LAUSR

Abstract Ozonation is broadly used as a disinfection technique for inactivation of pathogens in drinking water or reclaimed water. The conventional Chick-Watson model (C-W model) considering ozone exposure is sub-optimal in predicting the inactivation performance by ozonation in reclaimed water. In this study, the Escherichia coli (E. coli) and the Bacillus subtilis (B. subtilis) spore were used as test microorganisms and ozonation experiments were carried out upon different systems. The relationship between experimental inactivation and TOD was found to follow an S-shape curve. A novel and practical empirical model (L-I model) was set up to simulate the inactivation performance in reclaimed waters, regarding the transferred ozone dose (TOD), the instantaneous ozone demand (IOD) and the microbial resistance to ozone as the main parameters. According to the data fitting results, the parameters for E. coli and B. subtilis spores were determined. With TOD in 0–20 mg L−1 and IOD in 2–5 mg L−1, the calculated inactivation rates of the two test microorganisms could successfully match the experimental data derived from the batch ozonation test and the semi-continuous ozonation test for reclaimed water disinfection. The squared correlation coefficients (R2) for different tests range from 0.86 to 0.96 and the average relative errors (δ) are 0.08–0.59. This result verified that the L-I model is a practical way to simulate performances of ozonation systems for reclaimed water disinfection. Based on the model, the effects of water quality (IOD) and microbial resistance on disinfection performance were also analyzed.