变喉部长径比文丘里式水力空化杀灭原水中病原微生物的试验研究

Experimental Study of Killing Pathogenic Microorganisms in Raw Water by Venturi Hydrodynamic Cavitation with Varying Throat Length-radius Ratio

基于浙江工业大学水力学实验室自主研发的变喉部长径比L/R文丘里(Venturi)式水力空化装置,考虑了4种喉部长径比L/R=10、30、60、100,4种原水占比(初始浓度)V_0/V=25%、50%、75%、100%,以菌落总数和大肠杆菌作为病原微生物指示菌,试验研究了喉部长径比、喉部流速、水力空化作用时间、原水初始浓度、空化数等因子对水力空化杀灭原水中病原微生物的影响。试验结果表明:空泡溃灭时产生的微射流、冲击波会使原水中病原微生物的细胞发生空蚀破坏,水流空化数越低,对大肠杆菌、菌落总数的杀灭率越高;流速较低或原水初始浓度较高时,其杀灭率随喉部长径比的增加逐渐增大;流速较高或原水初始浓度较低时,其杀灭率几乎与喉部长径比无关;增大喉部流速或延长水力空化作用时间,可进一步提高对病原微生物的杀灭效果。水力空化是一种无需添加消毒剂、无消毒副产物的新型生活饮用水消毒技术。

Based on the self-developed Venturi hydrodynamic cavitation device with varying throat length-radius ratio L/R of the Hydraulics Laboratory,Zhejiang University of Technology,4 throat length-radius ratios L/R=10,30,60 and 100,and 4 raw water percentages or initial concentrations V 0/V=25%,50%,75%and 100%were considered,escherichia coli and total colony count selected for indicator bacteria,effects of throat length-radius ratio,throat velocity,hydrodynamic cavitation time,raw water percentage and cavitation number on killing pathogenic microorganism in raw water by hydrodynamic cavitation were experimentally studied.The experimental results showed that cavitation damage of cells in pathogenic microorganism occurred due to microjet and shock wave due to cavitation bubble collapse.The lower the flow cavitation number,the higher the killing rate of escherichia coli and total colony count.When flow velocity was lower or raw water percentage was higher,the killing rate gradually increased with increase in throat length-radius ratio;when flow velocity was higher or raw water percentage was lower,the killing rate was almost independent to throat length-radius ratio.Killing effect of pathogenic microorganism can be further enhanced by the increase in throat velocity or prolonging cavitation time.Hydrodynamic cavitation is a novel disinfection technique of life and drinking water without disinfection by products(DBPs)and no need to add disinfectant.