Resumo (PT):
Abstract (EN):
Many industrial processes are susceptible to biofouling. The thickness and structure of such biofilms are
key factors in the design of effective cleaning strategies. A novel method based on fluid dynamic gauging
has been developed for measuring the thickness and the shear stress needed for removal of the biofilms
formed on cylindrical surfaces. The device operates with the test cylinder immersed in liquid: liquid is
withdrawn or ejected from a nozzle located near the biofilm surface. There is no net change of liquid
volume, making it ideal for sterile and aseptic operation and for studies using valuable liquids. Biofilm
removal may also be tested by using appropriate hydrodynamic conditions.
Calibration tests using ejection and suction flows in the laminar regime (Reynolds number around
100) indicated a measurement accuracy of ±19 m and showed good agreement with computational
fluid dynamics simulations. The device was commissioned in tests on Pseudomonas fluorescens biofilms
formed on high density polyethylene (HDPE) and stainless steel (SS) cylinders of diameter 25 mm under
conditions of mild shear stress (around 2 Pa in these tests). The biofilm thickness was not uniform to
the eye and measurements made over the surface of the test cylinders confirmed this: layer thicknesses
ranged from effectively 0–300 m. The biofilms formed on HDPE were thicker than those formed on SS.
Idioma:
Inglês
Tipo (Avaliação Docente):
Científica
Nº de páginas:
13