Multi-criteria decision-making approach for selecting an alternative wastewater treatment plant site in urban areas of Laghouat (North-Central Algeria)

Environmental projects need decision-making that integrates environmental, socio-political, and economic factors. Finding a suitable location for a wastewater treatment plant (WWTP) can be a complex and challenging task for the government department, as it requires consideration of numerous geographic factors and their interactions. Located in North-Central Algeria, the city of Laghouat is vulnerable to natural hazards such as unpredictable floods of M’zi wadi that pose a threat to life and property in the surrounding urban and rural areas, as well as to the current WWTP. It is worth mentioning that prior studies related to WWTP concerns and possible solutions at the local or regional level have not been carried out. The purpose of the work reported in this paper was to select an alternative WWTP site in the urban areas of Laghouat City by using the analytic hierarchy process (AHP) and geographic information systems (GIS). Various alternative sites for a WWTP are presented and evaluated; the results of the analysis reveal that 2.12%, 68.25%, 29.36%, and 0.27% of the total area are of high, moderate, low, and very low suitability, respectively, for siting a WWTP, respectively. The southeast part of the study area, which has a low elevation and flat gradients, has the most appropriate candidate sites. Three possible sites were identified: site A is the most advantageous; it would be a very good site for maximizing the WWTP’s performance and effectiveness, and there is the possibility of using treated wastewater for nearby agriculture. The final suitability map can assist local government agencies and departments in making sustainable decisions in the planning phases of engineering projects.