By Melanie Holmer and Adam Zacheis, Brown and Caldwell

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 have driven this evolution.

Many water 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 meet the demands of 250,000 people.

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

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 internally to the Hyperion Water Reclamation Plant itself. AWPF facilities will use fine screens, aeration basins, and will purify source water which is primary effluent 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 projects to further the evolution of water reuse, it is important that they consider:

• Constituents of emerging concern (CECs): CEC management strategies may vary by location. A project may benefit from understanding the 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 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.

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Melanie Holmer is the Water Reuse National Practice Lead for Brown and Caldwell. She is based in California and has over 20 years of experience in the strategic planning, design, and construction of major water, wastewater, and water reuse projects for a total treatment capacity of over 1 billion gallons per day. Connect with Melanie on LinkedIn.

Adam Zacheis is Brown and Caldwell’s Water Reuse Area Practice Leader for Southern California. He is based in Los Angeles and has more than 25 years of experience in alternative water uses and developing resilient water portfolios. His background includes process engineering, pilot plant research, membrane water treatment plant design, advanced treatment facility design, and advanced oxidation technologies application. Connect with Adam on LinkedIn.