Ozone water treatments treat and purify potable water and industrial water treatment systems. Yet, ozone comes with some downfalls, such as its high cost and maintenance, high reactivity and toxicity, and the ability to form carcinogenic byproducts.
Ozone is a powerful disinfectant, effective over a wide pH range, thus, ozone gas can purify drinking water supplies in water treatment systems, eliminating odors, chlorine, iron, and bacteria.
Before using ozone, you need to understand how it works and the pros and cons.
Ozone is an inorganic molecule and unstable form of pure oxygen with the chemical formula O3. Like chlorine, ozone is a strong oxidizing agent, which can kill bacteria and viruses in water. But, as ozone cannot kill large organisms, the water must also be filtered or an alternative method must be used to eliminate them.
Besides removing bacteria and viruses, ozone is used to oxidize iron and manganese to improve or control the color, taste, and odor.
Ozone water treatment units are installed as a point-of-entry system where ozone mixes with the water being treated. Turbulence and bubbles are created, to ensure the ozone treats as much of the water as possible. The greater the water flow, the greater the turbulence, and therefore, the more effective the ozone water treatment.
While ozone has been used commercially as a powerful oxidizing agent for water treatment systems since 1904, there are some downsides to using ozone to disinfect water that you should know.
Ozone is essential in wastewater and sewage systems that contain carbon-based and organic chemicals and other water pollutants. Even though ozone is more effective than chlorine in eliminating germs and pollutants, there are a few disadvantages that are worth mentioning.
When the ozone dosage is too low, some germs and bacteria may survive, which is why higher ozone concentrations are used. Higher concentrations, however, are more difficult to control, but as ozone is 12 times more soluble in water than chlorine, you can reach the maximum disinfectant concentration more quickly.
Furthermore, ozone breaks down extremely fast, particularly at higher temperatures or in alkaline (high pH) conditions. Also, if the water being treated is rich in organic compounds or total suspended solids (TSS) then ozone will decay more rapidly, as it reacts with these contaminants, leaving a reduced amount of ozone to eliminate germs, which is the sole purpose of ozone water treatment systems. This is why ozone is not used to treat wastewater that contains a high amount of TSS and organic compounds, it’s just not economically suitable.
Continuing from the economic side, ozone is more challenging to produce and deliver than chlorine, making it more costly than chlorination methods.
Ozone water treatments involve plant generators with two electrodes, where the electrical current passes through the electrodes, known as corona discharge. During corona discharge, around 85% of the energy is lost via heat waste, making ozone treatment extremely energy-intensive.
Treating water with ozone is also energy-intensive because it requires high-class equipment, expensive technology, and an operator that knows how to work the complicated system. These all add costs, making ozone water treatments more costly than alternative purification methods.
Ozone is a fantastic disinfectant as it is highly reactive. But with such reactive strength, comes some disadvantages.
Ozone’s reactivity with metals can cause issues in wastewater treatment pipes and containers, therefore corrosion-resistant materials such as stainless steel must be used, which adds to plant construction costs.
Additionally, because ozone is super reactive, it makes it a toxic chemical, so wastewater operators must take extra care and design the plant to ensure that they don’t come into contact with any ozone gas escaping from the water. Again, this adds to the cost of the ozone water treatment system.
Also, because of the high toxicity, ozone levels need to be constantly monitored with an ozone analyzer, these are fairly expensive to buy and replace.
As ozone reacts with organic compounds in the water, it creates byproducts. For example, if the water contains bromide ions, ozone can react to form brominated compounds (like bromate ions/salts), which can cause human cancers. Therefore, treatment operators must control the pH level inside the water or avoid using ozone if the water contains a high level of bromide salts.
What’s more, when chlorine is used in wastewater treatments, there is a residual amount of disinfectant left over, making it easy for operators to keep tabs on how well the water disinfection process was. But, ozone leaves nothing behind; any ozone that doesn’t react with the water contaminants is immediately broken down, leaving nothing to monitor after the disinfection process.
Despite the disadvantages, ozone water treatment has many benefits.
As mentioned, ozone is highly efficient at killing bacteria, and producing ozonated water doesn’t require transportation or storage of dangerous materials as the water is processed on-site.
Ozone water treatments are also used over chlorine disinfection because it produces fewer trihalomethanes (THM) by-products. Additionally, no chlorine or chlorinated disinfection by-products are produced, making dechlorination unnecessary, and simplifying the process.
Ozone water treatment can also assist in filtration by oxidizing sulfates. As ozone disinfects the water, impurities such as iron and manganese are removed.
Another benefit is time. As ozone is 50% stronger than chlorine, less time is required to remove the inorganic and organic impurities than conventional methods such as boiling, filtration, sedimentation, or solar radiation.
Ozone is not the only solution to treating drinking water supplies. To purify water, the following methods can also be used:
Ozone is an efficient way to remove bacteria from water supplies. However, its high reactivity, toxicity, and expensive costs and maintenance are a few reasons why other water purification methods are used.
Before purchasing an ozone water treatment device, determine which contaminants are present. This will help you decide if ozone will be effective for your water or if you should use an alternative system.
If you have any questions about ozone or what water testing kits we have, do not hesitate to contact our world-class team at Atlas Scientific.
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