scholarly journals Impacts of motile Escherichia coli on air-water surface tension

2020 ◽  
Vol 205 ◽  
pp. 08003 ◽  
Author(s):  
Yumeng Zhao ◽  
Boyoung Jeong ◽  
Dong-Hun Kang ◽  
Sheng Dai
Keyword(s):  
Escherichia Coli ◽  
Surface Tension ◽  
Water Surface ◽  
Diffusion Processes ◽  
Lower Surface ◽  
Flow In Porous Media ◽  
Maximum Bubble Pressure ◽  
E Coli ◽  
Bubble Pressure ◽  
Ring Method

Immiscible multiphase flow in porous media is largely affected by interfacial properties, manifested in contact angle and surface tension. The gas-liquid surface tension can be significantly altered by suspended particles at the interface. Particle-laden interfaces have unique properties, for example, a lower surface tension of interfaces laden with surfactants or nanoparticles. This study investigates the impacts of a motile bacterium Escherichia coli (E. coli, strain ATCC 9637) on the air-water surface tension. Methods of the maximum bubble pressure, the du Noüy ring, and the pendant droplet are used to measure the surface tension of the motile-bacteria-laden interfaces. Measured surface tension remains independent to the E. coli concentration when using the maximum bubble pressure method, decreases with increased E. coli concentration in the du Noüy ring method, and presents time-dependent changes by the pendant drop method. The analyses show that the discrepancies may come from the different convection-diffusion processes of E. coli in the flow among various testing methods.

scholarly journals Numerical investigation of the spatial distribution of Escherichia coli in river deltas for different values of river discharge, temperature and irradiation of the water surface

2020 ◽  
Vol 3 (1) ◽  
pp. 69-76
Author(s):  
Nicoletta Leonardi ◽  
Constantinos Matsoukis ◽  
Iacopo Carnacina
Keyword(s):  
Escherichia Coli ◽  
Spatial Distribution ◽  
River Discharge ◽  
Water Surface ◽  
Shelf Area ◽  
Quality Model ◽  
Fecal Matter ◽  
E Coli ◽  
River Deltas ◽  
Discharge Temperature

Abstract Escherichia coli and other enteric pathogens presence indicate that the water has been contaminated with fecal matter. River deltas are population hotspots which are becoming increasingly urbanized and where poor sanitation has been frequently identified as a pressing issue. In this study, we have investigated the spatial distribution of E. coli in river deltas under varying river discharge, temperature and irradiation at the water surface. A hydrodynamic and water quality model has been used to reproduce an idealized river delta configuration and to investigate the spatial distribution of E. coli across the delta floodplain and channels. The concentration of E. coli rapidly declines downstream, following a tripartite trend with different decline rates on the delta front, pro-delta and shelf area. The highest differences in the spatial distribution of E. coli bacteria occur for low-river discharge values. Temperature and irradiation both influence the concentration of E. coli and mostly influence downstream areas and smaller channels.

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