TY - JOUR
T1 - Assessment of the efficacy of intermittent ozone disinfection
AU - Ahn, Chang Hoon
AU - Rittmann, Bruce
N1 - Funding Information:
This investigation was supported by the National Institute of Health through a Small Business Administration grant to Compact Membrane System (CMS), Inc. We would like to thank Kenneth Lan for the MBODS operation as an internship student. We also acknowledge the assistance of Professor Paul Westerhoff at Arizona State University for BDOC analysis and Mr. Daniel Avery of CMS for set-up of the MBODS.
PY - 2009/11
Y1 - 2009/11
N2 - An example of intermittent disinfection occurs in dentalunit water systems (DUWS), which are disinfected only for a specified time per each day. The efficacy of intermittent ozonation was evaluated using a laboratory-scale, membrane- based ozone disinfection system (MBODS), which delivers bubbleless dissolved ozone to the DUWS. A new tool - the weighted Ct value, or Cw, - was applied to interpret heterotrophic plate counts (HPC) data. To achieve the American Dental Association's (ADA's) criterion (<200 CFU{pipe}mL), the required ozone dosage was Cw > 0.07 mg-O3{pipe}L. However, even the highest ozone dosage (Cw > 0.130 mg{pipe}L) allowed biofilm HPC to persist at over 104 CFU{pipe}cm2. Although a higher Cw killed planktonic and biofilm bacteria more thoroughly, it also generated more biodegradable dissolved organic carbon (BDOC). Thus, this research illustrates the inherent trade-off of intermittent ozonation: a higher Cw kills more bacteria during the ozonation period, but creates more BDOC that fosters biofilm regrowth when ozonation is off.
AB - An example of intermittent disinfection occurs in dentalunit water systems (DUWS), which are disinfected only for a specified time per each day. The efficacy of intermittent ozonation was evaluated using a laboratory-scale, membrane- based ozone disinfection system (MBODS), which delivers bubbleless dissolved ozone to the DUWS. A new tool - the weighted Ct value, or Cw, - was applied to interpret heterotrophic plate counts (HPC) data. To achieve the American Dental Association's (ADA's) criterion (<200 CFU{pipe}mL), the required ozone dosage was Cw > 0.07 mg-O3{pipe}L. However, even the highest ozone dosage (Cw > 0.130 mg{pipe}L) allowed biofilm HPC to persist at over 104 CFU{pipe}cm2. Although a higher Cw killed planktonic and biofilm bacteria more thoroughly, it also generated more biodegradable dissolved organic carbon (BDOC). Thus, this research illustrates the inherent trade-off of intermittent ozonation: a higher Cw kills more bacteria during the ozonation period, but creates more BDOC that fosters biofilm regrowth when ozonation is off.
KW - Biofilm
KW - Dental unit water systems
KW - Intermittent disinfection
KW - Ozone
KW - Regrowth
KW - Weighted Ct
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U2 - 10.1080/01919510903210439
DO - 10.1080/01919510903210439
M3 - Article
AN - SCOPUS:77649149201
SN - 0191-9512
VL - 31
SP - 436
EP - 444
JO - Ozone: Science and Engineering
JF - Ozone: Science and Engineering
IS - 6
ER -