An overview on the reactors to study drinking water biofilms

Gomes, Inês B.; Simões, Manuel; Simões, Lúcia C.

doi:10.1016/j.watres.2014.05.039

Cited by 97 publications

(59 citation statements)

References 120 publications

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“…The low shear stresses simulated with this reactor are often found in elbows, valves, dead zones, corners and in sudden pipe expansions (Jensen and Friis, 2005;Lelièvre et al, 2002). Also, typical shear stress values found in drinking water distribution systems are in the range of those used in this study (Gomes et al, 2014).…”

Section: Introductionmentioning

confidence: 68%

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: 68%

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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“…Several problems associated with the management of these systems must be traced and addressed to improve the quality of the served water and of the supply, thus, to improve the efficiency of DWDS management. Biofilm is, from a microbiological perspective, one of the main sources of problems reported on DWDSs [11].…”

Section: Publicationsmentioning

confidence: 99%

“…Current approaches to study biofilm development in DWDSs The location of the coupons resembles better a real pipe situation and facilitates the sampling process. Generally, the removal of coupons does not change the flow conditions [11]. • Flow cell system.…”

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confidence: 99%

“…The coupons are removable and are inserted in the inner wall allowing for biofilm sampling over time. However, this system may present different configurations [11].…”

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confidence: 99%

“…Screws with slides are mounted on the front side and placed in these holes ( Figure 3.4). They are aligned parallel to the water flow and can be removed independently [11].…”

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Assessing biofilm development in drinking water distribution systems by Machine Learning methods

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Biofilm Formation in Water Supply Pipes

Xiao¹,

Waheed²

2019

Encyclopedia of Water

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Biofilm formation in water supply pipes is ubiquitous despite the practice of keeping a certain level of disinfectant residual. Biofilms in water supply pipes play a dominant role in shaping the microbial community and governing the microbial quality of tap water. However, this role has long been overlooked largely due to the unavailability of in situ biofilm monitoring tools and complexity of biofilm ecology. Recent development in molecular biology techniques has opened up a new window for biofilm studies, and thus sparked a new boom in research on biofilms in water supply pipes. This article introduces the new knowledge of occurrence and significance of biofilms in water supply pipes, their impacts on water quality and relationships with pipe corrosion. Then the factors affecting biofilm formation and methods to control it are elaborated. Furthermore, new insights into the microbial ecology of biofilms are presented, which include the dominant microorganisms and their potential roles in biofilms, the diversity and richness of the microbial communities, etc. At the end, future perspectives of research on biofilms in water supply pipes are discussed.

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An overview on the reactors to study drinking water biofilms

Cited by 97 publications

References 120 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

Assessing biofilm development in drinking water distribution systems by Machine Learning methods

Biofilm Formation in Water Supply Pipes

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