Microbial Biofouling: Unsolved Problems, Insufficient Approaches, and Possible Solutions

Flemming, Hans‐Curt

doi:10.1007/978-3-642-19940-0_5

Cited by 112 publications

(99 citation statements)

References 111 publications

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Section: Introductionmentioning

confidence: 99%

“…Since biofilms are complex biological structures adhered to a sur-face, these strategies often fail, as the removal of biomass is neglected. Hence, cleaning the biomass from the surfaces is fundamental for controlling biofilm development (Flemming, 2011).In the biofilm formation process, the hydrodynamic conditions define the transport of the cells, oxygen and nutrients from the bulk fluid to the microbial film (Bryers and Characklis, 1981; Simões et al, 2007b;Stoodley et al, 1999). In fact, the overall flow conditions affect the biofilm structure, as they influence the bulk liquid velocity and shear stress exerted on the surface (Cao and Alaerts, 1995;Peyton, 1996; Vieira and Melo, 1999).…”

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confidence: 99%

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The effect of shear stress on the formation and removal of Bacillus cereus biofilms

Lemos

Mergulhão

Melo

et al. 2015

Food and Bioproducts Processing

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A b s t r a c tThe influence of the shear stress (rw) under which biofilms were formed was assessed on their susceptibility to removal when exposed to chemical and mechanical stresses. A rotating cylinder reactor was used to form biofilms, allowing the simulation of rw conditions similar to those found in industrial settings, particularly in areas with low rw like elbows, corners, valves and dead zones. Bacillus cereus was used as a model bacterium for biofilm formation.Biofilms were formed on AISI316 stainless steel cylinders under different rw (estimated at 0.02, 0.12 and 0.17 Pa) for 7 days. Some phenotypic characteristics, including thickness, biomass production, cellular density and extracellular proteins and polysaccharides content were assessed. Biofilm density was found to increase significantly with rw while the thickness decreased. Also, biofilms formed at 0.02 Pa had lowest biomass content, cell density and extracellular polysaccharide content. Those characteristics were not statistically different for the biofilms formed under 0.12 and 0.17 Pa.Ex situ tests were performed by treating the biofilms with the biocide benzyldimethyldodecyl ammonium chloride (BDMDAC), followed by exposure to increasing rw conditions, up to 1.84 Pa (whereas the maximum rw used during growth was 0.17 Pa). The biofilms formed under low rw were more resistant to removal caused by the BDMDAC action alone. Those formed under higher rw were more resistant to the mechanical and the combined chemical and mechanical treatments. The amount of biofilm remaining on the cylinders, after both treatments was statistically similar for biofilms formed under 0.12 and 0.17Pa. The resistance of biofilms to removal by mechanical treatment (alone and combined with BDMDAC) was related to the amount of matrix polysaccharides.However, none of the methods investigated were able to remove all the biofilm from the cylinders. IntroductionThere is a lack of efficient strategies to clean stagnant zones in industrial plants (Brooks and Flint, 2008). Crevices, corners, dead zones, valves or areas where the mixing rate is low are almost inevitable. Stagnation promotes bacterial accumulation, ultimately leading to biofouling (Manuel et al., 2010). Biofouling is a damaging problem, affecting the energetic efficiency of industrial processes, causing corrosion of the surfaces, decreasing product quality and eventually promoting the spread of pathogens and resistant infectious diseases (Costerton et al., 1999;Ludensky, 2003;Srey et al., 2013). In industrial settings, surface disinfection is usually focused on the use of biocides, aiming to inactivate the microorganisms (Cloete et al., 1998;Faille et al., 2013). Since biofilms are complex biological structures adhered to a sur-face, these strategies often fail, as the removal of biomass is neglected. Hence, cleaning the biomass from the surfaces is fundamental for controlling biofilm development (Flemming, 2011).In the biofilm formation process, the hydrodynamic conditions define the transport of the cells, oxyg...

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

The effect of shear stress on the formation and removal of Bacillus cereus biofilms

Lemos

Mergulhão

Melo

et al. 2015

Food and Bioproducts Processing

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“…In addition, microbes can enter water utility distribution systems and biofilm formation may account for the persistence of microbes in the distribution systems [40]. The walls of the pipes in the distribution system provide ideal surfaces for microbial colonization [41].…”

