What is it about?
This work aimed at selecting materials capable of favouring biofouling build-up in order to develop plain coupons as alternative to expensive commercial biofouling mesh coupons. Plain coupons of copper, stainless steel (SS), polyvinyl chloride (PVC) and high density polyethylene (HDPE) were dipped and tested in a cooling water from a food industry. PVC and HDPE coupons showed promising responses and appear to be preferable since they are corrosion-free. Moreover, an experimental vibration sensor monitored biofilm adhesion on SS and PVC tubular coupons (simulating the respective sensor tubes), inside which flowed the water aforementioned. The stainless steel sensor tube and tubular coupons displayed the most satisfactory results, i.e., the highest vibration amplitude and the highest adhered biofilm mass, respectively. Biofilm adhesion onto the materials tested depended on their surface shear stress, effective roughness and hydrophobicity, as determined by scanning electron microscopy and goniometry.
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Why is it important?
• Materials which favour biofouling build-up were selected. • HDPE and PVC plain coupons showed promising results. • Biofilm adhesion monitored by a vibration sensor and quantified by tubular coupons. • Stainless steel tubular coupons & sensor tube showed the most effective responses. • Biofilm adhesion depends on shear stress, effective roughness and hydrophobicity.
Perspectives
The goals of selecting materials that favour biofilm formation and growth on tubular and plain coupons, as well as the assessment of a vibration sensor for the early detection of biofouling, were fulfilled. For such a purpose, an assay of biofilm adhesion on vibration sensor tubes, tubular coupons of SS and PVC, and plain coupons of copper, SS, HDPE and PVC was carried out. The vibration sensor tubes of SS were more effective than the ones of PVC for the detection of biofilm adhesion/removal. For the tubular coupons of the same materials and diameters of the vibration sensor tubes, the same conclusion was drawn, i.e., SS coupons yielded a higher mass of biofilm adhered. The preferential adhesion of biofilm on SS should be due to the higher surface shear stress (higher relative roughness) on this material in comparison to PVC. Concerning the plain coupons developed for easy detection of biofilm growth, stainless steel yielded the highest mass of biofilm adhered, but it is not recommendable for biofouling detection because it is prone to corrosion. The polymeric coupons of HDPE and PVC presented moderate masses of biofilm adhered, thus they may be used for biofilm detection, and they are corrosion-free. The effective roughness and hydrophobicity are surely relevant factors in the selection of plain materials for biofouling detection.
Diná Afonso
Instituto Superior Técnico
Read the Original
This page is a summary of: Selection of materials for biofouling detection in cooling water systems, Water Science & Technology Water Supply, September 2017, IWA Publishing,
DOI: 10.2166/ws.2017.191.
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