A KNOWLEDGE-BASED DECISION SUPPORT SYSTEM FOR SELECTING SMALL-SCALE WASTEWATER TREATMENT PROCESSES

A PC-based decision support system was developed for selecting the most appropriate small-scale wastewater treatment plant process for a given set of conditions (e.g., population and available budget for facility construction and operation and maintenance (O&M)). The system consists of: (i) a numerical database for considering treatment performance and costs, (ii) a non-numerical database (knowledge-base) for considering intangible, empirical information (e.g., O&M difficulty), (iii) an analysis module for determining effluent water qualities and costs according to the basic user-input data of an objective site, and (iv) a dialog module for controlling user input and the subsequent system output. The system provides a display listing the effluent water qualities (e.g., BOD, total nitrogen, and total phosphorus), construction and O&M costs, and a ranking score of O&M difficulty and other non-numerical parameters of each treatment processes. The user is able to sort the resultant list according to parameter values or ranking score, and can prioritize several treatment processes using the analytic hierarchy process (AHP) method. In addition, the system is capable of evaluating integrated wastewater treatment processes which combine natural purification processes such as streams or wetlands.