Nonlinear Dynamic Features And Fractal Structure On Biofilms

Microbial biofilm is a kind of universal biological community, which occurs in a wide variety of aqueous environments, food industry and pipelines, such as pipelines for water supply, drainage, water circulation and cooling water. Microbial biofilms is encountered in various applications, including traditional industrial processes, such as various biochemical operations, wastewater treatment. Biofilms form a very complex biological community as an open, multi-level, multi-scale, nonlinear system far from equilibrium in which many species of microorganisms exist and a variety of complex physical, chemical and biological reactions occur.Fundamental theoretical depiction is still lacked on biofilm wastewater treatment systems up to today. A mathematical model on biofilm wastewater treatment systems, taking account of suspended microorganisms and some factors influencing biofilm formation and stabilization, is developed in the paper. By theoretical and numerical analyses, the factors influencing biofilm formation and stabilization, such as the dilution rate, influent organic concentration, detachment and initial inoculum's concentration etc, are discussed. Quantitative investigations are carried out and suggestions on industrial applications are then proposed. The paper not only plays an important role on understanding the physical mechanisms of biofilm dynamics, but also has far-reaching implications for industrial practices.Macroscopic characteristic is closely related to the microscopic mechanisms. Microscopic dynamics may be described by maximum flux principle (MFP): an open system far from equilibrium always seeks an optimization process so that the obtained flux from outside is maximal under given prices or constrains. On the basis of MFP, this paper proposes a new non-equilibrium statistical mechanics framework to analyze the interactions among cells and their environment, and the self-organizing formation process of biofilm is elaborated. The paper tries to make a renewed attempt to illustrate the emergence of complexity of the biofilm community and reveal the mechanism of producing macroscopic microbial biofilm pattern from microscopic microbial cells interaction. These studies may not only provide a more reasonable physical description on microbial biofilms, but also find important engineering instructions. Biofilms with a conspicuous hierarchical and fractal structure has been explained by MFP. The influences of component of generalied...