Water bacterial biofilms

Nelson, Y.M. et al., Lead distribution in a simulated aquatic environment Effects of bacterial biofilms and iron oxide, Water Res., 29, 1934, 1995. 

The discussion relating to the metabolism of bacteria in biofilms is of necessity short. Nevertheless it does draw attention to the complexity of bacterial biofilm formation and development, commonly encountered in heat exchangers associated with aqueous industrial systems such as cooling water. It is on account of these... 

Nichols [1994] concludes that in medically important biofilms, the glycocalyx (exopolysaccaride) material in bacterial biofilms up to 100 fjm thick, is not a significant barrier to the diffusion of antibacterial agents. Nicholls makes some tentative calculations on the time for penetration for different biofilm thicknesses. The assessment is based on a molecule with a difflisivity of 6.8 x 10" cm/s presumably through water. It would appear also that no account has been taken of... 

In this chapter we also address the core-sheU structure of metal fluorides for the case of FeF2, where the FeF2 is the core and carbon is the shell. According to Fedorov et al. (10), water will react very slowly with fluorides, yielding HF. The carbon shell is important because it will prevent this dissolution. Finally the use of metal fluorides to produce sterile abiotic surfaces and block bacterial biofilm formation is discussed. 

A unique type of corrosion referred to as copper by-product release, cuprosolvency, or blue water occurs in potable water systems constructed of copper tubing, and has been reported worldwide [92-95]. The problem is most often attributed to EPS induced metal concentration cells. The condition is characterized by the release of copper as fine particles in plumbing systems distributing soft water in the neutral or neutral-alkaline pH range. Water may contain between 5 to 300 ppm copper (as Cu +) as finely suspended precipitates. A bacterial biofilm and associated acidic EPS bind copper ions at the metal surface and alter the porosity of the oxide film [96]. Geesey and coworkers [97] characterized binding of an acidic polysaccharide to thin copper films and su ested a cupric ion interaction with carboxyl groups on EPS. These interactions promoted ionization of metallic... 

S. Maxwell, C. Devine, F. Rooney, I. Spark. Monitoring and control of bacterial biofilms in oilfield water handling systems. Paper No. 04752, Corrosion 2004, NACE International, Houston, TX, 2004. 

Figure 23.2.6. GCW process diagram. Effective hydrocarbon stripping in the water column is observed in these systems using a vacuum extraction. A circulation cell is created by directional flow of water in the vertical direction creating a capture zone extending several meters from the well. In addition a bioreactor (high surface area bacterial biofilm) can be used in the system to degrade low volatile contaminants [Adapted from Bemhartt et al., U.S. Patent 5,910,245, 1999]...

Bacterial bio films. Bacterial biofilms are complex, 3-D communities found nearly everywhere in nature and are also associated with many human diseases. Detailed metabolic information is critical to understand and exploit beneficial biofilms as well as combat anti biotic-resistant, disease-associated forms. Biofilm imaging, transport and metabolite measurement methods and their correlation for live, non-invasive monitoring of biofilm processes were correlatively applied. NMR methods provide macroscopic structure, metabolic pathway and rate data, spatially resolved metabolite concentrations and water diffusion profiles within the biofilm. In particular, current depth-resolved spectroscopy methods are appUed to detect metabolites in 140-190 nl volumes within biofilms. The entire 3-D biofilm structure was imaged using MRI. This was then correlated to a fluorescent CLSM image. 

Figure 4 Bacterial biofilm inside a water storage tank.

Maxwell S, Devine C, Rooney E, Spark I (2004) Monitoring and Control of Bacterial Biofilms in Oilfield Water Handhng Systems, Paper No. 04752, CORROSION 2004, NCAE International... 

Stein AA (1993) MIC treatment and prevention. In A practical manual on microbiologi-cally-influenced corrosion Kobrin G (ed) NACE Houston Texas USA Lee J (1998) Bacterial biofilms less likely on electropolished steel Agricultural Res p. 10 Percival SL, Knapp JS, Wales DS, Edyvean RGJ (2000) Metal and iuorgauic ion accumulation in biofihns exposed to flowing and stagnant water. Brit Corrosion J 36(2) 105-110 Sreekumari KR, Nandakumar K, Kikuchi Y (2004) Effect of metal microstructure on bacterial attachment A contributing factor for preferential mic attack of welds. Paper No. 04597. CORROSION 2004, NACE International... 

Nature of biofilm. A biofilm is said to consist of microbial cells (algal, fungal, or bacterial) and the extracellular biopolymer they produce. Generally, it is bacterial biofilms that are of most concern in industrial water systems, since they are generally responsible for the fouling of heat-transfer equipment. This is due in part to the minimal nutrients that many species require in order to grow. 

Williamson, K. and McCarty, P.L., Verification studies of the biofilm model for bacterial substrate utilization, J. Water Poll. Control Fed., 48, 281-296,1976. 

Heterotrophic bacterial processes dominate transformations in the sewer. There are similarities with the corresponding processes in biological treatment plants. It is, however, from the very beginning, important to emphasize that transformations of wastewater under sewer conditions and in activated sludge or biofilm systems proceed differently. The processes in sewers, treatment plants and receiving waters must be dealt with as an entity however, they must also be considered with their own specific characteristics. 

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