatment processes. Fouling results in decreased membrane permeance, selectivity, and shorter useful life due to irreversible fouling. Despite significant efforts to mitigate fouling through, e.g., low-fouling membrane coatings, fouling is inevitable due to the high convective fluxes driving foulants to the membrane surface. Consequently, physical and chemical cleaning strategies, known collectively as cleaning-in-place (CiP) protocols, are indispensable to ensure the sustainable use of membrane technology in water treatment.

Most CiP formulations entail proprietary mixtures of buffered surfactants and chelants that dissolve organic foulants and disperse colloidal metal-organic complexes. Application of CiP solutions often follows manufacturer-specified cleaning conditions, including cross-flow velocity, duration and frequency of cleaning cycles. Such operating conditions, however, are not optimised for specific feed water and foulant chemistries. Moreover, the important influence of CiP solution temperature is often neglected. Solution temperature plays a key role in membrane cleaning, as the interactions responsible for foulant adhesion to the membrane become weaker with rising temperature1. However, the role of temperature in CiP has not been studied systematically. Incomplete knowledge about the influence of operating conditions has hindered development of efficient CiP protocols.

This PhD project will formulate tailored CiP strategies for membranes in Scottish Water (SW) treatment plants. The overarching goal is twofold: i) to identify the CiP temperature resulting in optimal membrane performance; ii) to identify CiP formulations (or mixtures thereof) suitable for application at ambient feed water temperatures (i.e., in cold water). Considering that CiP at SW membrane plants is often carried out at ambient water temperature (Tamb = 10 °C or lower), we anticipate significant improvements in cleaning efficiency if CiP were carried out at slightly higher temperatures. The cost of CiP operations at above-ambient temperatures will be weighed against the improvement in process performance (stemming from mitigated fouling) by a technoeconomic analysis. Lastly, we will perform a life cycle assessment of CiP protocols to identify CiP candidates meeting SW’s sustainability goals.

Training and mentoring

This project offers a unique training opportunity in the fundamentals of colloid and interface science, as well as membrane-based processes for water quality control. The student will be mentored by a supervisory team with complementary expertise, who will provide training in a wide variety of experimental techniques. In addition, the student will acquire industrial experience through a placement at a Scottish Water membrane plant.


(1) BinAhmed, S.; Hozalski, R. M.; Romero-Vargas Castrillón, S. Feed Temperature Effects on Organic Fouling of Reverse Osmosis Membranes: Competition of Interfacial and Transport Properties. ACS ES&T Eng. 2021, 1 (3), 591–602.

(2) Porcelli, N.; Judd, S. Chemical Cleaning of Potable Water Membranes: The Cost Benefit of Optimisation. Water Res. 2010, 44 (5), 1389–1398.

Please note that applications will be reviewed on a continuing basis until the position is filled. Thus, the advert might close for applications before the closing date.

Further Information: 

Further information about the supervisor (Dr S Romero-Vargas):

Further information about the co-supervisor (Prof A Lips):

The University of Edinburgh is committed to equality of opportunity for all its staff and students, and promotes a culture of inclusivity. Please see details here:

Closing Date: 

Sunday, June 22, 2025

Principal Supervisor: 

Assistant Supervisor: 


This is a challenging and ambitious project, requiring a student who is dedicated and enthusiastic about asking, and tackling, fundamental and applied problems. The successful applicant will have been awarded an undergraduate degree at the time of appointment (1st Class or high 2:1, preferably supported by an MSc) in chemical engineering, chemistry, materials science, physics, environmental engineering, or a cognate field. Strong background in physical sciences is required, along with excellent oral and written communication skills in English. Prior research experience in colloid & interface science is highly desirable. While the project is primarily experimental, good or strong quantitative skills are also highly desirable.

Further information on English language requirements for EU/Overseas applicants.


Applications are welcomed from self-funded students, or students who are applying for scholarships from the University of Edinburgh or elsewhere, as explained below.

PhD studentships managed by the School of Engineering at the University of Edinburgh are available every year through a competitive process.

Applicants interested in applying for a University-administered award should e-mail the supervisors (, as soon as possible to begin discussions, explaining how your experience meets the Applicant Requirements given above. Application deadlines vary from mid-January to late March.

Further information on funding options.

Please note that most studentships are available only to Home Students (International students not eligible).

To qualify as a Home student, you must fulfil one of the following criteria:

- You are a UK student

- You are an EU student with settled/pre-settled status who also has 3 years residency in the UK/EEA/Gibraltar/Switzerland immediately before the start of your Programme.


Informal Enquiries: 

Dr Santiago Romero-Vargas Castrillon:; Prof Alex Lips: