WCW26

Twenty-five years ago, the US National Research Council considered potable reuse a “solution of last resort.” Today, it is a mainstream water supply option in the western United States, and is increasingly being implemented in eastern States. In Canada, water reuse has been practiced since the 1970’s, first in the Okanagan Valley as a means of addressing nutrient loading; today, discussions regarding water reuse have re-emerged in response to modern water challenges. Alberta’s upcoming Water Amendment Act (Bill 7) and regional initiatives including the City of Calgary’s Water Scarcity Roadmap and Water Reuse Assessment signal a renewed national focus on potable reuse at home.  

Treatment technology selection is a careful balance of regulatory preference, source water quality, and public perception. The rapid implementation of reuse technologies in the United States has been enabled by extensive academic research, public engagement efforts, and demonstration facilities ranging from proof-of-concept trailers, to simple outdoor pilots, to “museum-quality” permanent installations.

Historically, potable reuse facilities relied on reverse osmosis- based advanced treatment (RBAT), which is a codified requirement in some US states (notably California). As potable reuse expands into new markets, however, carbon-based advanced treatment (CBAT) has emerged as an equivalent treatment approach, with reduced cost and operational complexity. This shift has been the subject of extensive research through the Water Research Foundation, beginning with Project #1695 (Equivalency of Advanced Treatment Trains for Potable Reuse) published in 2016, followed by numerous studies exploring treatment performance, process innovations and optimization, monitoring, and validation. Early full-scale Indirect Potable Reuse (IPR) projects, where reclaimed water is introduced into an environmental buffer (reservoir or groundwater) use CBAT, including a facility on the Upper Occoquan (VA), followed by Gwinnett County (GA), and now at Hampton Roads (VA). This enables communities to pursue potable reuse without the cost of RO membranes, or needing to dispose of RO concentrate.

Now, CBAT projects push utilities towards the last frontier: Direct Potable Reuse (DPR), where purified recycled water is introduced directly back into the drinking water supply without first passing through an environmental buffer. Starting in 2017 with the international award-winning pureALTA DPR demonstration project in Altamonte Springs, Florida, and followed thereafter by similar projects in Florida (One Water Polk), Utah (Pure SoJo), and Tennessee (multiple), CBAT is being established as a viable and cost-effective approach to DPR where desalination is not required.

This presentation will begin with an overview of potable reuse technologies and their implementation across Canada and the United States. It will then discuss our understanding of CBAT performance, starting with results from WRF 1695 and subsequent research, continuing to case studies from the CBAT DPR demonstration facilities listed above, and a sneak peek at the most recent XBAT testing data. Finally, the presentation will conclude with a brief overview of a customizable CBAT process model based on all of these data, allowing utilities to explore options for potable reuse, including what specific CBAT configurations may be best for them.