Environmental Engineering Reference
In-Depth Information
function of the concentration of the bacteria at the interface and the rate constants
for growth, desorption and adsorption. The models have several assumptions and
the limitation of the models can be minimised by experimental data.
Fedorovich and co-workers [56] presented a mathematical model on the kinetics of
bacterial adsorption on polymeric materials that are hydrophobic. This model has
two components, the irst characterises the interactions based on the hydrophobic
properties of the bacteria and polymers and the second component describes all
the other types of interactions. This model could calculate the amount of bacteria
attached on the surface in a certain period of time. The experimental validation of
the model showed that the accuracy of prediction of a number of bacteria adsorbed
on the surface decreased with increasing surface hydrophobicity.
Although the use of mathematical models may be insightful, the interpretation of
quantitative data derived from them must be done with caution because of several
assumptions required to develop the model and lack of controlled data.
6.1.3.2 Modelling of Biodegradation
Modelling the biodegradation of polymers has gained importance for evaluating and
predicting the impact of the process on the material. Understanding the environmental
conditions and products formed because of degradation is needed to predict the shelf
life of materials. However, there has been a very limited amount published on the
mathematical modelling of biodegradation. Kinetic and mechanistic models have
been developed to describe biodegradation by microbes and enzymes [57]. But most
of the mathematical equations developed are for speciic reactions, and are usually
suitable only for speciic polymer systems.
Kinetic models have been applied to study the degradation of polymers by enzymes,
assuming that the degradation is irst or second order reactions [58]. One of the
complications in developing a kinetic model for polymeric systems is retaining a
convenient model size. As synthetic polymers degrade into a number of products
of varying length and composition following each is computationally challenging
using the current hardware systems [58]. The mathematical model proposed by
Duguay and co-workers [59] describes the
in vitro
enzymic degradation of biomedical
polyurethanes using a single enzyme.
A phenomenological diffusion-reaction model to predict the biodegradation of
biodegradable polymers was developed by Wang and co-workers [60]. The results
from this model were represented in the form of biodegradation maps. The maps
could show the conditions where the biodegradation was controlled by autocatalysis
