Effect of pre-chlorination on intracellular organic matter( IOM) release and residual aluminum in Microcystis aeruginosa coagulation by aluminum

Pre-chlorination contributes to the inactivation of Microcystis aeruginosa and the release of intracellular organic matter( IOM),and the doses of chlorine show significant effects on these processes.As compared to the control system( 0 mg·L-1Cl 2),chlorine at low doses of 1 ~2 mg·L-1enhances the IOM release by 26% ~ 31% and UV 254 increase by 46% ~ 49%,mainly due to the elevated levels of IOM with moderate molar weight( MW) and high aromaticity.At high doses of chlorine( 3 ~ 4 mg·L-1),the levels of IOM with high MW increase whereas those with moderate MW decrease,and these effects lower UV 254,the aromaticity,and the IOM concentrations accordingly.The dissolved IOM with high MW and high aromaticity may be preferentially removed by Al coagulation.The released proteins during chlorination may form soluble Al-protein complexes to increase the levels of residual Al,which decreases at elevated Al doses.