Ozone technology has been used for the past two decades or more. It is, however, only now that its use in wastewater treatment has been recognized.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/ozone-wastewater-treatment
[2] http://admin.indiaenvironmentportal.org.in/category/author/v-baratharaj
[3] http://admin.indiaenvironmentportal.org.in/category/journal/everything-about-water
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sewage-treatment-technology
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/ozone
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/science-and-technology