Comparison of O3-BAC and GAC for removing micropollutants from drinking water

Studied was the comparison of ozone-biological activated carbon (O₃-BAC) and granular activated carbon (GAC) processes for advanced drinking water treatment. The effects by O₃-BAC and GAC were evaluated based on the removal of the indexes including COD_Mn, UV₂₅₄, TOC, BDOC, NH₄⁺-N, NO₃^--N and NO₂^--N. The results showed that the treatment effect by O₃-BAC was better than that by GAC alone. When ozone dose was at its optimal level 2.0mg/L, the removal efficiencies of COD_Mn, UV₂₅₄ and TOC by O₃-BAC were 15.1%, 17.4% and 16.2% respectively higher than that by GAC alone. Furthermore, BDOC removal by O₃-BAC process was four times as much as that by GAC process. The NH₄⁺-N and NO₂^--N of O₃-BAC effluent were both lower than that of GAC alone. Ozone increased the lower molecule weight organic compounds capable of being easily adsorbed by activated carbon and improved the biodegradability of the organic matters in the water so as to strengthen the biological treatment capability for organic pollutants by the subsequent treatment units.