Ozone Wastewater Disinfection

Ozone Municipal Wastewater Disinfection

Ozone disinfection is generally used at medium to large sized plants after at least secondary treatment. In addition to disinfection, another common use for ozone in wastewater treatment is odor control. Ozone disinfection is the least used method in the US although this technology has been widely accepted in Europe for decades.

Ozone treatment has the ability to achieve higher levels of disinfection than either chlorine or UV although the costs can be higher. Ozone is used primarily in special cases where alternatives are not effective. Some of the reasons why include:

• Ozone is more effective than chlorine in destroying viruses and bacteria.
• The ozonation process utilizes a short contact time (approximately 10 to 30 minutes).
• There are no harmful residuals that need to be removed after ozonation because ozone decomposes rapidly.
• After ozonation, there is no regrowth of microorganisms, except for those protected by the particulates in the wastewater stream.
• Ozone is generated on-site, and thus, there are fewer safety problems associated with shipping and handling.
• Ozonation elevates the dissolved oxygen (DO) concentration of the effluent. The increase in DO can eliminate the need for reaeration and also raise the level of DO in the receiving stream.

The following link is an EPA Ozone Wastewater Disinfection fact sheet.