Evaluation of Static Mixers at Bench- and Pilot-scale for Enhanced Ozone Dissolution and Inactivation of Bacillus Subtilis in Water Treatment

摘要

The static mixer offers one alternative method for improving the efficiency of thedissolution of ozone gas and for optimizing the use of ozone in the disinfection process. Theoverall goals of this project are to quantify the potential benefits of ozone application utilizingstatic mixers through comprehensive bench-, pilot- and full-scale studies, under a wide variety ofoperating conditions and source waters. Bacillus subtilis was used as a surrogate forCryptosporidium for evaluating the effectiveness of the disinfection process. Preliminary resultsindicate that an integrated ozone disinfection process consisting of a static mixer, gas-liquidseparator and a plug flow contactor can achieve microbial inactivation that is comparable to anidealized well-mixed batch reactor. Pilot studies conducted in Gwinnett County, Georgiashowed that 5 Log inactivation of Bacillus subtilis was possible with low ozone doses whilekeeping bromate formation below the MCL of 10 μg/L.