Application of sodium ferrate produced from industrial wastes for TOC removal of surface water H. Momtazpour, S. Jorfi, T. Tabatabaie and A. A. Pazira ABSTRACT This study aimed to investigate the effect of sodium ferrate synthesized from industrial effluents (SF-W) and that of synthetized from analytical grade chemicals (SF-O) on total organic carbon (TOC) removal from surface water. Response surface methodology (RSM) was used to optimize the operating variables such as pH, dosing rate, rapid mixing time, and gentle mixing speed on TOC removal. A TOC removal of 89.805% and 79.79% was observed for SF-O and SF-W, respectively. Ferrate as SF-O and SF-W demonstrated 26.67% and 8.51% more TOC removal at a lower dosage compared to conventional chemicals such as chlorine, ozone, poly aluminum chloride (PAC) and polyelectrolyte. The optimum conditions of the independent variables including sodium ferrate (SF-O and SF-W), pH, rapid mixing time and gentle mixing speed were found to be 1.54 mg/L and 2.68 mg/L, 8.5, 30 s at 120 rpm for coagulation followed by 20 min of gentle mixing. Economic analysis showed that the application of SF instead of conventional chemicals provides a significant reduction in operational costs by about 68%, mainly because of the reduction of chemicals and energy consumption. H. Momtazpour Department of Environmental Engineering, Isfahan Regional Water Organization, Isfahan, Iran S. Jorfi (corresponding author) Department of Environmental Engineering, Faculty of Environmental Health, Ahvaz Jundishapur University of medical Sciences, Ahwaz, Iran and Environmental Technologies Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran E-mail: sahand369@yahoo.com T. Tabatabaie A. A. Pazira Department of Environmental Engineering, Bushehr Branch, Islamic Azad University, Bushehr, Iran Key words | industrial waste, response surface methodology, sodium ferrate, TOC removal, water treatment ABBREVIATIONS SF-O Sodium ferrate produce from original matter SF-W Sodium ferrate produce from industrial matter SF Sodium ferrate TOC Total organic carbon RSM-D- Optimal Response surface methodology determination optimization ANOVA Analysis of variance PAC Poly aluminum chloride INTRODUCTION Natural waters contain a wide variety of organics which may be harmful to the environment and public health. Total organic carbon (TOC) is a common index of organic contaminants in water and wastewater. All water samples, even pure ones, contain some carbon materials introduced into the water from the water source, discharge of waste- waters or during purification and treatment (Ahmadi et al. ). Removal of organics is one of the main goals of water treatment practices, since these organics may be com- posed of toxic substances, recalcitrant materials, pathogens etc. TOC removal is particularly important because certain disinfectant by-products (DBPs) such as haloacetic acids (HAAs) and trihalomethanes (THMs) can be produced during pre-chlorination. Chemical reagents are dosed into the water stream to increase the effectiveness of the settling or filtration process (Zainal-Abideen et al. ). The cost of achieving the desired level of water quality depends primar- ily on the cost and the availability of the chemical reagents (Sharma ). These coagulants are often expensive and in many developing countries they have to be imported. Moreover, the high sensitivity of inorganic coagulants to the pH and the possibility of secondary contamination of drinking water with traces of coagulants or residual iron and aluminum ions are the main challenges of coagu- lation-flocculation in water treatment processes ( Jiang et al. ). To overcome these drawbacks, novel, low-cost and multiple role (coagulation, disinfection and oxidation) 1263 © IWA Publishing 2019 Water Science & Technology | 79.7 | 2019 doi: 10.2166/wst.2019.127 Downloaded from http://iwaponline.com/wst/article-pdf/79/7/1263/618379/wst079071263.pdf by guest on 17 September 2023