A recent IWA webinar provided insights into new developments on water reuse in the USA. The Source explains how new regulations in California are stimulating advancements that will benefit other regions in the USA and could provide valuable knowledge for water reuse projects around the world.
California has the largest economy in the USA. Demand for water in the state is high, with consumers and businesses demanding high volumes of water. Home to one of the most productive agricultural regions on Earth, the aridification of California has become a particular concern. To help combat this trend, water reuse programmes, which began in the 1970s, have been expanded. Now, this relatively mature water reuse market is helping to pave the way for expansion of the technology across the USA.
Recent advocacy led by the WateReuse Association has secured $1 billion for water recycling as part of the Infrastructure Investment and Jobs Act of 2021 (IIJA). The US Department of Interior’s (DOI’s) Bureau of Reclamation has begun to release these funds, beginning with $550 million for the Title XVI Water Reuse Grants Program. This programme identifies and investigates opportunities to reclaim and reuse wastewaters in regions with impaired ground and surface water in the 17 Western States in the USA and Hawaii.
The WateReuse Association’s executive director, Patricia Sinicropi, has applauded the DOI’s swift dissemination of funds, stating that: “Investment in water reuse is already generating economic, environmental, and public health dividends around the country.” She believes that these new federal investments will help more communities secure their water future.
Currently, 43 of the 50 states that make up the USA, practise water reuse. With the notable exception of Big Spring in Texas, almost all water reuse in the USA is either for non-potable purposes or is indirect potable reuse (IPR), where treated wastewater is reintroduced into an environmental water body, before re-abstraction for potable purposes. As water scarcity worsens, Californian water planners are now turning to the more contentious process of direct potable reuse (DPR), with new DPR regulations due in 2023. The Californian DPR debate was recently discussed in The Source.
Examining the latest developments on water reuse in the USA, a recent IWA webinar considered how experience in California is influencing research and advancements in water reuse. This knowledge is being adapted to respond to different drivers for water reuse across the USA and can provide lessons for existing reuse projects around the world, as well as for those countries in the early stages of the reuse journey.
The research base
Water reuse can attract social and political attention, and so, for good reason, the initial stages of a reuse project typically involve a significant amount of research. Traditionally, projects have focused on treatment processes to remove pathogens and other contaminants. However, research programmes are now diversifying in response to the need to apply reuse techniques under different scenarios, serving different needs, and creating resilience to the extremes of weather associated with climate change.
Julie Minton, research unit leader at the Water Research Foundation (WRF), explained in the webinar how research is maturing by outlining the Foundation’s Core Priority Research Program themes:
- Resource efficiency and recovery (circular economy)
- Treatment optimisation
- Resilient infrastructure (to overcome infrastructure and water quality challenges)
- Utility operations and management (to support financially sustainable, optimised, and forward-thinking utilities)
- Healthy communities and environment (improved watershed resilience, enhanced community resilience, public health, and the environment)
These research programmes are intended to advance both potable and non-potable reuse to pave the way for the world to understand better the obstacles to reuse and overcome those barriers. The scale of funding within the foundation ($6.2 million in 2022) demonstrates the commitment to continued research.
Direct potable reuse without reverse osmosis
Non-reverse osmosis (RO) alternatives are now a hot topic across the USA and some states are leading the charge on alternative treatment approaches for DPR, with new demonstration facilities working out the detailed nuances of how reuse can work without RO.
RO has long been the core process in reuse treatment trains. Dr Jörg Drewes , chair of urban water systems engineering at the Technical University of Munich, explained that treatment trains are usually bespoke, and while RO has typically been seen as the ‘Gold Standard’ for treatment, “the basic and shared principle across all reuse projects is to have multiple barriers to address Contaminants of Emerging Concern (CECs)”.
In her presentation, Eva Steinle-Darling, from Carollo Engineers, highlighted the long history of indirect reuse in the USA using RO, and presented examples of direct potable reuse projects that are under way to develop “alternative, cheaper, non-brine generating processes that don’t require an ocean outfall and which will open up the potential for potable reuse for inland communities”.
