Providing Water Quality Index for Water use in Agriculture: A Case Study

Background: Most countries face water scarcity, population growth, climate change, uneven water distribution, excessive water use, and biological, agricultural, and industrial water pollution. Using wastewater and brackish waterways for cultivation reduces pollution. Polluted water impacts human biology. Thus, they must be adequately studied before irrigating crops. Methods: This study used the analytical hierarchy process (AHP) to assess the quality of nonconventional agricultural waters from the Karaj and Anbaj wastewater treatment plants in Iran. Water quality was evaluated based on 7 primary criteria and 52 sub-criteria. The Canadian Water Quality Index (CWQI) and the proposed model were developed from the measured parameters of the effluent from both the Anbaj and Karaj treatment plants. The data were analyzed using the Expert Choice software. Results: In this study, chloride, fecal coliforms, and intestinal parasite eggs received the highest scores, while arsenic (As) and molybdenum (Mo) were assigned the lowest scores. The findings indicated that the effluent from the Anbaj wastewater treatment plant requires extensive treatment before being suitable for agricultural use. In contrast, the effluent from the Karaj wastewater treatment plant was of moderate quality and requires minimal treatment. This study recommends applying the proposed model to evaluate wastewater quality for agricultural purposes. Conclusion: Researches of soil and wastewater interactions suggests that crops irrigated with wastewater may pose risks to both ecosystems and human health due to physical, chemical, and microbiological factors. These impacts can compromise soil fertility and productivity. Therefore, the use of wastewater in agricultural practices should be implemented with appropriate safeguards.