Photocatalytic Anodic Metal Membranes for Micropollutant Removal

The accumulation, in the environment and in human food supply chain, of organic micropollutants, highly toxic substances such as drugs, hormones or endocrine disruptors found at very low concentrations in water, represents today one of the biggest challenges to public health and the environment in the UK and other developed countries. As a large number of compounds, including common anti-inflammatories, antibiotics, hormones, pesticides and and herbicides, is added to the priority substances watch list for future regulation, there is an urgent need for novel technologies capable of degrading micropollutants safely and without generating significant increases in carbon emissions of the water industry, already accounting for about 5% of UK emissions.

Legacy technology comprising the majority of water treatment plants in the UK and other developed countries cannot remove micropollutants, requiring an additional treatment step to be added to the water treatment train. Alternative technologies currently being tested in the UK and abroad all have limitations, in terms of high energy costs or high capital costs or production of toxic by-products, which require further removal. The urgency of addressing this issue is witnessed by estimates of multi-billion pound capital investments and £B/year operating costs faced by the UK water industry, to address impending legislation mandating the removal of micropollutants. In fact, the European Water Industry Platform has concluded that the chance of removing micropollutants without significant increases in energy consumption with current technology is 'very low', and that this can be achieved only by 'leapfrogging traditional, polluting and resource-intensive technologies', a view shared by the UK government.

Photocatalysis, considered the leading technology to treat micropollutants, suffers from a twin-set of limitations that have hindered more widespread adoption so far. Slurry reactors, where wastewater is mixed with a slurry of photocatalytic nanoparticles under UV illumination, can effectively degrade micropollutants but require costly downstream retention of the particles to avoid their leaching into the environment. Reactors with immobilised catalysts, on the other hand, have significantly lower activity due to lower contact area and higher light scattering. Furthermore, preliminary evidence of potential adverse health effects arising from the accumulation of nanoparticles in the environment, has convinced UK's Environment Agency, DEFRA and health authorities to block their use in water treatment.

My vision as an EPSRC Established Career Fellow in Water Engineering is to safely degrade micropollutants without significantly increasing carbon emissions or producing toxic by-products. I will achieve this by creating novel photocatalytic nanoporous anodic metal foams, combining the high surface area of slurries and the stability of immobilised systems requiring no downstream removal. The combination of a metallic core and a metal oxide coating will enable boosting photocatalytic activity by using a small electrical potential, decreasing the need for low-efficiency electricity-to-light conversion.
My ambition is to address the twin challenges that have so-far hindered the use of photocatalysis in water treatment: the potential leaching of photocatalytic slurries in the environment and the low efficiency of UV light illumination, which translates in low activity, for immobilised photocatalysts.

Societal and Economic Impact
Water sanitation is essential to human health and economic development but energy intensive water treatment technologies are putting severe stress on the environment. In developed countries, one of the major challenges today is the removal of micropollutants, such as illicit drugs, pharmaceuticals, endocrine disruptors or hormones. Found in wastewater at very low concentrations, sometimes at ppb-level, they slowly accumulate in the soil and in ground water, upsetting the ecological balance and eventually finding their way in the human food supply chain, with severe adverse health effects.
Legacy technology comprising the majority of water treatment plants in the UK and other developed countries cannot remove micropollutants, requiring additional treatment steps. Technologies currently being tested all have limitations, in terms of high energy or high capital costs or production of toxic by-products. The urgency of addressing this issue is shown by estimates of multi-billion pound capital investments and £B/year operating costs faced by the UK water industry, to address impending legislation mandating the removal of micropollutants. In fact, the European Water Industry Platform has concluded that the chance of removing micropollutants without significant increases in energy consumption with current technology is 'very low', and that this can be achieved only by 'leapfrogging traditional, polluting and resource-intensive technologies', a view shared by the UK government.
Despite these challenges, the UK has the potential to become a leader in this field, thanks to a thriving water sector, covering the whole supply chain from water utilities (e.g Wessex Water) to treatment plant design (e.g. Modern Water), as well as membrane manufacturing (e.g. Evonik, Micropore). UK water utilities in particular invest more than £10 billion in assets and services each year, employ over 45,000 people, and create 86,000 indirect jobs [1]. This ecosystem places the UK at the top of water-related innovation worldwide but requires significant investment, as indicated by the 2009 Cave Review which highlighted the need to increase the pace and quality of innovation in the water sector to meet better quality standards. The technologies developed in FoAMM will provide a competitive advantage to the whole UK water sector versus competitor nations (Germany, Singapore, USA) that are investing heavily in water innovation. Globally, the water treatment sector was over $200B in 2015 (source: marketresearch.com). This provides a strong opportunity for innovative UK-based technologies to succeed in the global industrial and municipal water treatment market. Maximising these potential impacts requires close interaction and collaboration across the whole water sector value chain as well as a continued dialogue with policymakers and water regulators. A detailed plan to do so is discussed in the pathways to impact document, building on my existing interactions with water utilities and membrane manufacturers and resources available at the University of Bath.

Development of Early Career Researchers
This project will provide advanced training to 7 early career researchers (4 PDRAs + 3 PhDs) in a critical field for the UK research space. All participants will be given the opportunity to participate in the skills training organized by the University of Bath providing early career researchers with non-technical skills to advance their future career. Participation to international conferences will also help the early career researchers in their professional development. It is expected that the most promising candidates will be given the opportunity to enrol in the Faculty of Engineering Fellowship Academy which identifies future research stars to provde dedicated mentoring and opportunities to develop their skills and resume.

[1] www.gov.uk/government/publications/water-and-treated-water/water-and-treated-water