| dc.description.abstract | Activated sludge process (ASP) is the most commonly used biological wastewater
treatment system. Mathematical modelling of this process is important for improving its
treatment efficiency and thus the quality of the effluent released into the receiving water
body. This is because the models can help the operator to predict the performance of the
plant in order to take cost-effective and timely remedial actions that would ensure
consistent treatment efficiency and meeting discharge consents. However, due to the
highly complex and non-linear characteristics of this biological system, traditional
mathematical modelling of this treatment process has remained a challenge.
This thesis presents the applications of Artificial Intelligence (AI) techniques for
modelling the ASP. These include the Kohonen Self Organising Map (KSOM),
backpropagation artificial neural networks (BPANN), and adaptive network based fuzzy
inference system (ANFIS). A comparison between these techniques has been made and
the possibility of the hybrids between them was also investigated and tested.
The study demonstrated that AI techniques offer viable, flexible and effective modelling
methodology alternative for the activated sludge system. The KSOM was found to be
an attractive tool for data preparation because it can easily accommodate missing data
and outliers and because of its power in extracting salient features from raw data. As a
consequence of the latter, the KSOM offers an excellent tool for the visualisation of
high dimensional data. In addition, the KSOM was used to develop a software sensor to
predict biological oxygen demand. This soft-sensor represents a significant advance in
real-time BOD operational control by offering a very fast estimation of this important
wastewater parameter when compared to the traditional 5-days bio-essay BOD test
procedure. Furthermore, hybrids of KSOM-ANN and KSOM-ANFIS were shown to
result much more improved model performance than using the respective modelling
paradigms on their own. | en_US |
