Formation of Chlorophenols and Related Compounds in Natural and Technical Chlorination Processes

Surface water was halogenated by the addition of: (i) chloroperoxidase, hydrogen peroxide and chloride; (ii) hydrogen peroxide and chloride or bromide; (iii) hypochlorite. Analysis of adsorbable organic halogen (AOX), halogenated phenols and purgeable organic compounds showed that reactions (i) and (ii) produced almost the same halogenated compounds. It was also shown that active chlorine occurred as an intermedi-ate in reaction (i). Reaction (ii) implied a marked halogenation only after the addition of bromide, and this reaction was enhanced by a low pH. Existing evidence that 2,4,6-trichlorophenol may be naturally produced was strengthened. Some evidence was also obtained indicating that enzyme-mediated reactions may contribute to the natural formation of dibenzo-p-dioxins.