Mechanism study of the coagulant impact on mutagenic activity in water

Both gas chromatography/mass spectrometer (GC/MS) and Ames test results were used to study the Al2(SO4)3 and FeCl3 coagulation and sedimentation effluents in a pilot plant. Based upon the molecular structure of fulvic acid and the mechanism of organics coagulation, the authors propose a mechanism for fulvic acid adsorbing mutagenic organics in water. When the coagulant is fed into water, the metal ions will combine with fulvic acid to form complexes, this releases the organics and mutagen which are adsorbed and complexed by fulvic acid and results in an increase of mutagenic activity in the effluent. In addition, according to the principle of fulvic acid to generate free radicals and the chemistry of Fe3+, the authors discuss the impact of two coagulants on the generation of mutagenic activity. It is indicated that Fe3+ catalysing the reaction for fulvic acid to produce free radicals is the reason that the mutagenic activity in FeCl3 coagulation and sedimentation effluent is higher than in Al2(SO4)3 effluent.