Improving the performance of wastewater treatment plants: An expert systems approac

Wastewater treatment plants in the United States have not been performing as well as expected, and this performance problem could be remedied by improving the ability of plant operators to respond to operating problems. This research developed a prototype expert system, called SLUDGECADET, that can assist a novice operator in diagnosing and recommending remedial action for a limited number of operating problems. SLUDGECADET was designed to be transferable among plants that have trickling filters for secondary treatment and anaerobic digesters for sludge treatment. This research made an effort to characterize the expertise used in diagnosing operating problems at wastewater treatment plants.;The first task in this research was identifying and selecting experts for prototype development. Experts from a consulting firm, ES2 Environmental Services, Berkeley, California, were selected to contribute information for the transferable portions of the prototype. The staff of the Fort Lewis Wastewater Treatment Facility, Fort Lewis, Washington, contributed their understanding of how to diagnose failures at a specific site.;Knowledge acquisition is the process by which the experts' expertise is elicited for use in creating an expert system. The experts' interests and advice shaped the methods used during the knowledge acquisition process and established some results characterizing expertise. The diagnostic strategies elicited during knowledge acquisition were used to develop a conceptual model of the experts' problem solving methods. The conceptual model characterized the experts' knowledge as being firmly established in wastewater treatment theory and containing strategies that are not discussed in the pertinent literature. The latter contained procedures for identifying problems caused by interactions among unit processes.;Two validation experiments tested SLUDGECADET against three standards: an internal expert, an external expert and test cases taken from actual operating problems from the Fort Lewis wastewater treatment facility. The internal expert participated in the development of the prototype; the external expert was not involved with the prototype until the testing experiments. The validation experiments reinforced the use of engineering principles and emphasized interactions among plant processes and operating problems.