A model for the use of urban treated wastewater in agriculture using multiple criteria decision making (MCDM) and geographic information system (GIS)

The limited water resources have forced the use of unconventional water such as urban wastewater in agriculture. However, using these water resources requires the consideration of their impact on water, soil, human and environment. Inthis study,the suitability of using urban treated wastewater as irrigation water has been investigated using geographic information system (GIS) and multi criteria decision making (MCDM).To do this, the decision-making criteria were extracted after a literature review. Irrigation water availability, techno-economic distance from the wastewater treatment plant, and suitability of farmlands for crop cultivation were considered as techno-economic sub-criteria while the quality of irrigation water, soil, and crop as well as aquifer vulnerability were considered as environmental sub-criteria in the decision structure. The data of two wastewater treatment plants, i.e., Bandar Gaz and Kordkoy located in west of Golestan province(Iran) were used to implement the model for 10 common crops. Topography, land use, soil depth, and technical allowable distance were considered as limiting factors in urban wastewater use in the area. After the preparation of the base maps, appropriate areas were determined for model implementation. The maps associated with the criteria were prepared in the GIS software environment and then classified according to the available standards. Analytic hierarchy process (AHP) was used to calculate the weight of the criteria. The results of the sensitivity analysis showed the high sensitivity of aquifer vulnerability and microbial contamination. The comparison of the suitability of cultivation using the treated wastewater revealed the better performance of Bandar Gaz plant in some effective criteria such as aquifer vulnerability, nitrate contamination burden, and suitability for crop cultivation.