Section: Discussionmentioning

confidence: 99%

Quality Assessment of Drinking Water in Tanta City, Egypt

Khalil¹,

Salem²,

Gheda³

et al. 2013

JESE-B

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Abstract:The physico-chemical and biological (algal and bacterial) quality of tap water in Tanta City were elucidated. Samples were collected during December 2011, covering all the water plants and the areal extension of the pipe line network in Tanta. Total dissolved solids content classifies water origin into surface water, shallow and deep groundwater. Fe, Mn and hardness in some samples of groundwater origin are obviously exceeding the WHO (World Health Organization) limit. Mostly, green algae are found (31 species), followed by diatoms (19 species), then blue-green algae (13 species). CCA (Canonical Corresponding Analysis) indicates that green algae are strongly correlated with pH, NH 4 , alkalinity, Mn and Si; diatoms with EC (electric conductivity), turbidity, Zn and Si and blue green algae with EC and alkalinity. 50% of samples of surface origin, 80% of samples of both deep and shallow groundwater origins crossed WHO and Egyptian guideline in their content of mean TCC (Total Coliform Count). CCA estimates strong correlations of TCC with temperature, NH 4 and PO 4 ; E. coli with EC; heterotrophic bacteria with turbidity and NO 3 ; Salmonella sp. with Si and SO 4 and Pseudomonas aeruginosa with Mn. Finally, the water plants treatment may be not effective and pipes serve as a reservoir for pathogenic microorganisms.

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“…For the purpose to destroy the structure of biofilm, polysaccharides lyases and proteases have been invented to cleave the structure of polysaccharides and proteins, respectively [12,93,94]. However, this method cannot provide a comprehensive control for biofouling, since the enzymes are designed specifically to target on polysaccharides and proteins [13,95]. In addition, the production of biochemical enzymes is a costly process, and degrading enzymes cannot be reuse after cleaning [12].…”

Section: Prevention Methodsmentioning

confidence: 99%

“…However, many studies have reported that biofouling cannot be removed effectively using the standard chemical cleaning method [8][9][10]. The application of chemical cleaning agents in large quantities has also caused significant operational costs and environmental issues for their disposal [11][12][13].…”

Section: List Of Tablesmentioning

confidence: 99%

Biofouling control of reverse osmosis membranes using free nitrous acid

Filloux¹,

Wang²,

Pidou³

et al.

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Reverse osmosis (RO) membranes have been widely applied in membrane filtration processes for water purification, since the high selective RO membranes are designed to reject all materials with particle diameter larger than 10 angstrom (Å) [1]. However, this optimal selectivity leads to fouling that can greatly affect the performance and productivity of RO membranes. Biofouling remains as one of the major operational problems in RO processes and is caused by unwanted deposit and growth of microorganisms on the membrane. Numerous biofouling control strategies have been developed to restore the performance of RO membranes, but none of them are able to prevent or remove biofouling completely. A novel cleaning technique using a weak and monobasic acid (pKa=3.34, 25℃) named free nitrous acid (FNA) in combined with hydrogen dioxide (H 2 O 2 ) was proposed.The effects of FNA with or without H 2 O 2 on biofouling of RO membranes were investigated in Chapter 4, five RO membranes with different degree of biofouling were cleaned using FNA has achieved higher biomass removal than NaOH for both heavily fouled (86-96% versus 41-83%) and moderately fouled (92-95% against 89-92%) membranes, respectively.In accordance to the biomass removal, 6-32% of viable cells remained on the moderately fouled RO membranes under the impact of FNA cleaning (pH 3), whereas 38-58% of viable cells stayed on the heavily fouled RO membranes. These results revealed that FNA cleaning is more effective for moderately fouled membranes, implying that early cleaning for biofouling is preferable. Although applying FNA alone, or combining it with H2O2 have shown better efficiency at biofouling removal than NaOH, the cleaning efficiency has not been significantly improved (<1% of enhancement) by adding H 2 O 2 to FNA cleaning solutions. The effects of FNA on scaling of RO membranes were also studied using the same cleaning protocol developed for biofouling control. The results showed that FNA solutions at pH 2.0 and 3.0 were as efficient as conventional cleaning acids (hydrochloric acid and citric acid). The scaling layers which contain 32.4±1.7 g/cm 2 of calcium were completely removed by all acidic cleaning solutions. Based on the results, FNA is shown to be a promising ii cleaning agent for RO membrane biofouling and scaling removal.Further investigation focused on the effectiveness of FNA for biofouling prevention in RO processes (Chapter 5). The results showed that weekly FNA cleanings were unable to prevent fouling in the RO filtration systems, as the hydraulic performances (permeability and salt rejection) of RO membranes have gradually declined over two to three weeks filtration period.Although FNA cleaning was able to restore the permeability of RO membranes for one to two days, continuing declined permeability implied that the fouling rate was greater than the inhibition rate of FNA. The results of prevention tests also showed that FNA was more efficient at biomass inactivation and removal. The biomass contents and viable cells of the fouli...

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Microbial Biofouling: Unsolved Problems, Insufficient Approaches, and Possible Solutions

Cited by 112 publications

References 111 publications

The effect of shear stress on the formation and removal of Bacillus cereus biofilms

The effect of shear stress on the formation and removal of Bacillus cereus biofilms

Quality Assessment of Drinking Water in Tanta City, Egypt

Biofouling control of reverse osmosis membranes using free nitrous acid

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