Reduction of microbial biofilm formation using hydrophobic nano-silica coating on cooling tower fill material

Abstract

A cooling tower is a heat removal device, which extracts waste heat to the atmosphere through the cooling of a water stream to a lower temperature. Cooling towers are frequently associated with biofilm problems and Legionnaires disease outbreaks. Where biofilms can cause clogging and corrosion, reduction of biofilms is important for operational reasons and public health. Therefore, effective anti-biofilm strategies are needed in practice. The aim of the present study was to reduce biofilm formation using a nano-hydrophobic coating on cooling tower fill materials -polypropylene cooling tower fill material was coated with nano-silica. The effectiveness of the hydrophobic coating was investigated for a 6-month test period in a model cooling tower system, by monthly counting of the surface-associated bacteria using an epifluorescence microscope. A significant reduction (up to 4 log) in surface-associated bacteria was observed on coated test samples in comparison to uncoated control coupons. This study is the first report regarding the use of nano-silica coatings on cooling tower fills. The coating can be easily fabricated and the range of possible applications can be expanded to include a variety of conditions.

Effect of zinc oxide film morphologies on the formation of Shewanella putrefaciens biofilm

“…It was reported that L. monocytogenes adhered greater to hydrophilic surfaces than to hydrophobic ones under the same growth condition (20 C for 24 h)-93.8% and 81.3% biofilms were formed on hydrophilic surfaces (stainless steel and glass, respectively), with just 6.2% on hydrophobic surface (polystyrene). 34 T€ uretgen 35 reported that hydrophobic nanosilica coating could substantially reduce (up to four magnitude) biofilm formation on fill material in a cooling tower after examining coupons that were exposed to the bacteria. Schaer et al 36 found that hydrophobic coatings can inhibit biofilms formation-covering surfaces with hydrophobic coatings could significantly reduce bacterial attachment and adhesion.…”

Critical analysis of methods to determine growth, control and analysis of biofilms for potential non-submerged antibiofilm surfaces and coatings

“…Contact active surfaces utilized a range of approaches including plasma [ [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] , [66] , [67] , [68] , [69] , [70] , [71] , [72] ], amino-acids, polypeptides, enzymes [ [73] , [74] , [75] , [76] , [77] , [78] , [79] , [80] , [81] , [82] , [83] , [84] ], hormones [ 85 ], neurotransmitters [ 86 ] and polymers or copolymers [ [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] , [66] , [67] ]. Antiadhesive approaches included nanospikes [ 87 ], electrochemical etching [ 88 ], patterning [ 89 ], hydrophobic modifications [ [90] , [91] , [92] , [93] ], and included polymers [ [94] , [95] , [96] ], metals [ 97 ] and coatings using novel approaches such as candle soot [ 98 ].…”

Shelf-life, bioburden, water and oxygen permeability studies of laser welded SEBS/PP blended polymer

“…However, studies have shown that hydrophobic surfaces are capable of discouraging microbe attachment through the optimal balance of hydrophobicity and other physicochemical surface properties 28 , 86 , 87 . The lower bioburden on SEBS/PP can also be attributed to the interactions such as electrostatic forces acting in conjunction with low surface energy and surface smoothness to deter the attachment of microbes of the SEBS/PP surface 88 , 89 . As medical devices such as blood bags has the potential to be contaminated by microorganisms via high touch surfaces potentially leading to infections, it is crucial that the potential of blood bags to carry microbial loads be reduced 90 .…”