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

A PC-based decision support system was developed for selecting the mos t appropriate small-scale wastewater treatment plant process for a giv en set of conditions (e.g., population and available budget for facili ty construction and operation and maintenance (O&M)). The system consi sts of: (i) a numerical database for considering treatment performance and costs, (ii) a non-numerical database (knowledge-base) for conside ring intangible, empirical information (e.g., O&M difficulty), (iii) a n analysis module for determining effluent water qualities and costs a ccording to the basic user-input data of an objective site, and (iv) a dialog module for controlling user input and the subsequent system ou tput. The system provides a display listing the effluent water qualiti es (e.g., BOD, total nitrogen, and total phosphorous), construction an d O&M costs, and an ranking score of O&M difficulty and other non-nume rical parameters of each treatment processes. The user is able to sort the resultant list according to parameter values or ranking score, an d can prioritize several treatment processes using the analytic hierar chy process (AHP) method. In addition, the system is capable of evalua ting integrated wastewater treatment processes which combine natural p urification processes such as streams or wetlands.