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

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 5.88lg was received at 0.5mM H2O2 for 10min. 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 10min 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 (SO4(2)(-)), nitrate (NO3(-)) and carbonate (CO3(2)(-)). The sequence of inactivation effect within 10min followed the order of control group>SO4(2)(-)>NO3(-)>CO3(2)(-).