超声灭活水中贾第鞭毛虫影响因素及机理研究

Influencing Factors and Mechanism of Giardia Inactivation in Water by Ultrasonic Irradiation

采用超声（Ultrasonic,US）灭活水中贾第鞭毛虫,探讨了有机物、浊度及无机离子浓度对超声灭活的影响,并通过扫描电镜观察探究了超声灭活贾第鞭毛虫的机理.结果表明：超声灭活贾第鞭毛虫灭活率随腐殖酸浓度的增加而降低,当腐殖酸浓度为50.0 mg/L时灭活率降低至80.6％;在浊度0～20.0 NTU范围内,超声灭活贾第鞭毛虫的灭活率先升高后降低,当浊度为1.0 NTU时达到最佳灭活效果（98.6％）;Ca2＋,Zn2＋和SO2-对超声灭活贾第鞭毛虫的灭活率影响不明显,当Ca2＋浓度为1.0 mg/L时,贾第鞭毛虫灭活率为96.3％,表明低浓度Ca2＋对灭活略有促进作用;HCO3-浓度增加,贾第鞭毛虫灭活率下降,当HCO3-浓度为100 mg/L时灭活率下降至83.8％.扫描电镜形态学观察表明超声可以破坏贾第鞭毛虫细胞表面结构,可得出超声空化过程产生的机械剪切作用是超声灭活贾第鞭毛虫的主要原因.

Ultrasonic was adopted for inactivating Giardia in water. The effect of organic substance, turbidity and inorganic ions on ultrasonic inactivation was investigated. The mechanism of ultrasonic inactivation of Giardia was studied by scanning electron microscopy. Results indicated that the inactivation rate decreased with the increase of humie acid concentration, when the concentration of humic acid was 50.0 mg/L, the inactivation rate reduced to 80.6%. In the range of 0-20 NTU turbidity, the inactivation rate first increased and then decreased, when the tur- bidity was 1.0 NTU, the inactivation rate reached maximum （98.6%）. The effect of Ca2 ＋ , Zn2 ＋and SO24 content on the inactivation was little, and low concentration of Ca2＋ （1.0 mg/L） could increase the inactivation rate to 96.3%. The increase of HCO3- concentration could reduce the inactivation rate, when the concentration was 100 mg/L the inactivation rate was 83.8%. It was obvious that ultrasonic damaged the cell structure of Giardia by scanning electron microscopy morphological observation, which suggested that the mechanical destruction due to the cavitation was the major factor of inactivating Giardia by ultrasonic.