As California enters the sixth year of its historic drought, a researcher's award to explore water reuse technologies for drinking water supplies comes at a propitious time for the water-starved state.
The $300,000 grant, made by the National Science Foundation to the University of California, Riverside’s Bourns College of Engineering, will support the work of Haizhou Liu, assistant professor of UCR's chemical and environmental engineering.
Liu’s research is partnered with the Orange County Water District (OCWD), which operates the Groundwater Replenishment System (GWRS), the world’s largest water purification system for indirect potable reuse.
Liu will collaborate with Kenneth Ishida, principal scientist at OCWD, to investigate the addition of chloramines—a group of compounds that are generated when chlorine and ammonia are mixed —to a treatment step that currently uses hydrogen peroxide and ultraviolet (UV) light.
OCWD manages and protects the Orange County Groundwater Basin, which supplies 75% of the potable water supply for 2.4 million people in north and central Orange County. A joint project of OCWD and the Orange County Sanitation District, the GWRS purifies treated wastewater to produce 100 million gallons of high-quality drinking water every day, enough water for 850,000 residents annually.
CREATING ULTRA-PURE WATER FOR HUMAN CONSUMPTION
The researchers believe the alternative process will improve water quality and lower treatment costs, ultimately alleviating water shortage concerns in one of the country's most drought-stricken areas.
While all wastewater must be treated before being released back into the environment, treated wastewater that is purified for potable use must undergo a stringent purification process along with rigorous monitoring and testing. As noted by Sarah Nightingale, the GWRS purifies wastewater using a three‐step advanced process consisting of microfiltration, reverse osmosis, and ultraviolet (UV) light with hydrogen peroxide. The result is ultra-pure water that meets or exceeds state and federal drinking water standards.
Liu said that like hydrogen peroxide, chloramines can be activated by UV light to degrade trace organic contaminants in wastewater in a reaction called an advanced oxidation process (AOP). While chloramines are frequently used in other stages of water purification processes like disinfection, they haven't been studied as oxidants in the presence of UV light, per a UCR article.
“So far, little is known about the optimization of chloramine photolysis for water reuse applications, but the results of early studies in my lab suggest a very beneficial reaction that could be relevant to many water utilities,” Liu tells Nightingale. “In particular, we found that chloramines can generate highly reactive chemicals upon UV photolysis, but this only happens under certain chemical conditions.”
Liu said the university-industry collaboration serves as a model to develop efficient, cost-effective and sustainable water reuse technologies that will improve U.S. global competitiveness in this field.
“If successful, this project can both save photon energy cost at treatment facilities and improve the quality of recycled water for drinking purposes. Our ultimate goal in developing this technology is to alleviate the drought impact and protect human health,” Liu says.
Unfortunately, the impact of the drought appears far from over, reports the LA Times. In 2015 alone, the drought's economic cost was pegged at $2.7 billion.
Compared with that economic devastation, a grant in the amount of $300,000 may seem a proverbial drop in the bucket, but one that has huge, and necessary, implications.