| This article had studied the the feasibility of ozone off-gas recycling to aeration tank,which has great value for industrial and practical application.This research investigated the impact of ozone to activated sludge by applying 14.68 mg/L,30.72 mg/L and 43.84 mg/L of O3 for sludge ozonation,respectively,while pure oxygen aeration was used as a parallel experiment.It includes the impact of ozone to the microbes and the process target of aeration tank,the impact of the supernate to the origin process was also studied.The results showed that no obvious changes were observed in pure oxygen aeration.However,the ozonation could cause disinfection and cell lysis,the effect were more obvious with higher ozone concentration;Sludge nitrification ability and biodegradation ability barely changed at 14.68 mg/L and 30.72 mg/L of O3 level,so,the aeration tank could keep normal operation.Meanwhile,the supernate after ozonation had no great inhibition to the origin process.While sludge nitrification ability and biodegradation ability deteriorated by 43.84 mg/L O3 and the recycling process cannot be carried out.Therefore,when the ozone concentration is 14.68-30.72mg/L,the off-gas could be recycled to aeration tank with adjusting reflow ratio,which could eliminate the respiration inhibition of supemate and reduce the hard COD. |
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