Biofilm monitoring

It is now widely recognized that sessile microorganisms cause the most damage in industrial water systems, and the development of biocides is directed towards biofilm. In order to measure the effectiveness of a biofilm control program, it is essential to accurately monitor the development of biofilms in a system and record their response to control measures. 

Mollusk type Min. Spawning Temp., °C Adult shell length, cm Life span, years Planktonic period, days Settlement seasons Larval size, pm 

As for the field monitoring of biofilms, there is a need for a rapid method of quantification of biofilm presence in the system (more reproducible than ATP measurements). Plate counts and other traditional methods that are still used to measure microbiological activity in industrial systems are slow, labor intensive, and often not representative of sessile growth. 

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The use and inspection of mesh screen coupons or washers placed in simple biofilm monitors can also help in biofilm control evaluation. Essentially, if an inspection gives some assurance that the cooling system is clean, it most probably is clean ... 

Figure 2 A continuous flow biofilm monitoring system.

Ludensky, M. L., 1998. An automated system for biofilm monitoring. J. of Industrial Microbiology and Biotechnology 20(2), 109-115. 

Sabater S, Guasch H, Ricart M, Romani AM, Vidal G, Kliinder C, Schmitt-Jansen M (2007) Monitoring the effect of chemicals on biological communities. The biofilm as an interface. Anal Bioanal Chem 387 1425... 

A simplification of the polarization resistance technique is the linear polarization technique in which it is assumed that the relationship between E and i is linear in a narrow range around E . Usually only two points ( , 0 are measured and B is assumed to have a constant value of about 20 mV. This approach is used in field tests and forms the basis of commercial corrosion rate monitors. Rp can also be determined as the dc limit of the electrochemical impedance. Mansfeld et al. used the linear polarization technique to determine Rp for mild steel sensors embedded in concrete exposed to a sewer environment for about 9 months. One sensor was periodically flushed with sewage in an attempt to remove the sulfuric acid produced by sulfur-oxidizing bacteria within a biofilm another sensor was used as a control. A data logging system collected Rp at 10-min intervals simultaneously for the two corrosion sensors and two pH electrodes placed at the concrete surface. Figure 2 shows the cumulative corrosion loss (Z INT) obtained by integration of the MRp time curves as ... 

H. A. Videla, P. S. Guiamet, O. R. Pardini, E. Echarte, D. Trujillo, and M. M. S. Freitas. Monitoring biofilms and MIC (microbially induced corrosion) in an oilfield water injection system. In Proceedings Volume. Annu NACE Corrosion Conf (Corrosion 91) (Cincinnati, OH, 3/11-3/15), 1991. 

Are there on-line monitors installed, for example, for the measurement of biofilm, scale, or corrosion Do they work What do they tell you What value is placed on this equipment by the operators Could this equipment be used to provide independent information in any subsequent trial ... 

Practically all of the deposit/fouling monitors discussed so far are suitable for some degree of measurement or evaluation of biomass/biofilm activity. There are also other devices available, for example, a head-loss monitor. This device is simply a 6-ft-long stainless steel tube, through which cooling... 

The major purpose of monitoring microbes is to identify the generation of biofilms and to find the locations of biofilms, if any. The purpose of sanitization is to kill and destroy the biofilm after detecting the location of the biofilms. The planktonic population, whose number of micro-organisms in water is monitored, should be understood and utilized to indicate biofilms in the system. The number of microbes in water is an indicator of system contamination levels and is the basis for the system alert levels. 

Anion detection at microelectrodes has not been studied widely. Amongst the first was the work of de Beer et al. [ 111 ] who manufactured a nitrite sensor with a tip just a few microns in diameter, which could detect nitrite ions down to 1 pM. This proved to be suitable for profiling the concentrations of nitrite anion within biofilms less than 1-mm thick inside water treatment plants. Other workers have found that use of an interdigitated microelectrode array [ 112] allows measurement of iodide via monitoring of its redox peak down to sub-micromole levels, making it a suitable technique for analysing mineral water. Carbon nanotubes coated onto Pt microdiscs have been utilised to make a nitrite sensor [113,114] with detection levels of 0.1 pM. Sulphide has also been detected at nickel microdiscs (50 pm diameter) [115]. 

AW devices have also been used in solution to measure the attachment w binding of various biomaterials. For example, TSM devices have been used to measure attachment of cells to the surface of the TSM [189-191]. As might be expected, the ceils were found to behave viscoelastically [189]. In addition, the removal of cells by a virus infection has also been monitored [190]. By improving stability to enable long-term monitoring, the slow attachment and growth of biofilms was monitored in one study [192]. 

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