Fouling biofouling

Fig. 10.2 Various monitoring devices (1 to r) corrosion/fouling/ biofouling mesh coupons, LPRM monitor, corrosion rack, deposit monitor, membrane filter on poured plate, and dip-slide... 

The processes of interest are NFand RO where the membranes are either nanoporous or essentially nonporous. In these processes the fouling is a surface layer, the effects of which maybe exacerbated by the high retention of solutes by the membrane. Operation is with crossflow and in industry fixed flux is commonly used. This section considers particulate fouling, biofouling and scale formation and then discusses the implications of cake enhanced concentration polarization on fouling outcomes. 

Sulfate scale Organic Fouling Biofouling Silica... 

Open the feed side of a pressure vessel and inspect for fouling. Biofouling will feel slippery and may also have an odor. 

Dickinson et al. also used microelectrodes to measure dissolved oxygen (DO), H2O2, and local within biofouling deposits on stainless steel surfaces exposed to river water to further resolve the interfacial chemistry that resulted in ennoblement. Data were then compared with those from similar measurements as close as possible to the environment of a non-fouled substratum. 

Fig. 5.1.10 (a) MR measured propagators and (b) corresponding calculated RTDs for flow in a model packed bed reactor composed of 241 -pm monodisperse beads in a 5-mm id circular column for a fixed observation time of 300 ms and as a function of biofilm fouling. As the porous media becomes biofouled, a high veloc-... 

Springer-Verlag, Berlin, Heidleberg, pp 141-170 Callow ME, Callow JA (1998) Enhanced adhesion and chemoattraction of zoospores of the fouling alga Enteromorpha to some foul-release silicone elastomers. Biofouling 13 157-172... 

Hoffman LR (1960) Chemotaxis of Oedogonium sperms. Southwestern Nat 5 111-116 Holmstrom C, James S, Egan S, Kjelleberg S (1996) Inhibition of common fouling organisms by marine bacterial isolates with special reference to the role of pigmented bacteria. Biofouling 10 251-259... 

Godwin, L. S., (2003), Hull fouling of maritime vessels as a pathway for marine species invasions to the Hawaiian Islans Biofouling, Vol. 19(supplement), 37-43. 

Holm E.R., Schultz M.P., Haslbeck E.G., Talbott W.J., Field A.J. Evaluation of hydrodynamic drag on experimental fouling-release surfaces, using rotating disks. Biofouling 20(4-5) (2004) 219-226... 

Fouling by salts, oils, corrosion prods, air-blown debris biofouling... 

Flow-Based Systems Needle-type sensors with a fluid flowing over the sensor tip seem to resist biofouling and extend sensor lifetime.31 There are numerous methods that have been investigated for flow-based sensors, such as microperfusion systems,75 microdialysis,76 77 and ultrafiltration.78 Reduced fouling was found with an open microflow system where slow flow of protein-free fluid over the sensor surface at the implant site is effected.73 Different from the other flow-based sensors, the open microflow is controlled by the subcutaneous tissue hydrostatic pressure and does not require a pump. 

Figure 11.1 Top Modeled response of a flux-based glucose sensor subject to a moderate biofouling rate. The sensor signal decreases immediately and is rendered useless after 3.7 days. Bottom Modeled response of an optical glucose sensor subjected to the same fouling rate. The measured signal is not affected until a period of 76 days. Adapted with permission from Ref. 17.

FIGURE 3.4 Biofouling reduces the exchange kinetics of PRCs (deuterated acenaphthene and fluorene) between the nonpolar Chemcatcher sampler (fitted with either fouled or unfouled LDPE membranes) and water. The experiment was performed in a laboratory flow-through calibration system at a water temperature of 11°C with simulated water turbulence of 40 rpm. MD(t)/MD(0) is the fraction of the PRC remaining in the sampler during exposure. 

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