At the core, most of these employ a Carbon-Based Advanced Treatment (CBAT) approach, essentially consisting of ozone, biological activated carbon (BAC) for filtration, and then granulated activated carbon (GAC), the absorptive polishing component. Disinfection processes are then added, either UV or chlorination depending on the required output quality. Steinle-Darling recognises concerns over PFAS (perfluoroalkyl chemicals) and clarified that, in the CBAT approach, PFAS removal is achieved successfully within the GAC component.
Reuse projects are emerging across the eastern states and the water-rich Pacific Northwest, driven not just by water scarcity, but by increasingly stringent numerical nutrient discharge limits and restrictions on wastewater discharges, with implications for the processes and regulatory frameworks that can be adopted.
In California, the policy and legislative approach to reuse has tended towards regulating treatment technologies – for example, specifying treatment types to use. Jennifer West, managing director of the WateReuse Association California, explained that: “California has demanded RO to reach a very stringent Total Organic Compound (TOC) target that exceeds human health requirements.” Her concern is that regulations could inadvertently suppress innovative, new technologies.
The maturing water reuse sector in the USA is providing valuable lessons for others preparing or implementing water reuse. Treatment trains are typically bespoke, considering influent quality and the intended recipients. There is no single approach and no blueprint to follow to develop guidance, frameworks or regulations. In the USA, each state is developing its own approaches. However, the webinar experts agreed that it is extremely beneficial to develop a coordinated national (or regional) research strategy to share knowledge and drive innovation.
Funding models for water services infrastructure differ widely, but the USA shows that without regulations development, well-managed public perception, and funding, reuse projects don’t move forward.
Many of the existing reuse projects in California were made possible through General Obligation Bond Initiatives that made funding available specifically for recycled water (approved in 2015). This made low interest loans available for water reuse. In addition, the WateReuse Association and its partners have been successful in gaining Federal Infrastructure funding for recycled water.
Dr Drewes explained that in some areas of the world, such as Australia and Singapore, there is already a lot of government support to establish reuse. Elsewhere, including Europe, countries are still following a steep learning curve, and are in the process of identifying needs and treatment options. Drewes concludes that it is important to learn how other countries, such as the USA, have financed their projects and to engage with stakeholders to design a successful financing scheme.
Public perception can be the most damaging or enabling component for reuse. Inevitably people ask questions about why reuse is needed. The panellists agreed that success hangs on the answers to these questions being crystal clear. Minton acknowledged that community engagement is vital, saying: “Utilities now understand that they don’t need to just invest in the technology and the operations, they also need to invest in education, outreach, and building education centres.”
West summarised how public perception has changed over the past 20 years, concluding: “Initially, legislatures were concerned about using recycled water for irrigation purposes”, but now public policy and society “have embraced the notion of potable reuse. Established projects like the Orange County Groundwater Replenishment System and outreach programmes, propelled by the mega-drought issues, have helped people embrace the value of water concept.”
View this webinar at: iwa-network.org/learn/water-reuse-in-the-united-states-a-trend-on-the-rise
See ‘Development of direct potable reuse regulations in California’, www.thesourcemagazine.org/development-of-direct-potable-reuse-regulations-in-california
Carbon-Based Advanced Treatment direct potable reuse projects in several states since 2017
- Florida (2017): the PureALTA demonstration project won a silver IWA Project Innovation Award using ultrafiltration as a pathogen barrier, GAC as an absorptive barrier, and UV with AOP for additional disinfection, which effectively replaces the need for RO.
- Virginia (2018): SWIFT Groundwater Augmentation, demonstrating the safe production of 4Mld recycled water without RO, with the aim of scaling this to 450Mld.
- Colorado (2021): leading the development of mobile DPR treatment, this project adopted CBAT core processes with UV and chlorine, with the processes installed on the back of a mobile trailer.
- Utah (2022): the ‘Pure South Jordan’ five-year demonstration project has just launched and aims to provide another step forward in the advancement of non-RO water reuse in an area confronting brine disposal issues.
These states have recognised that they can get to the same water quality outcome and meet their bespoke needs without necessarily employing RO.