Ozonation of a real red-meat-processing wastewater was conducted in a semi-batch reactor to explore the possibility of the water reuse. The experimental results revealed that ozone was very effective in disinfection of the red-meat-processing wastewater. After 8 min of ozonation with an applied ozone dose of 23.09 mg min(-1) liter(-1) of wastewater, 99% of aerobic bacteria, total coliforms and Escherichia coli were inactivated. Empirical models were developed to predict the microbial inactivation efficacy of ozone from the CT values for the real red-meat-processing wastewater. A correlation was also derived to estimate the CT values from the applied ozone dose and the ozone contact time. The results also revealed that under the ozonation condition for 99% inactivation of aerobic bacteria, total coliforms and E coli, the decrease in the chemical oxygen demand and the S-day biological oxygen demand of the wastewater were 10.7% and 23.6%, respectively. However, ozonation under this condition neither improved the light transmission nor reduced the total suspended solids (TSS) despite of the decolorization of the wastewater after ozonation. (c) 2005 Society of Chemical Industry.