方孔多孔板水力空化杀灭大肠杆菌的实验研究

Experimental study on disinfection of Escherichia coli by hydrodynamic cavitation behind square multi-orifice plates

传统的饮用水消毒技术是在原水中投加氯,但近年发现,氯在消毒的同时与水中有机化合物反应生成消毒副产物DBPs,其中最为常见的DBPs为三卤甲烷THMs、卤乙酸HAAs等,这些副产品具有"三致"(致癌、致畸、致突变)作用,严重威胁着人们的身体健康。为探索新的饮用水消毒方式,本文利用多孔板型水力空化反应装置,以大肠杆菌为原水病原微生物指示菌种,处理含有大肠杆菌的水样,使用平板菌落计数法求得不同时刻水样中大肠杆菌浓度。通过对不同孔口流速、不同几何参数多孔板、不同初始浓度菌液进行空化试验,提出了空化数、孔口流速、初始浓度、处理时间、孔口数量、孔口大小、孔口排列方式与大肠杆菌杀灭率的关系。试验结果表明,提高孔口流速、选取最佳初始浓度、延长处理时间、增多孔口数量和减小孔口大小可以提高大肠杆菌的杀灭率,水力空化对大肠杆菌具有显著的杀灭效果,可以作为新的消毒技术进一步研究。

Chlorination of raw water is a traditional technology for drinking water disinfection. However, recent studies have shown that chlorination generates byproducts DBPs as a result of chlorine reacting with organic compounds in water. The most common DBPs are THMs, HAAs and other harmful compounds, and all of them are carcinogenic, teratogenic and mutagenic, severely threatening human health. To explore new technologies of water disinfection, this paper describes an experimental study on disinfection of Escherichia coli, an indicator culture of pathogenic microorganisms, by using plates of square-shape multi-orifices as reactors of hydrodynamic cavitation. An agar plate colony-counting method was used for determination of the concentration of Escherichia coli in water samples taken from the flows behind the orifice plates, in the conditions of different orifice velocities, different orifice geometric parameters, and different initial concentrations of Escherichia coli. Our analysis focused on variations in the killing rate of Escherichia coli with several factors： cavitation number, orifice velocity, initial concentration, number and size of orifices on the plate, and arrangement of the orifices. The results show that killing rate can be increased by enhancing velocity, choosing appropriate initial concentration, improving treatment time, or increasing the number or decreasing the size of orifices. Hydrodynamic cavitation produces significant killing effect on Escherichia coli and it can serve as a new disinfection technology for further study.