A Comparison of the Role of Two Blue-green Algae in THM

The contribution of two blue-green algae species, Anabaena flos-aquae and Microcystis 16 aeruginosa, to the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) was 17 investigated. The experiments examined the formation potential of these disinfection by-products 18 (DBPs) from both algae cells and extracellular organic matter (EOM) during four algal growth 19 phases. Algal cells and EOM of Anabaena and Microcystis exhibited a high potential for DBP 20 formation. Yields of total THMs (TTHM) and total HAAs (THAA) were closely related to the 21 growth phase. Reactivity of EOM from Anabaena was slightly higher than corresponding cells, 22 while the opposite result was found for Microcystis. Specific DBP yields (yield/unit C) of 23 Anabaena were in the range of 2-11mol/mmol C for TTHM and 2-17mol/mmol C for THAA, 24 while those of Microcystis were slightly higher. With regard to the distributions of individual 25 THM and HAA compounds, differences were observed between the algae species and also 26 between cells and EOM. The presence of bromide shifted the dominant compounds from HAAs to 27 THMs.