Find out more below about our third WRE Conference and Exhibition Speakers and their talks for the sixth session Water Reuse for Potable Applications:
Mihaela Stefan
Senior Research Scientist, Trojan Technologies, Canada
Dr Mihaela Stefan is a Senior Research Scientist at Trojan Technologies in London, Ontario, Canada. She has a Ph.D. degree in Photochemistry and Chemical Kinetics, and 30 years of experience in fundamental science and application of UV light-induced advanced oxidation processes for micropollutant treatment in water sources. Dr. Stefan was involved in piloting and full-scale implementation of UV/AOPs at water utilities, most recently at potable water reuse sites. She authors book chapters and publications in peer-reviewed journals. She is the Editor of the book “Advanced Oxidation Processes for Water Treatment: Fundamentals and Applications” (IWA Publishing, London, UK).
Keynote: The journey of UV/Chlorine AOP from fundamental science to successful full-scale implementation in IPR projects in California
Chlorine chemistry and photochemistry have been studied extensively, but the combination of UV radiation and free chlorine as an advanced oxidation process (AOP) for contaminant destruction in water sources has been explored only in recent years. At wastewater reclamation utilities for the purpose of potable reuse, the UV/Chlorine AOP is implemented after the reverse osmosis (RO) filtration step. Typically, the RO permeate (ROP) contains free ammonia, chloramines, bicarbonate, nitrate, and very low levels of organics. All these parameters play important roles in UV/Chlorine process efficiency. For example, breakpoint reactions occur between free chlorine, ammonia and chloramines, which change the initial ROP quality characteristics, among which, the UV transmittance and the water background “demand“ for reactive radical species. Chloramines absorb the UV radiation and photolyze inside the UV system. They are also the major scavengers of reactive radical species generated in the system. Understanding and predicting chlorine chemistry in the ROP, photochemistry of all chlorine species and subsequent radical and molecular reactions inside the UV reactor are paramount for accurate UV equipment sizing and UV/Chlorine performance prediction and control in water reuse projects. The fundamental science, mechanistic-kinetic model, and case studies of full-scale UV/Chlorine AOP for potable reuse will be discussed.
Varsha Wylie
Principal Process Engineer, Southern Water
Varsha Wylie is a Principal Process Engineer with Southern Water and has approximately 23 years of experience in the design and construction of water and wastewater treatment plants. Varsha has worked extensively on UK projects for several water companies. Before joining Southern Water, Varsha spent 2 years, managing the delivery of design projects in Pune (India) for international water utilities based in Australia, New Zealand, the Middle East and the UK. She also spent 3 years in Dallas (Texas, USA) as a client service manager and technical delivery lead working on projects for North Texas water utility clients. Varsha received her MSc in Environmental Technology from the University of Manchester, and she is a Chartered Chemical Engineer with the Institution of Chemical Engineers. Over the last 7 years, Varsha has worked in the Water Process team at Southern Water and is currently leading the process design work for four water recycling plants proposed in Hampshire, the Isle of Wight, Kent and Sussex. She is also the chairperson of the All Company Working Group on Water Recycling, set up by the regulators, that aims to produce a guidance document on water recycling for the UK water industry.
Presentation: Southern Water’s new approach to augmenting raw water supply in Hampshire
Under Section 20 of the Water Resources Act 1991, an agreement between the UK Environment Agency (EA) and the UK water utility Southern Water (SW) was finalised outlining a package of monitoring, mitigation, and Habitats Regulations compensation measures in the Hampshire Area. Southern Water committed to use ‘all best endeavours’ to ensure delivery of the Long-Term Water Resources Scheme described in the final Water Resources Management Plan 2019 (WRMP). As such, Southern Water has been investigating and promoting the strategic alternative namely water recycling, which has not been widely deployed in the UK. Developing this scheme has necessitated a collaborative approach between water companies and regulators to promote expedient decision-making. Given the nature of the source water used in a planned water recycling approach for raw water augmentation, water companies have invested significant time and financial resource to collect data to inform both the drinking water safety planning process and customer engagement to ensure the success of these schemes. Running pilot trials have been shown to be primordial to engage with key stakeholders and validating the selected multi-barrier treatment process. SW has run a full-advanced treatment pilot to demonstrate the suitability of the reference design proposed to treat source water from Budds Farm, SW’s largest wastewater treatment plant.
Jordi Molist
Director of Water Supply, Catalan Water Agency
Jordi Molist is a civil engineer who has been working in public water management for twenty years. He currently heads the Water Supply area at the Catalan Water Agency. His responsibilities include the planning and administration of the water resources of the Catalonian River Basin, including the Greater Barcelona area, as well as the promotion of new water supply and water reuse infrastructures.
Presentation: Indirect potable reuse in Barcelona
Catalonia is currently experiencing the most severe drought on record over de last century. Since November 2022, the water supply for the Greater Barcelona Area has relied on an indirect potable reuse system. Under this scheme, reclaimed water is discharged into the Llobregat River just eight kilometres upstream from the drinking Barcelona water treatment plant. The dilution ratio has been progressively increased and now stands at approximately 1:1, with an equal mix of reclaimed water and natural river flow. The success of the Llobregat River project is attributed to a comprehensive risk assessment conducted beforehand and to the early involvement of multiple stakeholders. Drawing from these lessons, as well as from advancements in non-target screening analytical techniques, the Catalan Water Agency has initiated the construction of two new indirect potable reuse projects close to Barcelona, and additional ones are planned or under consideration.
