Viscosity bacteria effects

A loss in viscosity occurs when enzymes, organic catalysts manufactured by bacteria and/or fungi, start to destroy the thickener. These enzymes are capable of triggering reactions quickly and for indefinite periods. One enzyme molecule can effectively change millions of raw material molecules to undesirable end products. The result can be a paint or coating that loses its elastic and elonga-tional properties. 

A variety of factors affect the horizontal and vertical migration of PAHs, including contaminant volume and viscosity, temperature, land contour, plant cover, and soil composition (Morgan Watkinson, 1989)- Vertical movement occurs as a multiphase flow that will be controlled by soil chemistry and structure, pore size, and water content. For example, non-reactive small molecules (i.e., not PAHs) penetrate very rapidly through dry soils and migration is faster in clays than in loams due to the increased porosity of the clays. Once intercalated, however, sorbed PAHs are essentially immobilized. Mobility of oily hydrophobic substances can potentially be enhanced by the biosurfactant-production capability of bacteria (Zajic et al., 1974) but clear demonstrations of this effect are rare. This is discussed below in more detail (see Section 5 5). 

Colloids are either hydrophilic (water-loving) or hydrophobic (water-hating). Hydrophilic colloids (e.g., proteins, humic substances, bacteria, viruses, as well as iron and aluminum hydrated colloids) tend to hydrate and thereby swell. This increases the viscosity of the system and favors the stability of the colloid by reducing the interparticle interactions and its tendency to settle. These colloids are stabilized more by their affinity for the solvent than by the equalizing of surface charges. Hydrophilic colloids tend to surround the hydrophobic colloids in what is known as the protective-colloid effect, which makes them both more stable. 

There are four bacteria in reservoirs, and their concentrations are in the order of TGB-0 > TGB-A > HOB > SRB. Their effect on polymer viscosity loss is shown in Fignre 5.34. Their concentrations were 2% with 10 bacteria in 1 mL liquid (these concentrations are much higher than typical values in reservoirs, though). The polymer concentration was 1000 mg/L. 

FIGURE 5.34 The effect of bacteria on polymer viscosity. Source Data from Niu et al. (2006). 

The injection scheme was optimized by simnlation using the modified UTCHEM 6.0. The final selected formula was 2% NaC03 + 1000 mg/L 1175A. The simulation results showed that the performance from different injection sequences was similar for the same mass of chemicals. Operation experience shows that polymer viscosity would be reduced by about 50% from the surface to the wellbore by mechanical shear loss, iron effect, and bacteria degradation. Therefore, in the performance prediction, the viscosity was assumed to be 50% of the measured viscosity in the laboratory. Economic analysis was also included in the optimization process to select the best injection scheme. 

The main causes of viscosity loss of cellulose ethers are of microbial (b u teria, fungi and enzyme) and chemical (redox process) natures. Biocides are used to kill bacteria and fVingi but they are usually not effective against enzymes. The enzymatic liquefaction is known to be the strongest process. Studies have been made on different cellulosic thickeners with bacteria, fungi and commercial cellulase enzyme juid the overall conclusion was that cellulase is the most significant cause of viscosity loss. ... 

In this research, cetyl trimethyl ammonium bromide (CTAB), as an arrtimicrobial ent is applied on polyester, polypropylene and viscose non-woven fabrics alone and in combination with a Fluorochemical (FC 1112). The antimicrobial, water and blood repellency of the treated samples were investigated. To reveal the antimicrobial properties of the treated samples, the zone of inhibition and reduction of bacteria were measured with S. aureus, E. coli and P. aeroginosa. The results showed a good antimicrobial property on different concentration of CTAB solutions (1%, 2%, 4% and 8%). Application of CTAB with concentration of (0.5%, 1% and 2%) on polyester, polypropylene and viscose nonwoven fabrics indicated a reasonable antimicrobial effect Co-application of CTAB with fluorochemical on different samples also showed a good antimicrobial, water and blood repellency properties. 

The results of antimicrobial activities of polyester and polypropylene treated fabric with different bacteria are indicated in Tables 1-5. The inoculum was a nutrient broth culture containing 0.5x10, Ixio and 1.5 xlO /mL colony-forming units (CPU) of the bacterium. The results show that 1% and higher concentration of CTAB on both polyester and polypropylene fabrics reasonably inhibit the growth of E. coli at pH=7 and S. aureus and P. aeroginosa at pH=5.5 (pH=5.5 is the pH of body skin). This test can not be used for viscose nonwoven because of disturbing effect of adhesive used for fabric production. 

Synthetic fibers such as polypropylene and polyester are commonly used in the construction of surgical drapes and gowns as well as viscose. Antimicrobial nonwoven fabrics were prepared by directly incorporation of a qurteroary ammonim salt namely, cethyl trime yl ammonium bromide, on polyester and polypropylene and viscose nonwoven fabrics. An interesting observation is the clear zone of inhibition and excellent reduction of bacteria growth on polyester and polypropylene fabrics. It is apparent that the antimicrobial activity of CTAB is bactericidal in nature and not bacteriostatic. CTAB was effective as antibacterial agent on E.coli for three different fabrics. However CTAB was not effective on S. aureus and P. seudomonas when applied to viscose fabrics which may suggest that nature of substrate influence on the antibacterial activity of CTAB. 

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