Ozone-biological activated carbon integrated treatment for removal of precursors of halogenated nitrogenous disinfection by-products

摘要

Pilot-scale tests were performed to reduce the formation of several nitrogenous and carbonaceous disinfection by-products (DBPs) with an integrated ozone and biological activated carbon (_O3-BAC) treatment process following conventional water treatment processes (coagulation-sedimentation-filtration). Relative to the conventional processes alone, O_3-BAC significantly improved the removal of turbidity, dissolved organic carbon, UV254, NH+ and dissolved organic nitrogen from 98-99%, 58-72%, 31-53%, 16-93% and 35-74%, respectively, and enhanced the removal efficiency of the precursors for the measured DBPs. The conventional process was almost ineffective in removing the precursors of trichloroni-tromethane (TCNM) and dichloroacetamide (DCAcAm). Ozonation could not substantially reduce the formation of DCAcAm, and actually increased the formation potential of TCNM; it chemically altered the molecular structures of the precursors and increased the biodegradability of N-containing organic compounds. Consequently, the subsequent BAC filtration substantially reduced the formation of the both TCNM and DCAcAm, thus highlighting a synergistic effect of O_3 and BAC. Additionally, O_3-BAC was effective at controlling the formation of the total organic halogen, which can be considered as an indicator of the formation of unidentified DBPs.