Filtering through the Results: The impact of TOC and Filter Technology on Ozone Disinfection Performance for Recycled Water Applications

A benefit of ozonation is that it can provide both disinfection and pollutant destruction for recycled water applications. The use of ozone was approved by California as an alternative disinfection technology for the production of recycled water in 2008 based on extensive validation testing. Since 2008, several full-scale ozone systems have been built, commissioned, and spot-check bioassayed to verify the ozone system disinfection performance. In addition to the original validation several other ozone disinfection systems have undergone validation testing at locations with varying water quality. Ozone is a very powerful oxidant that can preferentially react with organic carbon and nitrite before inactivating other pathogens. This was confirmed during the studies. Although the CT concept continues to be a good tool for system design and control, the use of O3/(TOC+NO2-) ratios for design/operation of ozone systems is a promising method of system control that more effectively describes ozone system performance.