| Ozone has been shown to be very effective in the transformation of several CECs that escape the wastewater treatment process, but there is concern whether toxic transformation products are formed. Two parallel biofilter columns with granular activated carbon (GAC) and filter sand following a pilot scale ozone unit to treat secondary municipal wastewater treatment plant effluent were studied. The biologically activated carbon (BAC) biofilter outperformed the sand biofilter in terms of DOC, DO and UV254 removal. In addition, GAC supported more biological activity than sand media. Genotoxicity results show reduced wastewater genotoxicity following ozonation and further reduction following BAC and sand biofiltration. However, bacterial re-growth did occur in both biofilters following ozonation and needs to be taken into consideration when implementing ozone-biofiltration units. |
