Interfacial phenomena governing adhesion of chlorella to glass surfaces

Abstract

SummaryInterfacial phenomena are direct,ly involved in the adhesion of a stJrain of Chlorella, a unicellular alga, to glass surfaces in simple ionic solutions. The principal mechanisms governing the adhesion appear to be electrostatic interaction between electrical dortble layers arid various specific surface interactions resulting from surface heterogeneity and ion adsorption. Under most conditions the algal cells and glass surfaces have negat,ive zeta potentials, and adhesion to gl will not occur; but if, for example, FeC13 is added to an algal-glass system immersed in 0.05M NaC1, the algal and glass surfaces will possess very different zeta potentials, and adhesion will be strongest Iinder those conditioiis which produce the great'est difference in zeta poentials. Prior pretreatment and usage of glass apparatus greatly affect the glass zeta potentials and the adhesion of algal cells to glass. Ail apparatus for measuring a relative set of numbers representing the force of adhesion of algal cells is described.

The significance of microbial film in fermenters

“…In other circumstances, the majority of the algae was removed by an average liquid velocity as low as 1.6 x 1 0 4m s-1. Hence, while fluid forces alone will not control microbial film, the evidence suggests that an appropriate selection or treatment of surface, control of ionic strength of the environment and a satisfactory fluid (Nordin et aL, 1967). References on curves relate to Table 6 velocity might result in a situation in which microorganisms will, or will not, adhere to the surface.…”

“…Such charges may be influenced by the conditions prevailing in the environment, for example, pH, electrolyte concentration and properties of the surface. These charges can set up considerable adhesive forces, as indicated by the results of Nordin et al (1967) shown in Fig. 5 where, given appropriate conditions, the Chlorella was not washed off the glass surface when the average liquid velocity through the test cell exceeded 3 m s-1.…”

“…3 and Table 6. (Nordin et al, 1967) The Significance of Microbial Film in Fermenters Table 6. (Nordin et al, 1967) Ferric chloride was used as the electrolyte since ferric iron is necessary for the growth of this organism.…”

“…(Nordin et al, 1967) The Significance of Microbial Film in Fermenters Table 6. (Nordin et al, 1967) Ferric chloride was used as the electrolyte since ferric iron is necessary for the growth of this organism. When the charges were opposite, adhesion of the algae to the glass surface was very strong, but could still be considerable when charges were of the same sign, provided that there was a sufficient difference in zeta potential.…”

“…While the above sequence of events may offer an explanation for the formation of film on new surfaces in dilute solutions, microbial film may develop in conditions where there is no substrate limitation. Nordin et al (1967) investigated the adhesion of Chlorella to glass and measured the charges on the algal and glass surfaces. Electrolytes were used to change the charges and some results are given in Fig.…”