Variation in assimilable organic carbon formation during chlorination of Microcystis aeruginosa extracellular organic matter solutions

This study investigated the chlorination of Microcystis aeruginosa extracellular organic matter (EOM) solutions under different conditions, to determine how the metabolites produced by these organisms affect water safety and the formation of assimilable organic carbon (AOC). The effects of chlorine dosages, coagulant dosage, reaction time and temperature on the formation of AOC were investigated during the disinfection of M.aeruginosa metabolite solutions. The concentration of AOC followed a decreasing and then increasing pattern with increasing temperature and reaction time. The concentration of AOC decreased and then increased with increasing chlorination dosage, followed by a slight decrease at the highest level of chlorination. However, the concentration of AOC decreased continuously with increasing coagulant dosage. The formation of AOC can be suppressed under appropriate conditions. In this study, chlorination at 4 mg/L, combined with a coagulant dose of 40 mg/L at 20°C over a reaction time of 12 hr, produced the minimum AOC.

a. Time-dependent formation of AOC following chlorination of different concentrations of Microcystis aeruginosa solutions at pH 7.0, chlorine dosage 20 mg-Cl2/L and a temperature of 20 ± 1°C. b. Levels of AOC following chlorination of different concentrations of M.aeruginosa solutions with different concentrations of chlorine at pH 7.0, with a reaction time of 48 hr and a temperature of 20 ± 1°C. c. Concentration of AOC as a function of coagulant dosage after 6 hr chlorination, for different concentrations of M.aeruginosa solutions at pH 7.0, chlorine dosage: 4 mg Cl2/L. d. The concentration of AOC as a function of temperature after 6 hr chlorination for different concentrations of M.aeruginosa solutions at pH 7.0, chlorine dosage: 4 mg-Cl2/L.Figure optionsDownload as PowerPoint slide