Although water makes up about 70 percent of the Earth’s surface, the small fraction that’s fresh is precious.
That’s why CSULB Professors Matthew Becker and Stephen Mezyk are so interested in H2O and why the Orange County Water District (OCWD) is among the public agencies who tap into their expertise for research projects.
Becker is the Conrey Endowed Chair in Hydrogeology in the Geological Sciences Department and cares about where water comes and goes, while Mezyk’s RadKEM Lab in the Chemistry and Biochemistry Department studies wastewater remediation.
Despite being a semi-arid desert on the surface, the Los Angeles Basin sits atop several aquifers where water collects underground.
“The way [water agencies] see groundwater in the L.A. Basin and in Orange County is basically as a big storage tank. It’s a resource to be tapped, but also recharged and refilled,” Becker said. “They divert water from rivers into these recharge basins, which also are called spreading basins, or they’ll buy water from the Colorado River and percolate it down into the aquifer to be drawn out as drinking water months or years later.”
It’s easier said than done, Becker explained. “For example, in Orange County, if you put a recharge basin closer to the coast, you’ll find that there’s a lot of clay between the surface and the aquifer and it will never percolate down in a reasonable amount of time, so all the recharge basins are a little farther north.”
Once the right location is found, ongoing maintenance becomes important, which is one reason OCWD commissioned Becker’s lab for assistance. “The instrumentation that we’ve developed allows them to monitor the rate of infiltration in the basin,” Becker said. “They’ve been pretty happy with what we’ve been able to do in a pilot study, so now we’re in the process of helping them install a larger system. Our pilot study was in a small basin and now we’re doing a larger basin, which is why we’re digging a mile of trench.”
Becker has been working with OCWD Recharge Planning Manager Adam Hutchinson. “Partnering with Dr. Matt Becker and the graduate students on developing innovative ways to better understand how our recharge basins perform has been a positive experience with rewarding outcomes,” Hutchinson said. “Not only have we obtained useful information, but the research has been published in groundwater journals, allowing others engaged in designing, operating and maintaining recharge facilities to benefit.”
Becker and his students laid fiber-optic cable and sensors in a basin alongside the Santa Ana River in Anaheim. Since then, they found that the Orange County spreading basins weren’t behaving in the way standard models predict.
Agencies typically create broad, shallow basins with less concern over water depth, Becker explained. “What we found was that the percolation rate was going up and down very closely with the amount of water in the basin. As they drained the basin and it went down to a foot, the rate of water percolation decreased, and as the depth went up, the percolation rate increased.”
Becker’s experimental fiber-optic sensors measure heat rather than water depth, he said. Water warms during the day and and cools during the night, so “The peak of the warmest time of the day, say a meter below the basin, is three hours later than the peak at the surface. We can calculate the rate of percolation by watching how fast those temperatures propagate down.”
Their project is producing helpful data. For instance, the studies can determine where and when silt clogging is occurring and whether silt removal would increase recharge and perhaps aid agencies in more efficiently operating and maintaining the basins.
Clean and Clear
For Mezyk, “One of our major research interests is the chemistry that happens at OCWD in their processing of wastewater, which is better than pretty much anyone else in the country.”
Orange County water goes through an extensive series of cleanup procedures starting with the Orange County Sanitation District, which does several initial water treatments. The secondary treated wastewater is then sent to OCWD for three additional purification steps using microfiltration, reverse osmosis and finally an advanced oxidation process using ultraviolet light with hydrogen peroxide (UV/H2O2)—one of OCWD’s most important innovations that destroys trace organics before the water is recharged into deep aquifers.
OCWD operates the world’s largest indirect potable water treatment facility known as the Groundwater Replenishment System (GWRS), which produces 70 million gallons a day of clean water that is used for groundwater recharge and to hold back seawater from contaminating the aquifer.
“We are examining the chemistry behind the advanced oxidation process to see how it is really working,” Mezyk explained. “For example, one of the chemicals added during the wastewater treatment is disinfectant chlorine to remove microbial activity. Our group is investigating the chemical reactions that these disinfectants undergo, particularly the products of their oxidation. We’ve been working with them to understand how certain anthropogenic contaminants get through all this magnificent treatment that they do and recently how other disinfection by-products are produced in the disinfection treatment.”
Collaborating with OCWD chemist Ken Ishida, Mezyk continued, “We’re working together to understand the chemistry involved. He’s interested in the overall large-scale wastewater treatment, and I’m working to support him on a much smaller scale by explaining some of the chemistry occurring in his treatment systems.”
Water treatment chemistry on such a tremendous volume can be both challenging and expensive, so Mezyk and colleagues from OCWD and elsewhere are looking at possible ways of adjusting the chemistry to be safe, efficient and more cost-effective.
Mezyk is taking advantage of CSULB’s Institute for Integrated Research in Materials, Environments, and Society (IIRMES), a state-of-the-art campus lab that contains advanced analytical equipment. “OCWD has an excellent analytical lab,” Mezyk said, but IIRMES’ quality, proximity and cost effectiveness considerably benefit his work.
One of Mezyk’s major research directions is an issue facing water agencies around the globe—dealing with chemicals that can’t yet be eliminated including medications that people excrete or dump into toilets.
“What we’re investigating is how to destroy antibiotics and steroids in wastewater, and how much energy and cost is required to use these advanced oxidation processes,” he said. “We don’t want to expose environmental bacteria to antibiotics and we don’t want to have trace amounts of steroids or even the mimics like bisphenol A [a chemical known as BPA that softens plastics] in our waterways or in our drinking water. The idea is to get rid of them before we release all this water back.”
All these projects are beneficial collaborations between CSULB and OCWD. “The chemical dynamics of OCWD’s UV/H2O2 advanced oxidation process are quite complex. Professor Mezyk’s undergraduate and graduate students have been instrumental in elucidating some of the intricate details of the oxidation process,” Ishida said.
“Working with them has been amazingly positive for us because we actually have real world applicability literally 20 minutes down the road,” Mezyk concurred.