Ozone treatment of water in Oregon in its second year

Kelly J. Kaczala

        Oregon’s Harmful Algal Bloom infrastructure improvement project was completed last year. It ensures that microcystin, a toxin released from Harmful Algal Blooms (HABs), does not get into the water supply.
      The $15 million project is an upgrade to the city’s water treatment plant with the installation of ozone equipment.
        The ozone treatment of water is very effective in treating microcystin, the toxic algae that caused a tap water ban in Toledo in 2014. Ozone treatment also improves disinfection and treatment of other organics, as well as lower disinfection byproducts from chlorination, which has the added benefit of improving the taste of drinking water for Oregon water customers.
        “We’ve had ozone treatment now for two years,” said Oregon Public Service Director Paul Roman. “We’re well prepared for anything. I feel we have every tool in the toolbox that you can have for any surface water treatment plant. It’s a disgrace when you see the lake’s condition. But our drinking water  is going to be very safe.”
Fewer chemicals
        The treatment process consists of the application of ozone to settled water and modifying filters for Biologic Active Filtration (BAF). Ozone breaks up contaminants into very small particles, which are so small that the city’s filtration system was not enough to properly remove those contaminants from the water. BAF, which goes hand in hand with ozone, is the use of natural microorganisms that will remove the contaminants and further oxidize and remove material from the water.
        Ozone treatment also lowers Trihalomethanes (TMHs), a byproduct of chlorine, which is used to disinfect the water. Some studies have shown TMHs, in higher concentrations, can cause adverse health effects, including cancer.
        “Ozone is extremely powerful in terms of oxidizing or destroying toxins. For chlorine to bring microcystin to its half life, it takes 12 hours. But for ozone, it’s .08 seconds. That’s how powerful it is,” said Roman.
        “It’s working for our community and working for our future,” Oregon Administrator Mike Beazley said of ozone treatment. “It was worth the investment. Algae continues to be a considerable problem for our lake. But it’s no longer a significant challenge for our drinking water. We feel very good about our water quality. Ozone is the best practice. We feel good we headed in that direction. It really took what was a significant challenge to us during the algae season and put it in the past.”
        The upgrade was funded by a grant from the Ohio Public Works Commission (OPWC), and a 0 percent loan through the Ohio EPA from its Water Supply Revolving Loan Account Fund. The loan will be paid over 20 years with a capital improvement charge that will be included in consumers’ water bills.
        Oregon was not affected by the microcystin that shut down Toledo’s tap water supply. But Oregon’s intake crib is located in Lake Erie, about 16 feet deep and 1.5 miles from shore. It draws millions of gallons of water out of the lake for use by Oregon residents and surrounding communities that are Oregon water customers. The intake crib is not far from Toledo’s. Oregon has taken a very proactive approach to improving water quality in the last several years.
        “We’ve installed a lot of wetlands at the downstream end of a lot of our drainage systems before it discharges into the lake,” said Roman. “The wetlands try to slow down the flow. Plants in the wetlands will uptake nutrients so that the nutrients are no longer going straight out to the lake. If you have e.coli  going through a very shallow area at a slow rate, the sun will destroy it before it goes anywhere. Nutrients connect to sediment. If you can get sediment to drop out, nutrients will do the same. That’s the key.”
        Oregon has also expanded its wet weather treatment capacity at its sanitary sewer treatment plant to have fewer episodes of sanitary sewer overflows into the lake.
        “We’ve increased our wet weather capacity from 24 million gallons per day to 36 gallons per day. We can handle a lot more now. And at the same time, we’re trying to reduce I & I (inflow and infiltration) from getting into our sanitary sewers.”
        The city has spent about $15 million to line the sewers,” he said.
        “Along with the wet weather treatment capacity increase, which cost $15 million, we’ve put a total of $30 million into our wastewater system,” said Roman.
        Tree roots can cause the joints of sewer lines to open up. Ground water will then infiltrate the joints.
        “If you line the pipes, you’re almost getting rid of all this groundwater infiltration coming through the joints of the sanitary pipes,” explained Roman.
         “But we’ve done a lot in terms of dealing with our wet weather and sewage. At the same time, we’ve added ozone. I feel like we’re in as good of shape as ever before.”


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