Integrated Approach for Biofilm Characterisation and Biomass Activity Control

Лазарова, Валентина; Pierzo, V.; Fontvielle, D.; Manem, J.

doi:10.2166/wst.1994.0361

Cited by 51 publications

(28 citation statements)

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“…The percentage of matrix polysaccharides was higher for the biofilms formed under 0.12 and 0.17 Pa. It has been proposed (Lazarova et al, 1994;Liu and Tay, 2002;Tay et al, 2001) that high detachment forces can induce the biofilms to secrete more EPS. However, there was no relationship apparent between the percentage of matrix proteins and polysaccharides rw increased.…”

Section: Resultsmentioning

confidence: 84%

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: Resultsmentioning

confidence: 84%

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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“…The reactor was seeded in batch operation with activated sludge according to a speci®c start-up procedure [11]. Municipal wastewater after secondary treatment was used as reactor in¯uent in continuous operation.…”

Section: Pilot Scale Reactor Operationmentioning

confidence: 99%

“…The bio®lm was removed from the support medium after 7.5 minutes ultrasound treatment in 30 s cycles. The biomass TP was measured according to the method of Lowry [11]. Biomass DM was determined by the gravimetric method.…”

Section: Analytical Proceduresmentioning

confidence: 99%

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Influence of dissolved oxygen on the nitrification kinetics in a circulating bed biofilm reactor

Nogueira

Лазарова²,

Manem³

et al. 1998

Bioprocess Engineering

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The in¯uence of dissolved oxygen concentration on the nitri®cation kinetics was studied in the circulating bed reactor (CBR). The study was partly performed at laboratory scale with synthetic water, and partly at pilot scale with secondary ef¯uent as feed water. The nitri®-cation kinetics of the laboratory CBR as a function of the oxygen concentration can be described according to the half order and zero order rate equations of the diffusionreaction model applied to porous catalysts. When oxygen was the rate limiting substrate, the nitri®cation rate was close to a half order function of the oxygen concentration. The average oxygen diffusion coef®cient estimated by ®t-ting the diffusion-reaction model to the experimental results was around 66% of the respective value in water. The experimental results showed that either the ammonia or the oxygen concentration could be limiting for the nitri®cation kinetics. The latter occurred for an oxygen to ammonia concentration ratio below 1.5±2 gO 2 /gN-NH 4for both laboratory and pilot scale reactors. The volumetric oxygen mass transfer coef®cient (k L a) determined in the laboratory scale reactor was 0.017 s A1 for a super®cial air velocity of 0.02 m s A1 , and the one determined in the pilot scale reactor was 0.040 s A1 for a super®cial air velocity of 0.031 m s A1 . The k L a for the pilot scale reactor did not change signi®cantly after bio®lm development, compared to the value measured without bio®lm. List of symbols

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“…The decrease in the dehydr ogenase to protein ratio was clearest, ranging from 2.43×10 The protein to polysaccharide ratio, which characterizes biofi lm intensity (Lazarova et al 1994), ranged from 0.13×10 weight decreased. The changes in biofi lm properties with depth may be due to the accumulation of organic matter along with water fl ow in this system.…”

Section: The Standard Analysis Of Biofi Lm Parametersmentioning

confidence: 99%

The influence of hydraulic loading on biofilm properties in a subsurface wastewater infiltration system

Zhang¹,

Yang²

2016

Archives of Environmental Protection

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Keywords: subsurface wastewater infi ltration system, biofi lms, hydraulic loading, spatial distribution, biofi lm properties. Abstract:In this s tudy, a pilot-scale subsurface wastewater infi ltration system (SWIS) was deployed to study landscape water treatment. The goal of the study was to investiga te the effects of hydraulic loading on pollutant removal and the spatial distribution of biofi lm properties in SWIS. Results showed that the effi ciencies of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal degraded as hydraulic loading increased. Furthermore, quantities of the biofi lm properties parameter s increased with the hydraulic loading. Polysacch aride and protein levels ranged from 560 to 1110 μg/g fi ller and 60 to 190 μg/g fi ller, respectively, at a hydraulic loading of 0.2 m/d. At a hydraulic loading of 0.4 m/d, the quantities of polysaccharide and protein ranged from 1200 to 3300 μg/g fi ller and 80 to 290 μg/g fi ller, respectively. Biofi lm intensity and biofi lm activity per unit weight decreased with the increase in hydraulic loading.Unauthenticated Download Date | 5/13/18 7:01 AM

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Integrated Approach for Biofilm Characterisation and Biomass Activity Control

Cited by 51 publications

References 0 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

Influence of dissolved oxygen on the nitrification kinetics in a circulating bed biofilm reactor

The influence of hydraulic loading on biofilm properties in a subsurface wastewater infiltration system

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