Knowledge-based expert system applications in waste treatment operation and control

Abstract

Experience has shown that operation of wastewater treatment processes can be difficult. In some plants, poor performance, high costs, and damage to the environment have resulted from operational problems. Progress in control engineering, computer technology, and process sensors has enabled development of computer-based systems for automatic control and operations support in wastewater engineering. In the area of automatic control, important advances have been made; however, because of the unique character of wastewater treatment, techniques other than a straightforward application of control theory are needed to achieve effective control. Preparing computer-based tools to aid in operation is a modelling task, with the primary objective being to represent knowledge about a process and its operation. The traditional approach is to use mathematical methods for this purpose. More recently, tools and techniques from applied artificial intelligence have been used to prepare systems that encapsulate knowledge of diagnostic and control decision tasks. These knowledge-based (expert) systems (KBES) show promise as aids in support of such tasks. Several KBES development projects have been reported with varying degrees of success. There is a high level of interest in KBES, but few full-scale systems have been reported. Most of the documented problems concern initial elicitation/capture of knowledge and final verification/validation of the KBES. Recently, improved KBES have been reported including object-oriented systems, systems using deep knowledge representations for qualitative reasoning, and integrated systems that make use of numeric and symbolic processing.