|
The paper presents the development of an expert system to assist in the operation of wastewater treatment plant. The knowledge-based system consists of a rule-based expert system for the diagnosis of activated sludge process and subsequent identification of remedial control actions. The activated sludge is a commonly used method for treating wastewater. Due to the biological nature of the process it is characterized by a poorly understood basic biological behavior mechanism, lack of reliable instrument and by control goals that are not always clearly stated. It is generally recognized that an expert system can cope with many of the common problems related to the operation and control of the activated sludge process. In this work, an expert system is developed which supervises the control system of the whole treatment plant. The knowledge acquisition to develop this expert system involved an exhaustive literature review on wastewater treatment plant operation and interviews with experienced plant operators. The development tool for this system is Kappa-PC.
Wastewater is a combination of the water-carried wastes produced from domestic, commercial and industrial sources. It has a very complex composition, containing many forms of polluted matter, dissolved impurities, and a heterogeneous dispersion of organic and inorganic solids, both colloidal and suspended. If wastewater is not effectively treated, several problems can occur: pollutants will be returned to the environment; decomposition of organic components evolves malodorous gases; diseases may be spread by microorganisms present in the water or by poisoning due to toxic compounds; and the organic nutrients in the wastewater may stimulate the growth of aquatic plants (Serra et al., 1994). For these reasons, the immediate and nuisance-free removal of wastewater from its sources of generation, followed by treatment, reuse, or dispersal into the environment is necessary to protect public health and the environment (Metcalf and Eddy, 2004).
During the last decade, the research in wastewater treatment has been concentrated mainly on the operation rather than the design and construction of the treatment plants. This is due to the fact that the management and operation of the plants is the key step for the efficiency of water pollution control. The complexity of the process used in wastewater treatment, the inadequate and unreliable on-line instruments, the absence of appropriate performance specifications on which to base control, the limited flexibility in plant design, the lack of accurate process models and the excess influent variability have showed that the existing control technology has not been applied effectively (Paraskevas et al., 1999). |
