Citation: Anti´ c, S.; Benka, P.; Blagojevi´ c, B.; Santraˇ c, N.; Salvai, A.; Staji´ c, M.; Zemunac, R.; Bezdan, J. Defining Optimal Location of Constructed Wetlands in Vojvodina, Serbia. Hydrology 2023, 10, 192. https://doi.org/10.3390/ hydrology10100192 Academic Editor: Ioannis Panagopoulos Received: 28 July 2023 Revised: 7 September 2023 Accepted: 24 September 2023 Published: 27 September 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). hydrology Article Defining Optimal Location of Constructed Wetlands in Vojvodina, Serbia Sanja Anti´ c* , Pavel Benka , Boško Blagojevi´ c , Nikola Santraˇ c , Andrea Salvai , Milica Staji´ c , Radoš Zemunac and Jovana Bezdan Department of Water Management, Faculty of Agriculture, University of Novi Sad, Trg D. Obradovica 8, 21000 Novi Sad, Serbia; pavel.benka@polj.uns.ac.rs (P.B.); bosko.blagojevic@polj.edu.rs (B.B.); nikola.santrac@polj.uns.ac.rs (N.S.); andrea.salvai@polj.uns.ac.rs (A.S.); milica.stajic@polj.uns.ac.rs (M.S.); zemunac.rados@polj.uns.ac.rs (R.Z.); jovana.bezdan@polj.edu.rs (J.B.) * Correspondence: sanja.antic@polj.uns.ac.rs Abstract: With the continuous trend of urbanization, increase in industrial capacities, and expansion of agricultural areas, there is also a rise in the amount of wastewater. One of the effective and economical solutions for wastewater treatment has proven to be Constructed Wetlands (CWs). Defining the locations where CWs can be built is not an easy task and there are several criteria that need to be considered. The Geographical Information Systems (GIS) and Multi-Criteria Decision Analysis—Analytic Hierarchy Process (AHP) are combined to select CW locations. AHP is one of the most commonly used methods in many environmental decision making problems, involving various conflicting criteria. In this case, conflicts arise between the evaluation of criteria that influence the selection of CW locations. The evaluation of selected criteria and sub-criteria resulted in a suitability map indicating that the first class represents 44%, the second class 37%, and the third class 16% of the total area. The fourth and fifth classes represent 3% of the total area. The criteria with the highest significance are land use, floodplains and distance of the location from populated places. This study has important implications for sustainable wastewater management in Serbia and provides guidelines for selecting locations for CWs. Keywords: wastewater treatment; constructed wetland; geographical information system; analytic hierarchy process 1. Introduction Anthropogenic and industrial activities are negatively affecting the quality of water bodies, leading to the gradual loss of their ecological value [1,2]. Therefore, the preven- tion of pollution and effective treatment of wastewater is a crucial issue that must be addressed. Polluted water is often discharged into the influent without prior treatment, which represents a direct cause of environmental degradation to surface and groundwa- ter, which affects various economic sectors, water management, as well as agriculture. The study region of Vojvodina (Serbia) has a high potential for Constructed Wetlands (CWs) because of the predominance of numerous decentralized rural settlements. The implementation of CWs in the area can contribute to addressing significant water and agricultural management challenges, as well as improve public health and environmental conditions. Considering that water is necessary for successful agricultural production, it is important to prevent contamination and ensure that the surface water used for irrigation is of appropriate quality [3–5]. Discharging untreated wastewater is a direct contributor to groundwater pollution in sources of water that supply for settlements, which can have detrimental effects on human health. In Serbia, the majority of wastewater is not treated. According to a report from the Serbian Environmental Protection Agency [6], it was found that the percentage of untreated wastewater in relation to the total volume of discharged wastewater for 2019 amounts to Hydrology 2023, 10, 192. https://doi.org/10.3390/hydrology10100192 https://www.mdpi.com/journal/hydrology