Ozone Treatment (COMING SPRING 2021)

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​What is the long-term solution for removing cyanotoxins?

The City of Salem is installing a state-of-the-art ozone treatment system to remove cyanotoxins. Ozone is one of the strongest disinfectants used to treat water – it is even stronger than chlorine. Ozone also makes our water crystal clear, improves the taste, and can remove odors. Once in operation in spring 2021, ozone will be our robust, long-term insurance policy against cyanotoxins.

What are the benefits of ozone?

Ozone treatment offers many benefits:

Destroys cyanotoxins

Makes it easier to ensure safe drinking water

Works well with the other treatment steps on Geren Island

Produces good tasting water, year-round

Reduces how much chlorine is needed

No ozone is left in the water after it has done its job

How does ozone work?

Step 1.

Oxygen Supply:  Ozone (O3) is made from oxygen (O2). We are using super-cooled liquid oxygen. The liquid oxygen is first warmed and converted to oxygen gas. The oxygen gas is then sent to an "ozone generator."

 

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Liquid Oxygen Supply Step 1

Step 2:

Ozone Generation:  The ozone generator uses an electric charge to turn oxygen gas (O2) into ozone gas (O3). Once formed, ozone gas moves to a "contactor" chamber where it dissolves into and begins to clean our drinking water.

Ozone Chamber Step 2

​Step 3

Ozone Injection and Contactor: In the contactor chamber, ozone gas (O3) dissolves into the water. Here, it destroys cyanotoxins (if they are there) and breaks down any remaining materials that may affect the taste or smell of the water.

Step 4

Dissolved Ozone:  Under normal operating conditions all of the dissolved ozone is used in the treatment process.  If all the dissolved ozone (O3) isn't used up, it will go through a process to turn it back into oxygen gas  (O2) before it is discharged back into the atmosphere. 

 

​How will ozone integrate into the existing Geren Island Water Treatment Plant?  [See Figure 2]

We have a multi-step approach to destroying cyanotoxins. The ozone contact chamber will be located downstream of the existing roughing filter. The roughing filter removes cyanobacteria (the primary source of cyanotoxins). Any remaining cyanotoxins will be destroyed by ozone treatment. Water will then be cleaned in the slow sand filters and chlorinated.

What else are we doing to ensure a safe and sustainable water supply moving forward?

We are investing in a groundwater system on the Geren Island Water Treatment Plant. Groundwater wells can provide another source of water that is protected from cyanobacteria and storm events that impact the North Santiam River.

Figure 2