University of Guilan Caspian Journal of Environmental Sciences 1735-3033 2024 02 22 Recovery of FeCl3 coagulant by acid digestion and Nafion 117 membrane method and its environmental and biological evaluation 1 7 7597 10.22124/cjes.2024.7597 EN Farhad Panahi Department of Environmental Sciences and Engineering, Lahijan Branch, Islamic Azad University, Lahijan, Iran Hasan Karimzadegan Department of Environmental Sciences and Engineering, Lahijan Branch, Islamic Azad University, Lahijan, Iran Fatemeh Shariati Feizabadi Department of Environmental Sciences and Engineering, Lahijan Branch, Islamic Azad University, Lahijan, Iran Abdolkarim Keshavarz Department of Environmental Sciences and Engineering, Lahijan Branch, Islamic Azad University, Lahijan, Iran Journal Article 2024 02 22 Coagulant materials are usually expensive and the purchase, transportation, and maintenance costs are high for all water treatment plants. The disposal of sludge resulting from used coagulants also requires knowledge-based management, and it is necessary to foresee scientific and economic points of view for the disposal of sludge resulting from coagulants in the environment. The present study aimed to design cost-effective and simple Ferrum-based coagulants. So, Fe³⁺ was recovered through acid digestion and the Nafion 117 membrane, then these methods efficiency was compared together. The present study showed that the average recovery rates (%) of Fe³⁺ by acid digestion and Nafion 117 membrane were 73% and 71.5% after 30 and 25 min, respectively. Also, the ratio of return sludge to sulfuric acid was 40:60 during the acid digestion method. According to the results, the Nafion 117 membrane in addition to a significant effect in reducing the concentration of FeCl₃ in wastewater did not release sulfuric acid, meaning that reducing the disposal of chemical sludge by Nafion 117 has not environmental negative effects, and can prevent the biological and physical degradation of farms. https://cjes.guilan.ac.ir/article_7597_7987c7be3788b397eddde1131fbc4390.pdf