Surface Tension Model

DIY 3D Solar Panels

Do It Yourself Solar Energy

Get Instant Access

According to the thermodynamic theory, microbial granulation is a creation process for a new granule-liquid interface by disrupting preexisting individual bacteria-liquid interface, and a molecular contact between the two adhering bacterial surfaces is involved. The free energy of adhesion

(AGadh) can be expressed as follows (Rouxhet and Mozes, 1990): AGadh = 20^ - rl1/2)(rl1/2 - r^2)

where, rc is the surface free energy of bacteria, rl is the surface free energy of liquid, and rs is the surface free energy of inert particle.

This equation shows that if the surface free energy of bacteria is lower that that of the liquid, the free energy of aggregation decreases and aggregation is favored with decreasing surface energy of the inert carrier. The opposite trend would occur if the surface energy of bacteria is higher than that of the liquid. In fact, the above thermodynamic equation is a theoretical basis of the surface tension model. It was found in a UASB reactor that aggregation of hydrophilic cells was enhanced at low liquid surface tension, while the opposite was true for hydrophobic cells (Thaveesri et al., 1995). Depending on the liquid surface tension (y) in the UASB reactor, bacteria may grow in rather loose associations, in multilayered granules (y < 50mN/m), or in mixed conglomerates (y > 56mN/m) (Thaveesri et al., 1995; Grootaerd et al., 1997).

Was this article helpful?

0 0
Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook


Post a comment