Trihalomethane Formation Downstream of Spray Aerators Treating Disinfected Groundwater

Abstract

Total trihalomethane (TTHM) formation was evaluated in disinfected groundwater that had been treated using spray aeration. A bench-scale air-stripping test apparatus was operated using two alternative spray nozzle configurations: a bench-scale (BS) spray head and an off-the-shelf (OTS) spray nozzle. Finished chlorinated water samples were collected from two Florida groundwater supplies. The Babson Park water treatment plant (BPWTP) contained bromide at below detection levels of >0.025 mg/L; the Oviedo Mitchell-Hammock water treatment plant (OWTP) contained ~0.17 mg/L bromide. Chlorine residuals were maintained downstream of spray aeration treatment at 1.0 mg/L with no apparent loss from aeration. The BS spray nozzle resulted in TTHM removals of 45.2 ± 3.3% for the BPWTP and 37.7 ± 3.1% for the OWTP. The OTS spray nozzle removed 54.7 ± 3.9% and 48.1 ± 6.6% of TTHMs for BPWTP and OWTP, respectively. Lower percent removals in the OWTP were attributed to bromide and subsequent formation of brominated TTHMs in the supply.