Factors affecting UV/H2O2 inactivation of Bacillus atrophaeus spores in drinking water

• The inactivation is obtained under the synergy of UV light and H2O2.
• H2O2 played dual roles in the reactions, while a 0.5 mM dose performed best.
• The best inactivation effect can be achieved at pH 5.
• High irradiance and low initial cell density both favored reaction.
• The inhibited effect of anions followed the order: SO42− < NO3− < CO32−.

This study aims at estimating the performance of the Bacillus atrophaeus spores inactivation by the UV treatment with addition of H2O2. The effect of factors affecting the inactivation was investigated, including initial H2O2 dose, UV irradiance, initial cell density, initial solution pH and various inorganic anions. Under the experimental conditions, the B. atrophaeus spores inactivation followed both the modified Hom Model and the Chick’s Model. The results revealed that the H2O2 played dual roles in the reactions, while the optimum reduction of 5.88 lg was received at 0.5 mM H2O2 for 10 min. The inactivation effect was affected by the UV irradiance, while better inactivation effect was achieved at higher irradiance. An increase in the initial cell density slowed down the inactivation process. A slight acid condition at pH 5 was considered as the optimal pH value. The inactivation effect within 10 min followed the order of pH 5 > pH 7 > pH 9 > pH 3 > pH 11. The effects of three added inorganic anions were investigated and compared, including sulfate (SO42−), nitrate (NO3−) and carbonate (CO32−). The sequence of inactivation effect within 10 min followed the order of control group > SO42− > NO3− > CO32−.

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