Ask an Expert: Water reuse evolution

In this month’s feature, BC expert Melanie Holmer shares insights from her recent presentation at the 2022 Water Reuse Europe Conference and Exhibition on Innovations in Water Reuse.

Water reuse is not a new concept.

Dating back to the Bronze Age, humans have used wastewater and stormwater for irrigation of crops. Since that time, reuse has evolved with applications moving beyond agriculture to include non-potable uses such as cooling and toilet flushing and potable uses such as groundwater and reservoir augmentation. Shifting factors such as population growth and climate change impacting water supply have driven this evolution.

Many reuse projects in the private and public sector have been aimed at mitigating the impacts of these shifts. Los Angeles County’s Montebello Forebay Groundwater Recharge Project, which began in 1962, applies recycled water to the spreading grounds to recharge a drinking-water aquifer. The result of this project is a new water supply roughly equivalent to the demands of 250,000 people.

“Urban” water cycles often end with water moving through the community to a wastewater treatment system and back to the river, ocean, or land. Advances in indirect potable reuse and direct potable reuse (DPR) allow water to complete the cycle by including additional treatment to supplement potable water supplies returned back to the community.

The City of Los Angeles’ Hyperion Water Reclamation Plant is a new advanced water purification facility (AWPF) that will provide approximately 1.5 million gallons per day of purified water to Los Angeles World Airports and internal Hyperion Water Reclamation Plant. Source water is primary effluent and AWPF facilities will consist of fine screens, aeration basins, and purified through membrane bioreactors (MBR), reverse osmosis (RO), and ultraviolet-advanced oxidation process (UV-AOP). This facility will serve as a proof of concept for the ultimate expansion of the Hyperion Water Reclamation Plant to an advanced reuse facility.

As public and private entities approach DPR projects, it is important that they consider:

• Constituents of emerging concern (CECs): CECs and their limits vary by location. A project may benefit from understanding presence of CECs and appropriate treatment technologies, evaluating alternative treatments technologies and exploring innovative approaches.
• Enhanced source control: What happens at the source matters in all of the downstream processes. Enhanced source control incorporates increased outreach, education, and monitoring paired with development of individual permit limits or local limits.
• Public perception: The idea of drinking recycled water because of the origin of the source water can lead to challenges with public acceptance of reuse. Education is a key component of changing public perception. Some water utilities are holding events to showcase the safety and drinkability of treated water with sampling of purified water, beer made with purified water, and even gelato made with purified water.
• Regulations: DPR regulations vary by state and are constantly evolving. Staying connected with local regulators and considering future regulatory drivers can steer a DPR project in the right direction.