Relatively high trihalomethane (THM) and haloacetic acid (HAA) concentrations were formed from chlorination of six coagulated
treated waters during the first couple of hours, where 35-45% of the 5 day TTHM formation and
42-53% of the 5 day HAA5 formation were formed at 4 hours. For a given treated water the
chlorine demand was not a good indicator of short- and long-term TTHM and DXAA
formations, though the 5-day yields were consistently higher than the 1-day yields, where as the
TXAAs formed per mg of chlorine consumed was the same for short- and long-term periods.
Waters that were enhanced coagulated to a total organic carbon (TOC) value less than 4 mg/L and TSUVA value of 2
L/mg-m and chlorinated for CT values less than 850 mg-min/L within 4 hours at a Cl2:TOC dose
of 1.5 mg/mg, 20ºC, pH 8.0 and a Br-:TOC ratio less than 21 µg/mg, formed TTHM and HAA5
formations less than the MCLs. Includes 10 references, tables, figures.