Growing applications of membrane processes in water and energy pose new and interesting demands on both membranes and its process design. At Imperial, our research spans from new membrane development to its applications in separation and reaction. We have developed new fabrication techniques for polymeric, ceramic and metallic membranes, especially in hollow fibre/micro-tubular geometry with diameter between 0.5 and 2 mm. These membranes have unique purposely designed wall structures to suit different applications, including filtration, gas separation, emission control and fuel cells.

The designed membranes with the unique wall structures can be further functionalised with advanced nanomaterials or catalysts, and multiple functions can be integrated into one single-step. The functional nanomaterials currently being investigated include graphene, graphene oxide, metal-organic frameworks (MOFs), and they can be in the form of thin films deposited on the surface of the membrane support or granules packed in the unique wall structures of the membrane. For example, we have developed micro-tubular graphene oxide thin films to extract water from organic solvents, and a novel adsorption/filtration column containing MOF nanoparticles to get rid of bacteria and heavy metal ions from contaminated water. The micro-tubular or micro-monolithic membranes can also be incorporated with catalysts to construct micro-reactors or fuel cells. Our research on these micro-reactors has been regarded as one of the most important progresses in the field. This presentation will focus on the new membrane fabrication techniques and applications of these purposely designed membranes in separation and reaction.

The efficiency of water treatment systems in virus removal is affected by viruses’ propensity to attach to or leave surfaces such as membranes, biofilms, and suspended matter. Thus, understanding virus adhesion is important for effective virus detection – the task of paramount importance for public safety. The challenge is especially acute in “viral reservoir” environments such as water reuse facilities. The presentation will summarize results from several recent studies aimed at elucidating physicochemical bases of virus adhesion onto archetypal surfaces including polymers (e. g. polymers used to make membrane filters and masks) and various fomites (e. g. ceramics and passivated metals). Adhesion of human viruses and bacteriophages is explored using a combination of XDLVO modeling, adhesion tests based on QCM-D measurements, and membrane separation experiments. The results are interpreted based on physicochemical properties of viruses and target surfaces, which are typified on the basis of their surface energy components. We show that hydrophobic and electrostatic interactions govern virus attachment while van der Waals interactions play a relatively minor role. In higher ionic strength solutions, the extent of virus attachment correlates with the free energy of virus-surface interfacial interaction. The information on the efficiency of virus attachment to materials as a function of their surface energy components can guide screening and selection of materials for virus removal and detection applications. More broadly, the proposed methodology can help design anti-adhesive surfaces, develop surface cleaning solutions and protocols, and inform transport and fate models for viruses in environments such as water reuse facilities and other settings of critical importance for public health.

Like all other sectors, the water sector is also undergoing rapid digitalisation providing new opportunities for improved, more efficient and economical services. Digital tools can efficiently contribute to membrane applications, and an increasing number of research and applications are reported.
Modelling of the membrane processes has been the traditional approach to using digital tools in the membrane processes. They were used to optimise the flux and predict and reduce fouling. The recent models also contribute to the optimisation of membrane structures.
The use of ANN, machine learning and fuzzy logic in process control has significantly increased in recent years; Flux estimation of dynamic ultrafiltration using machine learning is an example. The use of advanced process control to optimise combined systems, such as pre-coagulation and ultrafiltration, has improved process efficiency and economics. Successful applications of novel approaches to predict and optimise the flux, fouling and cleaning processes are documented, although they may are still in the pilot scales.
Using virtual and hybrid sensors in water quality measurements also contributes to improved process control in membrane processes. Surrogate parameters can contribute to understanding and control of fouling. The application of spectroscopic fingerprints, including fluorescence excitation-emission matrix (EEM) coupled with parallel factor analysis (PARAFAC) are promising examples.
The Digital Twins are developed for several unit processes and combined processes. The development of Digital Twins in membrane processes has also become a reality with the development of models, surveillance and control systems.
This presentation will give an overview of the State-of-the-Art use of digital tools in membrane processes and discuss some research trends.