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The effectiveness of ozone treatment for improving the biodegradability of recalcitrant pollutants has been proved by investigating the ozonation reaction of Methyl tert-Butyl Ether (MTBE) as a bioresistant gasoline oxygenate. Laboratory scale experiments have been carried out at room temperature by bubbling for 120 minutes ozonated air (3.4 ppm/min) into 3 liter of an alkaline (pH=11.5) aqueous solution (100 mg/L) of MTBE. The experimental results indicated that during the ozonation, complete MTBE degradation occurs in 100 minutes and after this time, ozone consumption goes on very slowly. At the end of the ozonation, after 100 minutes, the initial value of COD (256 mg O2/L) is 98 and corresponds to a relative removal of about 62%. As for MTBE solution biodegradability expressed as (BOD5) / (COD) ratio, during the first 90 minutes, its value regularly increases from lowest 0.01 up to a maximum of 0.68 that corresponds to an ozone consumption of 1.25 mg per each mg of COD initially present in the solution. The research showed that partial degradation of MTBE in the advanced oxidation processes results an increase in its biological degradation. But more oxidation results lower  (BOD5) / (COD) ratio. Also the research showed that for idealization of the chemical oxidation conditions of MTBE, it needs to decrease COD to 46-68% before the biological degradation. The experimental results for determining the rate of MTBE removal due to stripping showed that about 14% of MTBE strips out after an hour of sparging with oxygen gas. The fraction of MTBE oxidized and/or striped increases to about 28% (in pH=7) and 70% (in pH=11.5) with ozonation over the same time period.